Analog Data (AD) Object

Transcription

1 Issue Date 11/01/01 TECHICAL BULLETI Analog Data (AD) Object Introduction Page 2 Applications 2 Quick Start 3 Engineering 9 Overview of Operation 9 Input Processing 12 Alarm Limit Analysis 25 Triggers and History 35 Unreliable and Communication Status 37 Reference Tables 39 Analog Data Attribute Table 39 AD Command Table Johnson Controls, Inc. 1 Code o. LIT Software Release 12.00

2 Introduction One of the point object types Metasys software uses is an Analog Data (AD) object. Unlike most point objects, ADs are not directly associated with physical sensing hardware. Instead, the ADs treat an analog value obtained as the result of a control process, operator entry, or associated parameter (attribute) from another object, just like a hardware input. In this way, various analog values can be given the characteristics and software capabilities of an Analog Input (AI) object, including alarm analysis, change-of-state reporting, and object summaries. Applications An AD object has four major purposes and applications: Pseudo Objects--Metasys software objects contain many analog attributes, any of which can be assigned as the source, input to an AD. This allows the attribute to be treated like an object. For example, an AD object that measures air flow from a differential pressure sensor has both an unscaled value (inches of water) and a scaled value (cubic feet per minute [cfm]). An operator sees only the scaled value on standard summaries. The unscaled value attribute can be assigned to an AD object. This allows the flow sensor s pressure value to appear on summaries greatly simplifying calibration of the flow sensor. Control Process Results--Control processes can perform calculations and logical operations for facilities management. For example, a control process can calculate chiller COP or steam flow in BtuH. The results of these processes can be assigned to AD objects. This allows the user to see the calculated result in graphical and tabular summary displays, or to assign alarm limits. Duplicate Objects--It may be desirable for a single analog sensor, such as an outside temperature, to appear in many different logical system displays. This means that the sensor must have multiple names. Multiple AD objects can be created under each system name, and each assigned the value of the one real sensor. User Input--A control process may be created that requires an operator selected variable as one of its inputs. For example, a process may calculate the cost of operating a boiler, and one of its inputs is the cost of fuel. An AD object can be created as a calculation input, with a user assigned value representing fuel cost. It is even possible to have this value assigned on a time scheduled basis, as might be the case for the cost of electricity where time-of-day billing is required. 2 Analog Data (AD) Object

3 Quick Start Defining the AD This section tells you how to quickly define the AD from the Operator Workstation (OWS). Since most of the fields in the Definition window are already filled in with default values, all you need to do is fill in the fields without defaults, and make any necessary changes. The AD object can be defined: online, using the Operator Workstation AD Object Definition window. offline, using the Graphic Programming Language (GPL) Database Template. See the GPL Programmer s Manual for instructions. offline, using the Data Definition Language (DDL). See the DDL Programmer s Manual for instructions. To define an AD object online at the workstation: 1. Go to the summary of the system in which you want to add the object. 2. Select Item from the Menu bar. Then select ew from the Item menu. A dialog box for selecting the object type appears. 3. Select Analog Data from the list of object types. 4. Click OK. The AD Object Definition window appears (as shown in Figure 1). ote: An entry for Associated Inputs is not required to use the Adjust function. Analog Data (AD) Object 3

4 * System ame and C ame displayed corresponds to the path taken to get to this screen. Analog Data Definition Item Edit View Action Go To Accessory HDQTRS Head Quarters C_44 C 44 PL_44 Panel 44 System ame Object ame Expanded ID C ame C_44 OAT Outside Air Temp PL_44 Help PL_44 Comm. Disabled Graphic Symbol # Operating Instr. # 0 0 Associated Input System ame C_44 Object ame AHU Attribute ame OAT Flags Auto Dialout Enable PT History Save PT History Parameters Delay Time Initial Value Adjust Disabled Engineering Data Report Type DEG F DEG F 1 ORMAL WARIG ALARM OVERRIDE Analog Units Decimal Position High Alarm Limit Low Alarm Limit Setpoint ormalband Differential Filter Weight Messages Warning # Alarm # OE OE OE OE 0 0 AD-DEF Figure 1: AD Definition Window Displaying Default Settings ote that some of the fields are blank, and some are already filled in. You must fill in the blank attribute fields (for example, Object ame), because those fields do not have default settings. The attribute fields that are already filled in contain default settings, which you can either accept or change. Table 1 explains the attributes without default settings. The Analog Data Attribute Table section at the end of this document describes all AD object attributes. The Operator Workstation User s Manual explains the procedures for entering and changing data. 4 Analog Data (AD) Object

5 Table 1: AD Attributes without Default Values Attribute Label Description Entry Object ame Expanded ID (optional) Associated Input - System ame* Associated Input - Object ame* Associated Input - Attribute ame* Filter Weight (optional) The object name cannot already exist under the given system name. This name defines the object, such as OAT_SES (for outside air temperature sensor). ote: If you are mapping the AD to a JC/85/40 software point, the object name must contain the JC/85/40 System Type (F, S, or H), Point Type (AA, ADJ, or ACM), and the Level 3 name separated by an underscore. For example, HAA_OAT. Refer to the JC/85 Gateway Application ote (LIT ) for details. An expanded version of the object name. It appears at the Object Focus window, GPL template, and summaries, and more clearly identifies the object. For example, OUTSIDE AIR TEMP SES. The name of the system in which the associated input object resides The name of the associated input object. The object must be defined The software name of the analog attribute whose value will be read by the AD This attribute controls the action of a filter acting on the object current value. Larger settings cause the filter to smooth out differences between successive values. If you aren t using the filter, then leave the Filter Weight blank. 8 alphanumeric characters 24 alphanumeric characters 8 alphanumeric characters 8 alphanumeric characters 8 alphanumeric characters Floating Point umber blank or > 1.0 * Associated Input attributes (System ame, Object ame, and Attribute ame) are optional; however, if one attribute is defined, they must all be defined. 5. To save the new AD object, select Item from the Menu bar. Then select Save. The new AD object is added to the operational database in the etwork Controller (C). Analog Data (AD) Object 5

