LX Series Free Programmable Controllers Wizard User s Guide

Transcription

1 LX Series Free Programmable Controllers Wizard User s Guide LX-PRG5x0-1, LX-PRG4x0-1, LX-PRG300-1, LX-PRG203-1 Code No. LIT Issued June 22, 2009 Free-Programming Wizard Why Use Programming in Controls? Modular Programming Programming Language Syntax Programming Process Functional Elements of the BASIC Code Free Programming Wizard Built-in Functions Wizard Interface Main Menu File Menu Edit Menu (Code window only) Settings Menu Tools Menu Windows Menu Toolbar Refreshing Values/Data Advanced User Right-Click Menu Main Window Internal Points Module Variables Hardware Configuration Input Parameters Input Type Output Parameters LX Series Free Programmable Controllers Wizard User s Guide 1

2 Output Type Input and Output Network Variables Networks Configuring Network Variable Inputs (NVIs) Fan_in dedicated NVIs Network Variable Outputs (NVOs) Reserved Words Mathematical Operators Arithmetic Operators Comparative Operators (used only in IF statements) Logical Operators (used only in IF statements) Remarks Remarks Definition Chronological Reserved Words Chronological Reserved Words Definition Built-In Commands Definition SQRT HWOUT_OVR_VALUEx OUT_MODE_x IF Statement (Conditional Execution) Syntax and Logic Sample Codes Controllers-Proportional-Integral-Derivative (PID) Loop Definition and Logic Proportional Integral Derivative Tuning the PID Loop LX Series Free Programmable Controllers Wizard User s Guide

3 Logs Definition and Logic Configuration Format Parameters Timers Definition and Logic Optimum Starts Definition and Logic Override Definition and Sample Code First Generation (LX-VAVCx-0, LX-VVTCx-0) VAV Platform Flow and Damper Configuration 66 Reserved Internal Points Methodology Second Generation (LX-VAVCF-1) VAV Platform Flow and Damper Controller Configuration 71 Reserved Internal Points LX Series Free Programmable Controllers Wizard User s Guide 3

4 4 LX Series Free Programmable Controllers Wizard User s Guide

5 Free-Programming Wizard The Free Programming Wizard allows you to perform all programming related tasks in a controller. These tasks include setting default values to variables, defining constants, and configuring various parameters for utilities such as timers, network variables, and logs. Use the Free Programming Wizard to define and organize the tasks of LX Series Controllers. The wizard allows for effective building management. For example, you can write a program to set the allowed temperature in a room in your project, or you can write a program to set the same temperature in all rooms in a building. The information in this guide explains the functional logic that governs the use of the Wizard. This document discusses information regarding the programming language, including all commands, syntax, and utilities. Why Use Programming in Controls? The purpose of our Free Programming Wizard is to simplify the programming process while maintaining effectiveness and configurability. Control systems have become the centerpiece of building management technology. People use controllers to manage and integrate multiple systems within a building, such as heating, ventilation, and security. As a system integrator, your goal is to have a precise, easy, and cost-effective control system that allows you to set up your process according to your design parameters and equipment specifications. The best way to do this is to program the device to do your bidding. With the introduction of microprocessor-based controllers (LX Series controllers), programming is now a powerful method of system optimization. Modular Programming One of the biggest challenges all programmers face is how to structure their programs. It may be a simple task to write a program to determine a temperature setpoint in a room for example, but it is a much more complicated task to do the same in every room in a 10 story building. The complexity increases when you have to integrate multiple systems and controllers; the larger the system, the larger the program. To structure programs, the programmers wanted some formal way of constructing a program so that it can be built efficiently and reliably. Research demonstrates that constructing a program can be best done by decomposing a program into suitable small modules, which can be written and tested before being incorporated into larger modules that are constructed and tested. When you design your code in this manner, it makes your programs shorter and easier to read and troubleshoot. 5

6 Example: You have to write a program that, in addition to other things, must control the temperature in every classroom in a school. Instead of writing a program for every classroom, you write a generic program that could apply to any room. So instead of writing 10 programs for 10 classrooms, you only write one and then adjust it for each room. This generic temperature program becomes a module in your overall program. Programming Language Free Programming Wizard uses a unique and simplified version of Beginner s All-Purpose Symbolic Instruction Code (BASIC) that is custom made to suit control requirements. Through the original combination of built-in functions and an easy to use Graphical User Interface (GUI), the Free Programming Wizard offers you the very best in modular control programming. BASIC BASIC is a high-level computer language designed to make computer programming easy for beginners to learn, while at the same time still ensuring powerful programs. BASIC uses simple English words to represent programming functions; this is the main reason why BASIC is easy to learn, and its syntax is simple and intuitive. Syntax Syntax is defined as the rules governing the formation of statements in a programming language. This user guide provides all the syntax rules of the Free Programming Wizard so you write an error-free program. Also, we provide you with examples of every command in code format. In addition, the Free Programming Wizard has a built-in syntax check function that corrects your code as you type it line by line. This function makes it difficult to make mistakes, leading to shorter debugging times. 6

7 Programming Process Controls programming is a process with multiple steps starting with understanding the application requirements and the sequences of operation. When you develop your understanding, the system should be partitioned into control loops or zones that are essentially units in the overall control process. You should also establish what your inputs and outputs are for each loop, and any global inputs and outputs. Then you can start writing your program according to the syntax rules provided and using the built-in functions and programming utilities. Finally you can debug to check for errors, and compile to load your program into the controller. The following figure illustrates this entire process. Start Analyze control application requirements System Drawings and sequences of operaration Partition into control loops Determine inputs and outputs for each loop Design, write and compile program Run, debug and simulate programs Download program and associated files to controller End Figure 1: Programming Process 7

8 Functional Elements of the BASIC Code There are four function elements of the BASIC Code: Data Types (Variables, Constants, Inputs, Outputs, Input Network Variables, Output Network Variables) Mathematical Operatives (Logical, Comparative, Arithmetic) Reserved words and Built-In Commands (IF, AVERAGE, HISEL) Built-in Functions (Controllers, Timers, Optimum Starts, Logs) Free Programming Wizard Built-in Functions Five tools are available in the Free Programming Wizard to enhance its capabilities and to assist you in designing your program. The built in tools are: Controllers Logs Optimum Starts Timers Overrides 8

9 The built in functions are configured through the GUI. Use reserved words to insert the tools into the code. Figure 2 shows the main window of the Built-In Functions module. This window is accessed by clicking on Built-In Functions in the left window menu. Double-click on the individual configuration window of each Built-In Function to access it. Figure 2: Free Programming Wizard Built-in Functions Main Window Wizard Interface This section deals with the all the commands available in the menu bar and all the buttons in the toolbar of the Free Programming Wizard. Main Menu Figure 2 shows the general window of the Free Programming Wizard. Use the menu in the left window to navigate to the different parts of the wizard by clicking on the item. 9

10 Use the menu bar on the top for managing the wizard. The menus are File, Edit, Settings, Tools, Windows, and Help. Also, some graphical buttons are located directly under the menu bar. The buttons are: Save All, Print, Find, Linear Equation, Tile Horizontally, Tile Vertically, Synchronize, Reset, Error, and Help. Figure 3: Free Programming Wizard Main Window 10

11 File Menu The File menu contains functions essential for managing your programs (Figure 3). Table 1 describes the File Menu. Figure 4: File Menu Table 1: File Menu Menu Selection Save All Reload all from database Download all to device and save Upload all from device Clear workspace Import Export Description Saves all of the written code and all the configurations of the Internal Points, Built-In Functions, Hardware Configurations, and Network Variables into your Facility Explorer database. Loads the saved code and configuration settings of the database. This feature is only available in Advanced User mode. Downloads the BASIC code and configuration settings in the controller and saves it to the Facility Explorer database. This feature is only available in Advanced User mode. Uploads all the configuration settings from the controller. This feature is only available in Advanced User mode. Clears all the BASIC code and configuration settings from the Free Programmable Tool. This feature is only available in Advanced User mode. Opens a file browser on your computer and allows you to import an existing program code and configuration file (.fpc and.bsi). Opens a file browser and allows you to save your current code and configuration into a file that you can import into another controller using the Free Programming Wizard. You can export only in.fpc format. Note: You can import a.bsi format, but you cannot export a.bsi format. The.fpc format is the new file format being used by the Free Programming Wizard. This new format has many changes and improvements that enhance the performance of the controllers. To preserve backward-compatibility, we have enabled.bsi import, but it is your responsibility to remove or adjust any inconsistencies (such as obsolete commands or reserved words). 11

12 Table 1: File Menu Menu Selection Backup Restore Print Setup Print Exit Description Enables you to save a copy of the code and all configuration settings in the controller's memory for retrieval at a later date, or for use with another computer that does not have the database saved on its hard disk. This feature essentially makes the controller independent of the computer. The controller must be online and accessible through the Facility Explorer. Enables you to retrieve the backup version of the code and all configuration properties from the controller's memory. The controller must be online and accessible through the network management tool (for example, Facility Explorer) for this option to work. Microsoft Windows Operating System (OS) print setup page allows you to select which printer, paper type, and layout. Click on Print after you make your selections to start the print job. Click Cancel to close the window without registering any of the changes you made. Displays a pop-up window prompting you to select which items to print (Figure 5). Click on the box next to the item(s) you wish to print. Click OK, which opens the print dialog box. Click on Print after you make your selections to start the print job. Click Cancel to close the window without registering any of the changes you made. Closes the Free Programming Wizard. If you have made any changes to your code, the wizard asks you if you would like to save the changes; click Yes to save and No to discard the changes in the code. All changes to the Internal Points, Hardware Configuration, Network Variables, and Built-in Functions are saved automatically upon entry. Figure 5: Print Selections 12

13 Edit Menu (Code window only) The Edit menu is accessible only when in the Code Editor window. This menu deals with all text editing and searching operations within the Code Editor. To access the Code Editor window, click Code in the left-hand portion of your screen. You may access the same commands that are in the Edit menu by simply rightclicking while your cursor is in the Code Editor. Figure 6: Edit Menu Table 2: Edit Menu Menu Selection Undo Redo Cut Copy Paste Description Reverses actions in the Code Editor. You may also press Control + Z to perform this function. Reapplies an action in the Code Editor. You may also press Control + Y to perform this function. Removes a selected portion of text and holds it temporarily in memory so that you can relocate it in another location in the Code Editor or in another text editing software such as Notepad. Press Ctrl+X on your keyboard to perform the same function. Copies a selected portion of text and holds it temporarily in memory so that you can relocate it in another location in the Code Editor or in another text editing software like Notepad. Press Ctrl+C on your keyboard to perform the same function. Places text in specified location. Use in conjunction with Copy and Cut, after placing your mouse cursor on the location you would like to place your cut or copied text. Press Ctrl+V on your keyboard to perform the same function. 13

14 Table 2: Edit Menu Menu Selection Select All Find Replace Reserved Words List Linear Equation (Code) Description Selects (highlights) the entire text in your window. Press Ctrl+A on your keyboard to perform the same function. Opens a searching tool that allows you to search text in your window for every entry of a word or character that you enter. This is very useful when try to debug a code as you can type in the name of a variable or constant and find every instance in which it is used for example. Press Ctrl+F on your keyboard to perform the same function. Works in conjunction with the Find function. It allows you to replace whatever you find with the text that you enter. You may also choose to replace all if you would like a quick modification of all instances. Press Ctrl+H on your keyboard to perform the same function. Care should be taken when using this function so as not to replace correct portions of the program. Displays the Reserved Words list. Press Ctrl+Space Bar on your keyboard to perform the same function (while in the code window). If you start typing a reserved word and then access the reserved words list, it immediately highlights the first word in the list that starts with the same letters you have typed. Displays a pop-up to facilitate the coding of PID Loops. This window generates the mathematical equations that govern the output of the controller according to parameters entered by you. Clicking on the Generate button displays two equations that you may insert into your code. Clicking on Reset Values clears all the fields in the window (Figure 7). Figure 7: Linear Equation Tool 14

15 Settings Menu The Settings menu contains Data Logging and Advanced User. Data Logging, also know as Trending, opens a window that allows you to configure the number of logs (and the number of entries) in the controller. The maximum number of log entries allowed is 12,288. The maximum number of log files allowed is 24. Under this configuration, 12,288/24 (512) entries are in each log file. If you change the number of log files to 12, then you have a maximum of 1,024 entries in each log file. Advanced User is available to users who have advanced knowledge of Echelon Corporation s protocols. When you enable this feature, it allows you to work on configuring the device without communicating the programming to the controller (offline). Use the Download all to device and save command to apply your new configuration to the controller. Features appear on the File menu when Advanced Users is enabled. Tools Menu Figure 8: Log Dialog Box The Tools menu contains all the commands relevant to uploading and downloading code to the controller, checking the status of the code in the controller, uploading logs, and checking for syntax errors before loading the code onto the controller from the computer. Figure 9: Tools Menu 15

16 Table 3: Tools Menu Menu Selection Analyze Code Compile Code Compile and Load All Backup on Compile View Compiled Code Upload Logs Code Status (Device) Read Code (Device) Synchronize Description Debugs your code and checks it for syntax errors. The function searches the entire text, and for every error it finds, it returns an error message that includes the line number of the error. Also the error itself is highlighted in black. Once you run this function and no errors are in the code, it gives you a message saying this. Then your code is ready to download to the controller. Press F6 on your keyboard to perform the Analyze Code command. Analyzes the code (see Analyze Code), and after the code is error free it downloads only the BASIC code to the device. The status of the transmission appears in the status bar at the bottom of the screen. Press Ctrl+F6 on your keyboard to perform the same command. Analyzes the code (see above), and after the code is error free it downloads the BASIC code and all the other configuration properties (such as variables, inputs, outputs, NVI, and NVO) to the device. The status of the transmission appears in the status bar at the bottom of the screen. Performs an automatic backup of the code every time it is compiled. A check mark indicates this feature is enabled. Displays the compiled code in a pop-up window, when checked. Opens a window, which allows you to select and subsequently upload logs from the controller. The configured logs appear with the data type they are monitoring in the Item column. In Figure 10, only the first log is configured and, therefore, is the only one containing any data. Click Read Info. You can display the first time/date on which the log started and the last date at which it recorded any data, as well as the number of entries within the log. Click on Upload to display all the entries in the lower window, along with the date/time, value, and the data type that it came from (item). Checks the status of the code inside the controller and displays a window stating whether the code is running or not. If the code is running, then you have the option of stopping the code. If the code is not running, then you have the option of restarting the program from the top. This command can be useful if you see that your application is malfunctioning, and you want to stop all commands originating from the device while you troubleshoot your code (Figure 11). Displays the compiled code that is currently in the controller in a pop-up window. Displays a comparison between the database in the controller and that on your computer. Displays the result of the comparison in a window, along with the option for synchronizing either database using the other as a source. If you choose Download to Device then the wizard writes the data into the controller using the database on the computer as the source. The opposite is true for Upload from Device (Figure 11). 16

17 Figure 10: Log Upload Screen Figure 11: Code Status Dialog Box 17

18 Figure 12: Synchronize Options Window Windows Menu The Windows menu contains commands that visually organize your display windows. Table 4: Windows Menu Field Description Tile Horizontally Tile Vertically Figure 13: Windows Menu Arranges the windows so that they are positioned from top to bottom. All windows automatically resize to fit within the right panel of the main window while maximizing the width of each window. Arranges the windows so that they are positioned from left to right. All windows automatically resize to fit within the right panel of the main window while maximizing the height of each window. 18

19 Toolbar The items in the toolbar are graphical icons that represent shortcuts to commands available in the menus. This is to save you time when performing the most common functions. Table 5 describes the Toolbar. Table 5: Toolbar Menu Icon Description Figure 14: Toolbar Save All: Saves all current configurations. Prints: Prints the currently displayed information. Find: Locates all instances of key word you enter. Linear Equation: Creates a linear equation. Tile Horizontally: Horizontally tiles the display. Tile Vertically: Vertically tiles the display. Synchronize: Synchronizes the display. Reset: Assigns a zero value to all variables, inputs, outputs, timers, controllers, and optimum starts. A device reset is needed when the Input or Output Hardware settings have been changed. Whenever you change any of these settings, you are prompted to reset your device immediately or to reset it manually later. If you choose to reset manually, you must either click on the reset icon or press the reset button on the device. Error: Displays any error messages that have occurred. Help: Opens the Free Programmable Tool Online Help. 19

20 Refreshing Values/Data You can refresh values and data of internal points and network variables by clicking on the refresh button located in the upper left corner (Figure 15). When you click Refresh, the latest values are retrieved from the controller and appear for the selected feature. Figure 15: Refresh Button Advanced User Right-Click Menu The right-click menu is only available if you enable the Advanced user option from the Settings menu. The right-click menu displays commands available for the internal points of the free programmable controller (Figure 16). Figure 16: Advanced User Right-Click Menu 20

21 Main Window Internal Points Module This section describes all the elements of the Internal Points module. To access the screen that shows the Internal Points, click on the menu in the left side where it says Internal Points. Four windows are in the main display window, each representing an internal point type. To configure any of the internal points, simply double-click the point and the relevant configuration window appears. For example, to configure Variable 11, double-click it. Screen captures of the configuration windows of the internal points are provided along with a functional description of each. Figure 17: Internal Points Window Software Configuration The sections which follow show the step-by-step process of configuring all internal point types. Constants Constants are data holders that contain read-only fixed values. You can redefine the constants during execution. You may define the Label, Value, Unit and Description. When typed into the code, constants have a burgundy font color. Constants cannot be written to; they are read only. 21

22 To access this configuration window, double-click the desired Constant from the internal points main window, in Figure 18 it is Constant #5. Table 6 describes the Constant Configuration Dialog Box. Table 6: Constant Configuration Dialog Box Field Description Label Value Units Description Inputs Figure 18: Constant Configuration Dialog Box Displays the user definable text label of the constant. This label is used to refer to the constant in the code. Displays the constant value. Displays the engineering units of the constant. Displays a description of the constant. Inputs are Data holders containing values received from physical input points, such as the temperature reading from a temperature. Inputs are read only data types. Users may define the Label, Unit, and Description. There is also a manual option to set a value for testing purposes, which when checked, forces the input to assume the value that you enter in the Value field. The configuration of the type of input is done in the Hardware Configuration window. The Commissioned flag can be checked when the point is verified by the person installing the system. It is just a marker for record purposes. 22

23 When typed into the code, inputs have a red font color. Inputs cannot be written to. To access the inputs configuration window, double-click the desired Input from the internal points main window (Figure 19). Figure 19: Input Configuration Dialog Box 23

24 Outputs Outputs are data holders containing values being sent through the physical output points. You can define Label, Unit, and Description. There is also a manual option to set a value for testing purposes, which when checked, forces the output to take the value that you enter in the Value field. The configuration of the type of output is done in the Hardware Configuration window. The Commissioned flag can be checked when the point is verified by the person installing the system. It is just a marker for recording purposes. When typed into the code, Outputs have a pink color. You can read and write to Outputs (Figure 20). Figure 20: Output Configuration Dialog Box Variables Variables are Data holders containing dynamic values assigned during program execution. You may define Label, Unit, and Description. There is also a manual option to set a value for testing purposes, which when checked, forces the output to take the value that you enter in the Value field. 24

25 When typed into the code, Variables have a blue color. You can read and write to Variables (Figure 21). Figure 21: Variable Dialog Box 25

26 Hardware Configuration The Hardware Configuration module of the wizard deals with defining the hardware types of the inputs and outputs on a device, and some related configuration options. Two sections are in this module: Input Parameters and Output Parameters. To access the Hardware Configuration module, click on it in the menu in the left-hand window. The number of Inputs and Outputs that can be configured is automatically detected by the wizard and corresponds with the actual number of Inputs and Outputs on the device. Figure 22: Hardware Configuration Main Window 26

27 Input Parameters Configuration To configure an Input Parameter, double-click the type. Figure 23 appears with all the configuration options. Table 7: Input Parameters Field Description Type Rising/Falling Edge Scale Min/Max Input Min/Max Correction Filter (0% to 99%) Override Period (Min) Unit Figure 23: Input Parameter Dialog Box Displays the type of hardware that is connected to the Input on the device. See Figure 23. Fields appear only when a Pulse input is selected in the Type field. You can assign numeric values (as required by the hardware specifications) to the rising and falling edges of the pulse and their total is the total pulse count. Allows you to define the final input scale. If you have a 0-10 V input, you may set your Scale Min to 0 and your Scale Max to 100. A reading of 0 V would give you a reading of 0, and a reading of 1 V would give you a reading of 10. Allows you to define the input range to which to apply the scale to. For example, if you are using equipment with a limit of 5 V, you can set your Input Max to 5 and your Min to 0. That way all input values are within that range. Allows you to enter an offset for the input value. Allows you to enter a value, which the wizard uses to filter the input signal from any noise or distortion if the input wires run close to an electrical source. (100 - the filter percentage) is multiplied by the difference between two consecutive input readings, and the result is added to the first reading and become the second reading. If, for example, your filter value is 30%, your first reading is 10, and your second reading is 20, then your input value becomes 10 + ((20-10) x ( )) = 17. Thus, 17 is the second reading and NOT 20. Allows you to enter the time for the system to go into occupied mode if the override button is pressed. Displays engineering units of the field. 27

28 Input Type Note: It is imperative to consult the hardware installation guide of each controller for instructions on hardware and jumper configurations as this document covers the software side only. THR 10k TYPE II 10k ohms thermistors used in space temperature sensors or duct temperature sensors. THR 10k TYPE III 10k ohms thermistors used in space temperature sensors or duct temperature sensors. Differs from TYPE II in the resistance curve that it employs. Note: The 10k thermistors have a Negative Temperature Curve (NTC). Table 8 describes the NTC behavior often used with an occupancy override push button as part of the room sensor. Table 8: 10k Thermistors NTC Circuit Type Time Period Value Short Circuit/Override < 5 seconds Override = ON > 5 seconds Override = OFF > 15 seconds Input = Open POT 10k 10k ohms potentiometer used as setpoint offset (slide bar). Configured using potentiometer tool. POT 100k 100k ohms potentiometer used as setpoint offset (slide bar). Differs from 10k in resistance scale. Configured using potentiometer tool. RTD 1k TYPE 85 1k thermistor used in space temperature sensors. This type of sensor is particularly sensitive to noise. It is important to note that the 10k thermistors have a Positive Temperature Curve (PTC). Table 9 describes the PTC behavior often used with an occupancy override push button as part of the room sensor. Table 9: 10k Thermistors PTC Circuit Type Time Period Value Short Circuit/Override < 5 seconds Override = ON > 5 seconds Override = OFF > 15 seconds Input = Open

29 4 to 20 ma Analog Input Current inputs require an external power supply either on the sensor or wired in series with the sensor. To construct the current input, a 249 ohm resistor is installed on the controllers input terminals. Zero to 10 VDC Analog Input This input type requires a 24 VAC external power supply, and it is a 3 wire input with high impedance. This type of input can be modulated using the Scale Min./ Max., Input Min./Input Max. fields in the configuration window. Note that the modulation is a linear one between two points. Digital A switch, this is sometimes called dry contact that can also accept other electronic switches like an open drain or open collector. Occupied switches, bypass switches, and window switches are all examples of digital inputs. Pulse A pulse input is comprised of a rising edge and a falling edge. Values can be assigned to each. Upon completion of a cycle (rising edge + falling edge) their combined value is assigned to the pulse. 5V Rising Edge Falling Edge 0V sec THR PT100 Figure 24: Pulse Input Example A 100 ohm platinum thermistor used as space temperature sensors or duct temperature sensors. The 100 ohm platinum thermistors have a Positive Temperature Curve (PTC). Table 10 describes the behavior of the PTC. Table 10: PTC Behavior Circuit Type Time Period Value Short Circuit/Override < 5 seconds Override = ON > 5 seconds Override = OFF > 15 seconds Input = Open

30 The THR PT100 comes with a built-in filter. The filter field is grayed out if you are using the free programmable controllers (Figure 23). Potentiometer Use the potentiometer button to configure the sensitivity of a potentiometer input (either 10k or 100k). Figure 25 appears. Figure 25 represents a slide bar that is assigned a range of -2 to 2 degrees. When the bar is slid all the way to the heating side, 2 degrees are added to the setpoint, and vice versa. For this to work, each temperature step has to be assigned a corresponding resistance. By inputting -20 and 20 (corresponds to -2 and 2 because all temperature displays in the wizard are in units of degrees x 10) and clicking on Generate, the potentiometer tool gives the correlation as seen in the second figure. You can input any range for the setpoint, and use the Put button to replace some of the temperature values and change the sensitivity of your slide bar (a common method is to put 4 or 5 of the middle resistances to 0, which makes the slide bar less sensitive in the middle area). Output Parameters Figure 25: Potentiometer Configuration Dialog Box To configure an output, double-click on the parameter, and Figure 26 appears. Outputs appear pink when you insert them into to the BASIC code. Figure 26: Output Parameter Dialog Box 30

31 Note: The Free Programming Wizard automatically detects the types of outputs available and displays them in the Type field. Please consult the hardware installation manual of the device you are trying to configure to find out exactly what types of outputs it supports. Output Type Table 11 describes the output types. When you have incorrect input or output parameters, it may lead to the malfunctioning of your system, even if your program is logically sound. Consult the respective controller installation instructions to avoid problems. Table 11: Analog Output Specifications Output Specification 0-10 VDC Voltage: 0 to 10 VDC when configured as an digital output 0-10 V output is a modulated output where you can assign a value between 0 and 100%, and the controller converts it into a voltage between 0 and 10 V. This type of output is usually used to control actuators ma Current: 4 to 20 ma 4 to 20 ma output is a modulated output where you can assign a value between 0 and 100%, and the controller converts it into a current between 4 and 20 ma. Digital Pulse Width Modulation (PWM) Input and Output Network Variables Networks The free programmable controllers have three digital output types: Relay output Triac output 12 Volt digital output The relay and triac output types are commonly used to control fans, heating, and cooling stages. The 12 Volt digital output is used to drive external power relays or external power triacs and allows you the ability to control the same type of equipment as the previous types. PWM is basically a digital output that is timed controlled. This option is only used with triac or 12 Volt digital output types. The only parameter you can configure is the PERIOD (configurable between 2 and 15 seconds). PWM is commonly used to control heating baseboards or heating states. It is a modulated output operating between 0 to 100%. For example, 10 minutes (600 seconds), output value = 75% (BASIC code). The output is ON for 450 seconds (75%) and OFF for 150 seconds (25%). Network Variables are one of the essential features of any LONWORKS network. They are what give the network the interoperability feature and the open network capability. The most popular way of using NVIs and NVOs is through binding an NVO on one device to an NVI on another device in the same network. This way information can be exchanged freely and easily between elements of the same network without the need to go through a master controller that would have to collect and distribute information. Binding of network variables is done through a network management tool (for example, Facility Explorer Workbench). Standard Network Variable Types (SNVTs) SNVTs facilitate interoperability by providing a well-defined interface for communication between devices made by different manufacturers. They are, of course, only intended to be used with LONWORKS networks. 31

32 You can learn more about SNVTs by reading the SNVT Master List, which is on the Echelon Web site: Before you configure SNVTs, It is important to understand the basics of LONWORKS network architecture and data transfer protocols. Configuring Figure 27 shows the main window of the Network Variable module. You can access this window by double-clicking Network Variable in the left window menu. To configure an individual NVI or NVO, all you have to do is double-click it and the configuration window appears. Click OK in both the NVI and NVO configuration windows to save the changes you have made in your database and in your controller. Figure 27: Network Variables Main Window 32

33 Network Variable Inputs (NVIs) Figure 28 appears when you double-click an NVI to configure it. You can configure the Label of the NVI and a Description of the NVI. Click Read to display the latest value of the network variable in the Value field. When you inset NVIs into the BASIC code, they appear a golden color. Figure 28: Network Variable Input Configuration Dialog Box You cannot use the Persistent option with an NVI if it is bound (using a network management tool such as Facility Explorer Workbench) to an NVO. 33

34 To change the SNVT Type, use the Changeable Nv Type view of the device in Facility Explorer. Figure 29 appears. Each SNVT type has its own format. When an NVI is bound to an NVO, they must have the same format for the data to be transmitted correctly. So, before changing the SNVT types you are using, please consult the SNVT Master List. Fan_in dedicated NVIs Figure 29: Changeable Nv Manager Two NVIs are dedicated to performing functions: 34

35 NviFP_17 (Selecting Fan In Hi and Lo) When you double-click this NVI to configure it, Figure 30 appears. Figure 30: Fan-In Hi, Lo Dialog Box You can configure the Label and Description. However, when the Enable option is checked, this NVI can be used to perform the function of selecting the highest and lowest values it receives from NVOs that are bound to it. You can then read these values by inserting the FAN_IN_HISEL, FAN_IN_LOWSEL commands into the code. It is important to note that the values obtained through this function are true (valid) only for the period specified by you in the High and Low Selection Validity Period. The default value for this period is 2 minutes but you can set it to any number of minutes, from 2 minutes up to 255 minutes. After the validity period passes, the values obtained through this function are evaluated anew without taking into account values from the previous validity period. To ensure the accuracy of the calculation, make sure that all your NVOs have an update rate, which is lower than the input validity period. 35

36 NviFP_18 (Averaging Fan In) When you double-click this NVI to configure it, Figure 31 appears. The configuration fields are described in Table 12. Table 12: Fan-In Average Parameters Fields Descriptions Negative/Positive Value Setpoint Offset Equivalent to 100% Input Validity Period Figure 31: Fan-In Average Dialog Box Displays the weighted value to your data in four fields. A normal mathematical average might not describe the situation as accurately as a weighted one where you can configure the weights. You can favor either heating or cooling, depending on the type of system and environment you are dealing with. Calculates Offset average for temperature values. You may select from a drop-down list of internal points. Use as a reference point to compare the incoming data to. Displays the temperature range above and below the setpoint that you wish to weigh. Displays the maximum period of time for which an NVO is included in calculating the average without being updated. To ensure the accuracy of the calculation, make sure that all your NVOs have an update rate that is lower than the input validity period. 36

37 You can configure the Label Description (Table 12). However, when the Enable option is checked, this NVI can be used to perform an averaging function on all the data it receives from NVOs of the same type that are bound to it. Two types of data can be averaged with this function: Percentage Average (Terminal Load values) and Offset Average (Temperature values). The maximum number of NVOs whose data can be included in the average is 128. Also, only one NVO per device is allowed to be bound to this NVI (nvifp_18). When inserted into the code, the function (FAN_IN_AVG) returns the raw numerical average of the data it has received. When you use the FAN_IN_AVG, use special care regarding the SNVT types you choose. The reason is that each SNVT type used by all LONMARK compliant networks (such as Johnson Controls) has a specific scale that it uses to transport the data across the network. The following is the scale for the two SNVT types used by FAN_IN_AVG: SNVT_lev_percent: Use if you are trying to calculate the percentage average (terminal load values). Its scale is 1/200. If you have 10 NVOs (must be on 10 different controllers) bound to nvifp_18, then in the value field of nvifp_18 you read a value equal to the average/200. The way to avoid this is to insert a multiplication factor of 200 into the code of each of the 10 controllers. So on Device1, we say VAR2 = VAR1 * 200, and then we set the NVO of that controller equal to VAR2. This way the value is multiplied by 200 in the code and then divided by 200 when it is transported through the network. Therefore, the value that you read in the value field next to nvifp_18 is the true value and not the raw one. Note: This multiplication factor of 200 is applied only when receiving data from a free programmable controller. LONMARK profile controllers (VAV-L, RTU-L) display the correct value without the need of a multiplication factor. SNVT_temp_p: Use if you are trying to calculate a weighted temperature average (temperature values). The scale is 1/100. To avoid a bad reading, insert a multiplication factor of 100 into the code of each of the controllers sending NVOs to nvifp_18. 37

38 Network Variable Outputs (NVOs) When you double-click an NVO, Figure 32 appears and allows you to configure the NVO. You are asked to define what Data (select from a list of all the internal points already configured in your device) the NVO carries across the network and also a Description. As with NVIs, NVOs follow SNVT types, and you can change the type by using the Changeable Nv Manager view in Facility Explorer. Reserved Words Reserved words are predefined system keywords, each representing a certain function or value. The reserved words list includes all of the functional elements of the BASIC code except for the Output Network Variables (NVOs). You are not allowed to modify these words nor the values nor functions they represent. The reserved words list is easily accessible when in the code window by pressing Ctrl and Space Bar simultaneously. Mathematical Operators All of the other elements of the BASIC code interact with each other using these mathematical operators. They fall into three categories as follows: Arithmetic Operators Table 13 describes the arithmetic operators. Table 13: Arithmetic Operators Operator Description Figure 32: Network Variable Output Configuration Dialog Box + Represents the addition operator. - Represents the subtraction operator. * Represents the multiplication operator. / Represents the division operator. 38

39 Comparative Operators (used only in IF statements) Table 14 describes the Comparative Operators (used only in IF statements). Table 14: Comparative Operators Operator Description > = Represents the greater than or equal to operator. < = Represents the less than or equal to operator. > Represents the greater than operator. < Represents the less than operator. = Represents the equal to operator.! = Represents the not equal to operator. Logical Operators (used only in IF statements) The following are logical operators: AND: logical operator for combining conditions. Returns TRUE or FALSE. OR: logical operator for alternative conditions. Returns TRUE or FALSE. The logical operator functions are shown in Table 15 and Table 16. Table 15: AND Logic Condition1 Logical Operative Condition2 Result 1 AND AND AND AND 0 0 Table 16: OR Logic Condition1 Logical Operative Condition2 Result 1 OR OR OR OR 0 0 Combined conditions are possible (again, only in the IF statement), with no more than three conditions per IF statement line. Combined conditions are evaluated from the left to the right and no double brackets are allowed. Table 17 shows how this works. Table 17: Combined Conditions Sample Logic Condition1 Logical Operative Condition2 Logical Operative Condition3 Result 1 AND 1 OR OR 0 AND AND 1 AND OR 0 OR

40 Note: All mathematical operators are evaluated from the left to the right; regular operator precedence does not apply. No brackets are allowed. Furthermore, no operators should be present to the left of the equal sign. For example: This example is to illustrate Data Type interaction using Mathematical Operators. Keep in mind that ALL Data Type declaration is done in the Graphic User Interface (GUI). Var_A = Input_B + Const_C * Var_D - Input_F / Var_E This expression is executed in such a way as if it was written as: Var_A = (((Input_B + Const_C) * Var_D) - Input_F) / Var_E As opposed to the following conventional operator precedence: Var_A = Input_B + (Const_C * Var_D) - (Input_F / Var_E) Remarks Remarks Definition Remarks are text components of any code. This type of code is not executed by the controller but guides the reader through the code and explain the sequence. For the controller to recognize remarks, they must be preceded by REM and a space. All the examples of code used in this document are explained through the use of comments. The color of remarks in the BASIC code is green. Example: REM<space>This is to show you how to write a remark in the BASIC code Chronological Reserved Words Chronological Reserved Words Definition Chronological Reserved words are meant to help you call a number of chronological items into your code for precise and efficient programming. Depending on which word you use, the program retrieves the value from the Real-Time Clock in the controller, so that the time or date you use in your code is accurate. Each of these words returns a numeric value to the code when used. It is also possible to use these words in conjunction with mathematical operators when assigning values to variables in your code. 40

41 You cannot change the value of these words in the code. The only way to change the date and time in the Real-Time Clock would be through the network management tool (Facility Explorer) or through RTC wizard. Table 18 is a list of these words along with a brief description. Table 18: Chronological Reserved Words Words Description DAY The day of the current MONTH and can be 1 to 31 depending on the month. DAYOFWEEK The day of the current WEEK. 0 (Sunday) through 6 (Saturday). HOUR The hour of the current DAY. 0 to 23. MINUTE The minute of the current HOUR. 0 to 59. MONTH The month of the current YEAR. 1 to 12. SECOND The second of the current MINUTE. 0 to 59. YEAR The current YEAR. 4 digits. Example Code: REM This piece of code will turn on a heating stage or cooling stage depending REM on the month of the year. If the month is between April and September, it REM turns on the cooling stage, if the month is between October and March REM then it turns on the heating stage IF (MONTH >= 4) AND (MONTH <= 9) COOLING_PERMISSION = ON HEATING_PERMISSION = OFF ELSE COOLING_PERMISSION = OFF HEATING_PERMISSION = ON ENDIF Built-In Commands Definition Built-in commands are common programming algorithms that are predefined in the Free Programming Wizard. An intuitive keyword (reserved word) is assigned to each built-in function so that you may insert it with ease into the code without any prior configuration. All built-in commands are reserved words. Built-in commands take on a pink color in the BASIC code. The following is a detailing of the Built-In Commands available in the Free Programming Wizard. Note: There is a coded example for each built-in Command. It is assumed that all the Data Types used in these examples have been created in the GUI. Also <sp> is used to indicate a space. Comments are used to explain the purpose of the code. 41

42 AVERAGE Table 19 describes the AVERAGE Built-in command. Table 19: AVERAGE Built-in Command Words Description Description Parameters Returns Syntax: RESULT<sp>=<sp>AVERAGE<sp>(<sp>PARAM1<sp> <sp>param10<sp>) Example Code: REM Calculate the average temperature of room 1, 2, and 3 REM Put the result in the variable AVG_TEMP AVG_TEMP = AVERAGE (RM_TEMP1 RM_TEMP2 RM_TEMP3) HISEL Calculates the average value of the provided parameters. Allows up to 12 parameters. Parameters can be of any Data Type. Represents the average value of all provided parameters. Table 20 describes the HISEL Built-in command. Table 20: HISEL Built-in Command Words Description Description Parameters Returns Finds the highest value among the provided parameters. Up to 12 parameters can be used with this function. Parameters can be of any Data Type. The highest value among all provided parameters. Syntax: RESULT<sp>=<sp>HISEL<sp>(PARAM1<sp> <sp>param10) Example Code: REM Evaluate the temperatures of room 1,2, and 3 REM Put the highest one in the variable HIGH_TEMP HIGH_TEMP = HISEL (RM_TEMP1 RM_TEMP2 RM_TEMP3) LOWSEL Table 21 describes the LOWSEL Built-in command. Table 21: HISEL Built-in Command Words Description Description Parameters Returns Calculates the lowest value among the provided parameters. Up to 12 parameters can be used with this function. Parameters can be of any Data Type. The lowest value among all provided parameters. 42

43 Syntax: RESULT<sp>=<sp>LOWSEL<sp>(PARAM1<sp> <sp>param10) Example Code: REM Evaluate the temperatures of room1, 2, and 3 REM Put the lowest one in the variable lowtemp LOW_TEMP = LOWSEL (RM_TEMP1 RM_TEMP2 RM_TEMP3) Note: Programming Tip: LOWSEL and HISEL functions can be used to evaluate binary values (0,1) as well. LOWSEL is used instead of the AND logical operator and HISEL is used instead of the OR logical operator for more efficient coding. LIMIT Table 22 describes the LIMIT Built-in command. Table 22: LIMIT Built-in Command Words Description Description Parameters Returns Evaluates the value of a data type and makes sure that it stays in the range defined by a high limit and a low limit. Input value: Value to be evaluated (can be any Data Type) Low limit: Lowest value of the desired value range. High limit: Highest value of the desired value range. Input value if the input value is within the value range. High limit if input value is greater than high limit. Low limit if input value is smaller than low limit. Syntax: RESULT<sp>=<sp>LIMIT<sp>(INPUT<sp>LOW_LIM<sp>HI_LIM) Example code: REM Make sure that the outside temperature is within REM a realistic range MY_OUT_TEMP = LIMIT (OUT_TEMP RECORD_LOW RECORD_HI) Note: It is also possible to use numbers to set the high and low values of the range. Table 23 shows the returned values of MY_OUT_TEMP (from the previous example code) in a number of different scenarios. Table 23: MY_OUT_TEMP Return Values OUT_TEMP RECORD_LOW RECORD_HI MY_OUT_TEMP

44 SWITCH Table 24 describes the SWITCH Built-in Command. Table 24: SWITCH Built-in Command Words Description Description Parameters Returns Determines whether a device should be ON or OFF based on the comparison results of the input value vs. the on and off criteria. Input value: Value to be evaluated (can be any Data Type) ON value: Comparison value for ON criteria. OFF value: Comparison value for OFF criteria. 1 (ON) or 0 (OFF) Note: ON and OFF are reserved words defined as constants. ON has a fixed value of 1 and OFF has a fixed value of 0. So if you say VAR1 = ON, that assigns a value of 1 to VAR1. Also, it is possible to use numbers to set the on and off values. Syntax: RESULT<sp>=<sp>SWITCH<sp>(INPUT<sp>ON_VAL<sp>OFF_VAL) The SWITCH function is a good example of how built-in functions can save you time in terms of programming. It is also a good example of how Conditional Execution can help you realize your project needs. The following code is the logical expression that is called when you use the SWITCH function. Also the flowchart on the following page illustrates the algorithm that is behind the SWITCH function. IF (ON_VAR > OFF_VAR) IF (INPUT_VAR >= ON_VAR) RESULT = ON ENDIF IF (INPUT_VAR <= OFF_VAR) RESULT = OFF ENDIF ELSE IF (INPUT_VAR <= ON_VAR) RESULT = ON ENDIF IF (INPUT_VAR >= OFF_VAR) RESULT = OFF ENDIF ENDIF 44

45 OFF_VAL COMPARE VALUES ON_VAL ON_VAL IS GREATER OFF_VAL COMPARE VALUES INPUT_VAR ON_VAL COMPARE VALUES INPUT_VAR INPUT_VAR IS SMALLER INPUT_VAR IS GREATER RESULT = OFF RESULT = ON OFF_VAL IS GREATER OFF_VAL COMPARE VALUES INPUT_VAR ON_VAL COMPARE VALUES INPUT_VAR INPUT_VAR IS GREATER INPUT_VAR IS SMALLER RESULT = OFF RESULT = ON Figure 33: Switch Function Logic Flowchart Example Code 1: ON_VAR is greater than OFF_VAR (for example, for cooling) REM START_LIMIT is 2 degrees and STOP_LIMIT is -2 degrees. REM Evaluate the temperature differential ROOM_DIFF. Turn the 45

46 REM AC on if it is greater than START_LIMIT. If it is smaller than REM STOP_LIMIT, turn the AC off. If it is within range, keep the REM current AC status AC = SWITCH (ROOM_DIFF STAR_LIMIT STOP_LIMIT) Table 25 shows the value of AC and how it is determined using the SWITCH function, according to the example code 1 above. Table 25: AC Value from Example Code 1 ROOM_DIFF START_LIMIT STOP_LIMIT AC Depending on the initial value of AC, because ROOM_DIFF is within the range of START_LIMIT and STOP_LIMIT, no action is taken. So if AC is 0 initially, it remains 0, and if it was 1, it remains 1. Example Code 2: ON_VAR is smaller than OFF_VAR (for example, for heating) REM START_LIMIT is -2 degrees and STOP_LIMIT is 2 degrees. REM Evaluate the temperature differential ROOM_DIFF. Turn the REM HEATER on if it is smaller than START_LIMIT. If it is greater REM than STOP_LIMIT, turn the heater off. If it is within range, keep REM the current status of the HEATER HEATER = SWITCH (ROOM_DIFF START_LIMIT STOP_LIMIT) Table 26 shows the value of HEATER and how it is determined using the SWITCH function, according to the example code 2 above. CLEAR (ON) or (OFF) Table 26: AC Value from Example Code 1 ROOM_DIFF START_LIMIT STOP_LIMIT AC (ON) or (OFF) Table 27 describes the CLEAR built-in command. Table 27: CLEAR Command Words Description Description Parameters Returns Resets the counting of the pulse of the input peripheral. Reset the value of the controller. None None 46

47 Syntax: CLEAR<sp>INPUT Example Code: REM Reset the counting of the pulse of the electric kwh meter CLEAR KWH_PULSE FAN_IN_AV Table 28 describes the FAN_IN_AV built-in command. Table 28: FAN_IN_AV Command Words Description Description Parameters Returns Calculates the average weighted percentage value of the number of NVOs bound to nvifp_18. Represents nvifp_18: this is the only NVI the function operates. Displays a percentage value (terminal load). Syntax: RESULT<sp>=<sp>FAN_IN_AVG Example Code: REM Calculates the weighted average percentage terminal load of a number REM of VAVs, each having an NVO (that reports that VAVs terminal load) REM bound to nvifp_18 which is given the label LOAD_AVG_NVI in GUI LOAD_VAR = FAN_IN_AVG FAN_IN_HISEL and FAN_IN_LOWSEL Table 29 describes the FAN_IN_HISEL and FAN_IN_LOWSEL built-in Command. Table 29: FAN_IN_HISEL and FAN_IN_LOWSEL Command Words Description Description Parameters Returns Compares the value of all NVOs bound to nvifp_17 and returns the highest value if you use FAN_IN_HISEL and the lowest value if you use FAN_IN_LOWSEL. Represents nvifp_17: this is the only NVI the function operates. Displays a percentage value (terminal load). Syntax: RESULT<sp>=<sp>FAN_IN_HISEL OR RESULT<sp>=<sp>FAN_IN_LOWSEL Example Code (HISEL): REM Calculates the highest percentage terminal load of a number 47

48 REM of VAVs, each having an NVO (that reports that VAVs terminal load) bound to nvifp_18 HI_LOAD_VAR = FAN_IN_HISEL SQRT END Table 30 describes the END built-in Command. Table 30: END Command Words Description Description Parameters Returns Informs the controller that the program is finished and returns it to the top of the program to run it again. None None Syntax: END Note: In the code window of the Free Programmable Wizard, you find END already placed. So while writing your program, make sure that the END function is always at the bottom; this is to keep you from forgetting to end the program as every program must finish with an END command. SQRT applies only to the LX-VAVCF-1 controller. Table 31: SQRT Functions SQRT Command Function Description Parameters Returns Calculates the square root of a value. Represents the variable or value to be square rooted. The divisor of the calculated value (1, 10, 100, 1000). Example: 1000 = thousandth of value Displays the square root of the value respecting the precision. Syntax VAR_SQRT = SQRT (VAR<sp>DIVISOR) Table 32 shows an example if you want to calculate the square root of pressure (in thousandth of "WC) for the flow. Table 32: SQRT Pressure Example SQRT Command Descriptions Value PRESSURE = 500 (representing 0.5 WC) WC = inches of Water Column Syntax PRESSURE_SQRT = (PRESSURE 1000) Results PRESSURE_SQRT = 707 (representing WC) 48

49 HWOUT_OVR_VALUEx Only the free programmable controllers with an HOA switch have the HWOUT_OVR_VALUEx option. If the HOA switch option is not available, the return value of the controller s outputs is automatically 1 (Auto mode). Table 33 describes the HWOUT_OVR_VALUEx functions. Table 33: HWOUT_OVR_VALUEx Functions HWOUT_OVR_VALUEx Command Description Parameters Returns Function Reads the voltage level of the output as defined by the HOA potentiometer for that output. The last character of the reserved word is the number of the output to read. None Displays 0 (VDC) to 120 (12.0 VDC) Syntax: HWOUT_OVR_MODE5 Example Code (Output 5): REM Turn on the pump if the HOA state of output 5 is in Auto mode IF (HWOUT_OVR_MODE5 = 1) PUMP = ON ENDIF Table 34: HWOUT_OVR_MODEx Functions HWOUT_OVR_MODEx Function Command Description Parameters Returns Reads the HOA state (mode) of the output. The last character of the reserved word is the number of the output read. None Displays 0 (VDC) to 120 (12.0 VDC) Syntax: HWOUT_OVR_VALUE3 Example Code (Output 3): REM Turn on the pump if the voltage level of output 3 = 60 VDC IF (HWOUT_OVR_VALUE3 = 60) PUMP = ON ENDIF 49

50 OUT_MODE_x Table 35 describes OUT_MODE_x parameters. Table 35: OUT_MODE_x Functions OUT_MODE_x Command Description Parameters Returns Syntax HWOUT_OVR_VALUE3 REM Turn off the pump if output 2 is REM in manual mode. IF (OUT_MODE_2 = 1) PUMP = OFF ENDIF IF Statement (Conditional Execution) Syntax and Logic Function Reads whether the output is in Manual/Automatic mode. The last character of the reserved word is the number of the output read (for example, to read the HOA state of output 5, enter OUT_MODE_5). None 0 = Off Mode 1 = Auto Mode 2 = Hand (manual) Mode Common to all high level programming languages, the IF statement allows the programmer to execute code based on the result of the evaluation of a condition(s). The evaluation returns a binary, 1 for TRUE and 0 for FALSE. So if TRUE, the processor executes the associated code. If FALSE, then the processor executes code that is listed under the ELSE part of the IF statement as shown below, or if there is no ELSE then the processor leaves the Conditional Loop and continues executing the code. The IF statement is a Built-In Function and therefore is a part of the reserved words list. It is described in a separate section because of its importance. The IF statement used in the Free Programming Wizard has the following syntax: IF<sp>(<sp>condition<sp>) <statement block> ELSE <statement block> ENDIF Note: It is not necessary to have an ELSE section (alternative condition) in your IF statement. 50

51 A condition is normally made using a Comparative Operator. Logical Operators are used to combine conditions. This appears in the examples. It is also possible to put an IF statement within the statement block of another IF statement. These are called nested IFs. Note: The ELSE part of the IF statement is optional. It is normally used to execute alternate code if the condition returns a FALSE value. The following rules apply to the IF statement: No more than three conditions (combined using AND, OR) per IF statement line. No double-brackets are allowed and conditions used in the IF statement are evaluated from the left to the right. No more than three nested IFs in each primary IF statement. It is also recommended that the statement block of each IF statement be indented to make it easier to read and to understand. 51

52 Sample Codes This section shows three sample codes for the IF statement. Example Code 1 REM When using the if statement, the condition must always be in parentheses. REM The ELSE section of the code is carried out if the REM IF condition is FALSE SO if CONDITION1=ON then OUTPUT1 will be REM assigned a value of 1(ON), if REM CONDITION1=OFF then OUTPUT1 will be assigned a value REM REM 0(OFF). The IF loop ends with the ENDIF command IF (CONDITION1 = ON) OUTPUT1 = ON ELSE OUTPUT1 = OFF ENDIF Example Code 2 (Combined Conditions) REM Here we have three combined conditions. First the processor performs REM the OR comparison and then with the result of that comparison it does REM the AND comparison. If this entire process returns a 1, then OUTPUT1 REM will be ON, if it returns a 0 then OUTPUT1 will be OFF IF (CONDI1 = ON) OR (CONDI2 = OFF) AND (CONDI3 = ON) OUTPUT1 = ON ELSE OUTPUT1 = OFF ENDIF 52

53 Example Code 3 (Nested IF Loop) REM Here there is one nested IF loop in the original loop. The processor first REM checks if the initial condition is TRUE before checking the condition of REM the second loop, if it is FALSE then it executes the ELSE section of the REM first loop. The above process is repeated for every nested IF loop IF (CONDITION1 = ON) IF (CONDITION2 = ON) OUTPUT1 = ON OUTPUT2 = ON ELSE OUTPUT1 = ON OUTPUT2 = OFF ENDIF ELSE IF (CONDITION2 = ON) OUTPUT1 = OFF OUTPUT2 = ON ELSE OUTPUT1 = OFF OUTPUT2 = OFF ENDIF ENDIF Controllers-Proportional-Integral-Derivative (PID) Loop Definition and Logic Traditional control methods incorporate a simple On/Off method. This method uses a setpoint to determine the device state. For example, if the temperature in a room is measured to be below the setpoint, then the device goes to 100% output (On), and if the temperature is measured to be above the setpoint, then the device goes to 0% output (Off). This is a very wasteful method of control in terms of energy, and it was the desire for a more energy efficient method that finally led to the development of the PID loop. This is a type of feedback controller whose output, a Control Variable (CV), is generally based on the error between some user-defined Set Point (SP) and some measured Process Variable (PV). PID is a control algorithm used for the control of almost all loops in the process industries and is also the basis for many advanced control algorithms and strategies. 53

54 As mentioned, there are three main parts in a PID loop, keeping in mind that it is possible to make a control loop using any combination of the three or using only one element as well. Figure 34: Controller (PID) Configuration Dialog Box Proportional This is the first and most basic element of the PID loop, the equation that governs it is simple: Error = measurement - setpoint (direct action) Or Error = setpoint - measurement (reverse action) Note: The action may be either direct or reverse. In a direct acting control loop, an increase in the process measurement causes an increase in the output of the device. So the proportional only equation would be: Output = proportional gain * error + bias Proportional Gain: is a multiplication factor that is user definable (see Proportional Band) and that adds weight to the proportional part of the PID loop Bias: is defined as the default percentage of output upon reset of the device 54

55 Dead Band: is defined as the range around the setpoint which does not affect an action from the controller. So if your setpoint is 22 degrees C for example, and your dead band is 2 degrees C, then your controller does not react to any change in the setpoint that is between 21 degrees C and 23 degrees C. In the Free Programmable Wizard, you must configure the Proportional Band. The Proportional Band and the Gain are related Proportional Band = 100% / Gain Proportional Band is the amount the input would have to change to cause the output to move from 0 to 100% (or vice versa). So we can rewrite the proportional output equation as follows: Output = (100/proportional gain) * error + bias With proportional only control, the controller does not bring the process measurement to the setpoint without a manual adjustment to the bias (or manual reset) term of the equation. In the early days of control, the operator (observing an offset in the control loop) would correct the offset by manually resetting the controller (adjusting the bias). When the Dead Band is assigned a value on the PID loop, the value of the Proportional Band increases by the same value. If your setpoint is 22 and your original proportional band (without the use of a dead band) is 4 degrees, then the output goes to 100%. If the temperature reading in the room is more than 24, then it goes to 0% when the reading is lower than

56 However, if you configure your Dead Band (see above) to 2 degrees, then your New Proportional Band becomes 6 degrees (4 + 2). This means that the output goes to 100% only when the temperature reading in the room goes above 25 degrees, and only goes to zero when the reading goes below 19 degrees. Figure 35 illustrates this behavior. % 100 Output without DeadBand Output with DeadBand 50 Output 0 Temp Dead Band Deg. C Original Proportional Band New Proportional Band Figure 35: New Proportional Band Example Integral Rather than require that the operator manually reset the control loop whenever a load change occurs, control functions were developed to automatically reset the controller by adjusting the bias term whenever an error occurred. The automatic reset is also known as simply the reset or the integral. This is represented in the Free Programmable Wizard by defining the Integral Gain and the Integral Time: Integral Gain: is a multiplication factor that is user definable and that adds weight to the integral part of the PID loop. Integral Time: is a user definable value that is measured in seconds. It is the cycle period for the integral part of the PID loop. So if the Integral Time is 30 seconds, then the Integral part of the PID loop is calculated every 30 seconds. The equation for the Integral part of the loop only is: Output = Integral Gain/Internal Time * Integral Error dt So the equation for a PI (proportional-integral) loop is: Output = (Proportional Gain * Error) + ((Integral Gain * Error)/Integral Time) 56

57 There is no Proportional Band in the Integral or Derivative parts of the loop, only in the Proportionate. The Integral or Derivative parts of the loop use the Gain. Derivative The third term of the PID control loop is derivative. The derivative term looks at the rate of change. The derivative function can either use the time derivative of the error (de/dt), which would include changes in setpoint, or of the measurement only, excluding setpoint changes. The equation for the derivative part is: Output = Derivative Gain * Derivative Time * (de/dt) The Derivative Time is also measured in seconds. So to put it all together, the output of the PID loop is the sum of all three parts (if they are all used): Output = Proportional + Integral + Derivative Setpoint (SP) DG*DT *d/dt Error=(SP) - (MV) PG SUM OUTPUT Measured Variable (MV) (IG/IT) * dt Figure 36: PID Logic Flowchart 57

58 Tuning the PID Loop Figure 37 describes how to tun a PID loop. Figure 38 shows the PID Response graph. Ultimate Sensitivity Method The goal is to achieve a marginally stable controller response Repeat the testing until you achieve and record a marginally stable response. TEST 1 Closed Loop (Loop In Automatic ) 1. Choose any Proportional Band setting. Place INTEGRAL at maximum time (smallest value) and place DERIVATIVE at minimum value or turn it off completely. 2. Make a 10% change in SETPOINT (SP). 3. Record the PROCESS VARIABLE (PV) and CONTROLLER OUTPUT (CO) responses. If process becomes unstable, place the loop in MANUAL and maintain control as necessary. 4. If recorded response produces a stable (lagging) response, proceed to Test 2. If recorded response produces an unstable (leading) response, proceed to Test 3. TEST 2 1. Double the GAIN setting (leave INTEGRAL and DERIVATIVE the same as in Test 1). 2. Make a 10% change in SP. 3. Record the PV and CO responses. If process becomes unstable, place the loop in MANUAL and maintain control as necessary. 4. If recorded response produces a stable (lagging) response, repeat Test 2. If recorded response produces an unstable (leading) response, proceed to Test 3. TEST 3 1. Half the GAIN setting (leave INTEGRAL and DERIVATIVE the same as in Test 1 and Test 2). 2. Make a 10% change in SP. 3. Record the PV and CO responses. If process becomes unstable, place the loop in MANUAL and maintain control as necessary. 4. If recorded response produces a stable (lagging) response, repeat Test 2. If recorded response produces an unstable (leading) response, repeat to Test 3. Figure 37: Tuning a PID Loop 58

59 Figure 38: PID Response Graph Logs Sample Code Example code: REM Here the VALVE value is equal to the value of the controller. All REM controllers are configured through the GUI. The controller compares REM the value of the input vs. the value of the setpoint. The valve would be REM in cooling if the controller is in direct mode, and in heating if it is in REM reverse mode. VALVE = CO1 Note: To insert the controller values into your code, use the reserved word that corresponds to your controller. So if you configure controller # 8 in your GUI, then use CO8 in your code. Ten controllers correspond to CO1 to CO10. Definition and Logic As a system administrator, it is crucial for you to have precise and up-to-date information at your disposal for effective building management. Whether it is for keeping system operation history, tuning system variables, or troubleshooting, the log tool in the Free Programming Wizard is of great value to you. 59

60 A good example of how logs can be used is in monitoring the room temperature of a computer room that houses a mainframe. These supercomputers require a controlled temperature environment in order to function properly. As a system integrator you would like to show the building manager that the system you have installed and programmed can meet his temperature control requirements. Using one of the logs in the Free Programming Wizard, you can record the temperature readings of the temperature sensor in the room for a period of time and present the raw data to the building manager as proof of your system s capabilities. Up to 24 logs are available in the Free Programming Wizard. The total logging capacity is 12,288 events. If you choose to monitor 24 logs, you have a capacity of 512 events recorded per log. If you monitor 12 logs, you have 1,024 events recorded per log, and so on. Whenever a log reaches its capacity, it performs a wrap around and saves the new values over the old ones starting with the first. There are two ways of data logging in the Log tool. The first one uses a differential that is added to or subtracted from the last recorded value, and if the next read value is greater than or equal to the higher value (or lower than or equal to the lower value), then the log records that value. So if your setpoint is 23 degrees C, and your differential is 2 degrees, then your log records any value that is above or equal to 25 (or lower than or equal to 21). The other way of logging uses a time differential. So if your time differential is set to 300 seconds (it is in multiples of 60 only when 24 logs are configured, multiples of 30 when 12 logs are configured), then the log records the data value every 300 seconds. It is also possible to combine the two data logging methods using the AND/OR modes in the configuration window. So if AND is selected, both the time and the differential must occur for the data to be recorded. If OR is used then only one of the two must be satisfied in order for the log to record the value. Note: If either the Differential or the Time is set to zero, then that parameter disables. Log data is stored in the Flash memory (nonvolatile) on your controller. When you upload the stored data from the controller, it is saved in a Microsoft Access file on your hard disk. Logs cannot be inserted into the basic code. 60

61 You configure each log through the GUI. The setup of each log is split into two sections: Configuration and Format Parameters. Figure 39: Main Log Configuration Dialog Box Configuration Configuration is part of the log setup. Table 36 describes what you configure. Table 36: Configuration Parameter Description Data Differential Time Mode Displays the data type that the log monitors. Displays the data differential. If the new data + (+/-) differential is greater than or equal to the last recorded value or smaller than or equal to the last recorded value, then the log records this value. Represents the time differential. It is in multiples of 60 (depending on the number of configured logs) seconds only. So every time this amount of time passes, the log records another value. Represents that the AND/OR option is selected. If AND is selected, then the Differential and the Time have to be satisfied in order for the log to record a value. If OR is selected then only one of the two has to be satisfied for the log to record a value. 61

62 Format Parameters In this section, you can configure parameters that are recorded in the log file along with the raw data. These parameters are intended to help read the stored data. The general format is: (Multiplier * Data) + Offset This transformation is very useful for data processing. For example, if you record your data in degrees Celsius and you would like to display them in degrees Fahrenheit, then you can put your multiplier to 1.8 and your offset to 32. The user may configure the parameters described in Table 37. All the parameters are saved in the Access file. Table 37: Configuration Parameter Description Multiplier Offset Unit Timers Description Definition and Logic Represents the numeric value that is multiplied by the data. Represents a numeric value (positive or negative) that is added to the result of the multiplication of the data by the multiplier. Allows you to specify the unit for the logged data. Allows you to enter a description of the logged data. Timers are a programming utility used to count the time elapsed since the equipment or variable launching. Timer can count in seconds, minutes, and hours. The maximum number the timer counts to is 32,767 irrespective of the time unit used. When you reach the number, the timer stops functioning until it is manually reset. If the Data Type the timer is tracking has a value of zero, the timer automatically stops and continues from the last recorded time when the value goes above zero again. For example, if your variable drops from 5 to 0 after 2 minutes of operation, then the timer stops counting at 2 minutes. If after 10 minutes from reaching 0 your variable goes back up to 3, then your timer starts counting again from 2 minutes. The 10 minute lag does not record. 62

63 Timers can be inserted into the BASIC code using the reserved words TIMER1 through TIMER15, which represent the 15 configurable timers available. When you configure the timers in the GUI, you configure the parameters described in Table 38. Figure 40: Timer Configuration Dialog Box Table 38: Timer Configuration Window Parameter Description Data Allows you to select which one of your configured Data Types you want your timer to track. The allowed Data Types that can be associated with a timer are Inputs, Outputs, and Variables. The Data Types must be configured prior to being associated with a timer or else they do not appear. You select from a pull-down menu. Type Asks you to specify the time unit (seconds, minutes, hours). You select from a pull-down menu. Value Displays the current (or last) value of the timer. This field can also be used in conjunction with the set function to manually enter a value for the timer. Set Assigns whatever value is currently in the Value field to the timer. So if your Timer currently has a value of 300 seconds and you would like to set it to 100, simply enter 100 in the Value field and click on Set. 63

64 Example code: REM Here if START_DEMAND becomes ON, the controller waits for a delay REM before initiating the START_STOP. Thus when START_DEMAND goes REM ON then START_DELAY goes to ON, which activates TIMER1. When REM the START_DEMAND comes OFF again then START_DELAY goes to REM OFF also which makes TIMER1=0, When TIMER1 is more than 15 then REM the START_STOP goes to ON IF (START_DEMAND = ON) START_DELAY = ON ELSE START_DELAY = OFF TIMER1= 0 ENDIF IF (TIMER1 = 15) START_STOP = ON ELSE START_STOP = OFF ENDIF 64

65 Optimum Starts Definition and Logic Optimum starts are very useful if you want your system to follow occupancy patterns, or any other desired pattern. For example, an office building opens its doors to the staff at 7 A.M., and you know that it takes the system 1 hour to reach the desired temperature setpoint; then you would only reach the setpoint at 8 A.M. if you start the system at 7 A.M. This can be uncomfortable for the employees. The best thing would be to configure an optimum start in the Free Programming Wizard. The optimum start forces the system to go into occupancy mode enough time ahead of the scheduled starting time so that it can reach the desired starting setpoint. This way, the building is at or near the setpoint when the employees enter. In the configuration window of the Optimum Starts (in the GUI), you are asked to enter values for a number of parameters (Table 39). The Optimum Start is preprogrammed to calculate the time necessary for the system to reach the setpoint. For example, if your optimum start is in heating mode, your setpoint is 71.6 degrees Fahrenheit, your outside temperature is 57.2 F, and your inside temperature is 62.6 F, then the optimum start forces the system into occupied mode and turns the heating phase of the system on. The period of time is calculated using data that is collected internally by the controller. Basically the controller sees how long it took the system to reach the setpoint on a daily basis. Using this information, it calculates how much time is needed for the optimum start. 65

66 Four optimum starts are in the Free Programmable Wizard. The optimum starts can be inserted into the code for use in programming using the reserved words OS1 through OS4. The Optimum Start returns a digital (ON/OFF) value. You can configure the optimum starts through the GUI. Table 39 describes the Optimum Start Configuration Window. Table 39: Optimum Start Configuration Window Field Description Mode Allows you to select from a drop-down list if the optimum start should be in heating, cooling, both, or disabled. Target Temperature Target Setpoint Outdoor Temperature Schedule Max Starting Time Description Value Figure 41: Optimum Start Configuration Dialog Box Displays a room temperature sensor input. It is compared to the Target Setpoint. You select from a pull-down menu. Displays a Data Type that you configure as the setpoint for use in the code. It is compared to the Target Temperature. You select from pull-down menu. Displays a Data Type that represents a temperature sensor input for the outside temperature. You select from a pull-down menu. Allows you to select which schedule you would like the optimum start to work with. Schedules one through four are available. Displays the maximum time that the optimum start runs for before the schedule turns to occupied mode. So if the calculated time to reach the setpoint is higher than the maximum starting time then the system takes the maximum starting time. Allows you to enter a description of the optimum start you are configuring. Allows you to enter a value for the optimum start to display. Example code: REM Here FAN is set to be equal to OS1 which is the reserved word that is used REM to represent optimum start 1. Depending on the configuration, OS1 will REM return a digital (ON/OFF) value, thus turning the FAN ON or OFF FAN = OS1 66

67 Override Definition and Sample Code Override is a built-in function and reserved word. The Override command assigns a value of 1 (ON) to the OVERRIDE reserved word for that particular input, when you press the physical button that is the manual override button. This scenario is useful when troubleshooting a system. The button causes a short circuit that is detected by the controller. If programmed into the code, the Override causes the system to turn on (if programmed in the code). The duration for which the system is on, as a result of an override, is defined as the override time. This is configurable through the Input Parameters window in the GUI. There are certain types of Inputs, which have the Override function enabled and they are: THR 10 K Type II THR 10 K Type III RTD 1 K Type 85 Every input on a controller (which is configured to one of the above allowable types) has an override capability. The override function is inserted into the code using the reserved words OVERRIDE1 through OVERRIDE12 (for 12 inputs, it would stop at OVERRIDE4 if you had only 4 inputs configured with one of the allowable sensors listed above). One of the unique features of the Free Programming Wizard is that it not only enables the override by pressing a button on the sensor, but it also disables the override if the button is pressed for more than 5 seconds. This applies to both the 10k and the 1k sensors. So for system testing purposes, this is perfect because you can turn the system on (if your override is programmed to do so in the BASIC code) with the press of a button and turn it back off by pressing it again and holding it for 5 seconds. Please see the Inputs section of this document for more details. Example code: REM Here the fan will operate when SCHEDULE1 is ON or when someone REM presses on the override button and the variable OVERRIDE1 goes to ON IF (SCHEDULE1 = ON) OR (OVERRIDE1 = ON) FAN = ON ELSE FAN = OFF ENDIF 67

68 LX-VAVCF-1 VAV Platform Flow and Damper Controller Configuration Reserved Internal Points The Free Programmable Wizard has a custom made interface when using it to configure a LX-VAVCF-1 device. This interface is represented by reserved constants and variables that are used to calibrate the device. Constants Table 40 describes the Constants. Table 40: Constants Constant Constant Number Name Constant Description 41 _MINFLOW Represents the minimum airflow requested by the controller to be in the duct. The units can be cubic feet per minute (cfm) or liter per second. 42 _MAXFLOW Represents the maximum airflow requested by the controller to be in the duct. The units can be cubic feet per minute (cfm) or liter per second. 43 _OBMAXFLOW Represents the airflow when the damper is at the fully open position. The units can be cubic feet per minute (cfm) or liter per second. 44 _KFACTOR Represents the K factor, which should be provided by the manufacturer of the metal VAV box. There is no unit for this constant as it is a factor. _ KFACTOR = ( 4005 xductarea ) PITOTFACTO R 45 _CALFACTOR Represents the corrective value for the K factor value of each VAV box. Can be entered manually or done automatically. The unit is in %. This value can be manually entered or automatically calculated by the controller. 46 _ZEROCAL Represents the value used by the controller to compensate for the inherent error in readings. The controller automatically subtracts this value from all the pressure readings that it receives. 47 _INITDAMPER Initiates the damper if the mechanical stops are moved. Initialization starts where the value reside at 1 until the initialization is stopped. 48 _DIRECTION Determines whether the motor of the actuator should rotate clockwise or counterclockwise. A value of 1 makes the motor rotate counterclockwise. A value of 0 makes it rotate clockwise. 49 _RESPFACT Represents the response factor of the control equipment. This is an exponential value. The units are in %, the recommended value is 10%. The higher the value is, the faster the reaction. 50 _NBJUMPER Unused constant. 68

69 Variable Table 41 describes the Variables. Table 41: Variables Variable Variable Name Number Variable Description 44 _DAMPER_POSITION Displays a calculation that gives a good estimate of the actual damper position. The units of this variable are in % (0-100). A value of 0% means the damper is closed and a value of 100% means the damper is fully open. 45 _DIFFPRESSURE Displays a reading of the differential pressure in the VAV box. The unit of measurement is thousands of inches of water. The differential pressure is calculated according to the following equation: Total Pressure - Static Pressure = Dynamic (Differential) Pressure 46 _FLOW Displays is a reading of the airflow in the duct. The units can be cubic feet per minute (cfm) or liter per second. 47 _FLOWSP Represents This is the flow setpoint. The units can be cubic feet per minute (cfm) or liter per second. 48 _FLOWPERCENT Represents the flow percentage that is required by the VAV and is a percentage of the range determined by Constant # 41 (_MINFLOW) and Constant # 42 (_MAXFLOW), with a 100% corresponding to _MAXFLOW and 0% corresponding to _MINFLOW and the range in between is scaled linearly. 49 _HOTAIR Indicates indicates whether the air in the duct is hot or cold. A value of 1 means that the air is warm and a value of 0 means that the air is cold. 50 _MOTORCTRLMODE Determines the mode of the VAV box. The mode/value list is: Value = 0, Mode = OFF (The controller is off) Value = 1, Mode = Open (The damper is fully open) Value = 2, Mode = Close (The damper is fully closed) Value = 3, Mode = Auto (Used for VAV, in this setting the _FLOWPERCENT value changes the _FLOWSP value which then determines the VAV's behavior automatically) Value = 4, Mode = Inlet% (Used for VVT, the _FLOWPERCENT value directly controls the action of the damper using the drive time and not the flow setpoint) Value = 5, Mode = Kfactor (This mode is used to automatically calibrate the kfactor) Value = 6, Mode = Zero Cal (This mode is used to automatically zero the pressure readings so that the displayed pressure readings are accurate.) 69

70 Methodology When the controller powers up or is reset (software), the damper opens to 100%. The variable _DAMPER_POSITION is therefore equal to 100 once the actuator reaches the open position. The following must be performed prior to zero calibration: Step 1 When DAMPER_POSITION = 100 and if the damper is closed rather than open, change the value of the constant # 48 (_DIRECTION). The damper then opens. The direction change is complete when _DAMPER_POSITION = 100. Step 2 When mechanical stops are moved, the damper must be re-initialized one time by changing the value in the constant #47 to 1. The damper moves to the open position and then moves to the closed position to calculate the new running counter. The initialization is complete when the constant _INITDAMPER reads 0. Step 3 - Zero Calibration Detach the tubes of the controller or stop the ventilation to have a reading of a null pressure differential. Enter the value 6 (zero calibration) into variable 50. Constant 46 (ZeroCal) will automatically take the calibration value. Step 4 Enter the K factor of the VAV box into constant 44. If the K factor is unknown, let it be calculated automatically by the controller when you do the calibration. (See the VAV box calibration section). Step 5 Enter the minimum and maximum flow specified for this VAV box in Constant 41 and Constant 42. Step 6 Enter the response factor of the VAV box into Constant 49 (RespFact). A factor of 100% means the dampers move to the set point position in one shot. A factor of 50% means the dampers move and then stop at 50% of the distance between its last position and the setpoint, and then it recalculates the setpoint before the next move. The default value is 10%. Step 7 - VAV Box Calibration Make the dampers open completely. (_MOTORCTRLMODE = 1) If the K factor is already entered in Constant 44: 70

71 If the flow read by the ventilation technician is not the same as the value in Variable 46 (flow), enter the value from the technician into Constant 43 (OBMaxFlow) and enter the value 5 (automatic K factor adjustment) into Variable 50 (MotorControlMode). The Constant 45 (CalFactor) is automatically corrected (in percentage). If the K factor is NOT entered in Constant 44: Enter the value read by the technician into Constant 43 (OBMaxFlow), and enter the value 5 (automatic K factor adjustment) into Variable 50 (MotorControlMode). The Constant 44 (KFactor) is automatically updated. Step 8 Enter 100% into variable 48 (FlowPercent), and enter the value 3 (automatic mode) into Variable 50 (MotorControlMode) to reach the maximum flow. The Variable 49 (HotAir) must be 0. Verify if the flow read by the ventilation technician is the same as the value in Variable 46 (flow). Enter 0% into variable 48 (FlowPercent), and enter the value 3 (automatic mode) into Variable 50 (MotorControlMode) to reach the minimum flow. Verify if the flow read by the ventilation technician is the same as the value in Variable 46 (flow). Adjust the calibration factor if needed (Constant 45). VAV Controller Automatic Mode The controller is in automatic mode if variable 50 contains the value 3. In this case, the damper will be adjusted to maintain the flow setpoint (variable 47). If a maximum flow is defined in constant 42, the flow setpoint (variable 47) is adjusted according to the flow request percentage while staying within the minimum and maximum flow specified. For example: 0% flow request gives a minimum flow if the box is in cold air mode (variable 49 is 0). By the same token, 100% flow request gives a maximum flow. If the box is in hot air mode, then variable 49 must be 1 to reverse the damper action). In this case, 0% flow request gives a maximum flow and 100% flow request gives a minimum flow. 71

72 Example Connect a temperature sensor to input #1 of the controller and configure the sensor in the Wizard. Set the input #1of the controller (CO1) to I.ROOM_SENSOR and enter a setpoint in the setpoint box. Adjust the rest of the parameters. In the code section, enter: _FLOWPERCENT = CO1 END. Enter the value 3 (automatic mode) into variable 50 (MotorControlMode). The VAV box now modulates to maintain the specified room temperature. Building Efficiency 507 E. Michigan Street, Milwaukee, WI Johnson Controls is a registered trademark of Johnson Controls, Inc. All other marks herein are the marks of their respective owners Johnson Controls, Inc. 72 Published in U.S.A.