6 GPL Template Default attribute settings are also available in the GPL template. Figure 2 and Figure 3 show the GPL Database Template for the AD object. Analog Data Object (AD) Page 1 Identification System ame Object ame Expanded ID C ame Engineering Data Analog Units DEGF Decimal Position 1 High Alarm Limit Low Alarm Limit Setpoint ormalband Differential Filter Weight Associated Input System ame Object ame Attribute ame F10-SAVE ESC / mouse click - CACEL, PGUP/PGD - PAGE adomnu21 Figure 2: AD Default Settings at the GPL Database Template (Screen 1) Analog Data Object (AD) Page 2 Flags Auto Dialout Enable PT History Save PT History Comm Disabled Report Type ORMAL WARIG ALARM OVERRIDE OE OE OE OE Parameters Delay (min) 1 55 DEGF Messages Warning # Alarm # 0 0 Graphic Symbol # Operating Instr. # 0 0 F10-SAVE ESC / mouse click - CACEL, PGUP/PGD - PAGE adomnu22 Figure 3: AD Default Settings at the GPL Database Template (Screen 2) 6 Analog Data (AD) Object

7 Modifying and Monitoring the AD Once the AD is defined, you can modify its attributes using the AD Focus window. You also use the Focus window to monitor and command the AD. You ll find information on using Focus windows in the Operator Workstation User s Manual. You can modify the AD object: online, using the Operator Workstation AD Object Focus window offline, using Graphic Programming Language (GPL) Database Template offline, using Data Definition Language (DDL) 1 Traffic and Diagnostics Metasys Release 9.01 and later allow the mapping of the AD object to a specific parameter in every etwork Control Module (CM). These AD objects can be trended and alarmed for overall system performance monitoring once mapped. These associated input attributes do not require a system object name. Table 2 lists the reserved attribute names. Table 2: Reserved Attribute ames Attribute Description IDLE FREEMEM 1RX 1TX CM Central Processing Unit (CPU) idle time - % moving average CM available acquired memory (Kbytes) 1 messages received per minute 1 messages transmitted per minute JCBTIME JCB Interpreter - % 1RXERR IPRXERR STBYSTAT 2APPS 2ACPS 2BPPS Counter for discarded corrupted 1 ARCET messages (reset on download) Counter for 1 Ethernet messages (reset on download) Status of Standby CM 1 = responding, 2 = not responding 2 Trunk 1 Instantaneous polls/per second 2 Trunk 1 Instantaneous commands/per second 2 Trunk 2 Instantaneous polls/per second 2BCPS 2 Trunk Instantaneous commands/per second otes: 1. ot supported on etwork Port or Gateway CM types. 2. AD Focus Window shows blank for associated system/object/attributes. 3. GPL cannot define these diagnostic AD objects, but can use them in a process by uploading the CM after definition. 4. STBYSTAT attribute is available only on systems with Duty/Standby feature enabled and only on the actual Duty/Standby CM pair. Analog Data (AD) Object 7

8 This is the end of the Quick Start section. If you need more information on data entry procedures, see the Operator Workstation User s Manual and the GPL Programmer s Manual. For additional information on AD attributes, see the remainder of this document, which explains the relationship between various AD attributes from an applications perspective. In addition, you ll find an alphabetized listing of all AD attributes and commands (with descriptions and acceptable entries) at the end of this document. ote: Refer to the Control System (CS) Object Technical Bulletin (LIT ) for corresponding point mapping tables. 8 Analog Data (AD) Object

9 Engineering Overview of Operation AD software functions can be divided into three basic categories: Input Processing The AD receives input values from a number of sources. The software performs input prioritization and filtering to determine the AD current value. Alarm Limit Analysis The AD current value is compared to user defined limits to determine the object s status (normal, alarm, or warning). The status can then be routed as a Change-of-State (COS) report, and associated message, to operator devices. Triggers and History AD attribute changes can be used for other purposes including triggering control processes and historical archiving. Figure 5 is a flow diagram of AD object input processing. The blocks represent software functions. The dashed boxes represent the attributes that define or control the functions. Analog Data (AD) Object 9

10 Functional Flow Diagram Figure 4 below illustrates the general operation of an AD object. The blocks represent the functions performed by the software. The etwork Control Module (CM) performs all AD software functions. Each major block (software function) is summarized after the figure and then explained in detail throughout this document. CM Initial Value Input Prioritization Filtering Current Value Point History Alarm Limit Analysis Control Process Triggering Alarm/ Warning Delay Change-of-State Reporting ad1 Figure 4: Analog Data General Model Input Processing Initial Value You must specify an initial value for the AD when defining the object. This becomes the current value of the AD until another input value is received. Input Prioritization The Analog Data object receives its input from: - a command issued by an operator, control process, Multiple Command object, or Scheduling - an analog attribute that is sampled every 30 seconds from another object The input value is prioritized, meaning that the highest priority input becomes the AD current value. 10 Analog Data (AD) Object

11 Filtering An optional filter weight attribute may be set for the AD object during database generation. The filter weight value is used in a calculation that smoothes out erratic AD readings such as spikes and analog noise. Filtering reduces false alarms and unnecessary control process triggering resulting from input fluctuations. Current Value After input prioritization and filtering has occurred, the AD Focus window, etwork Terminal screen, and object summaries, display the Analog Data current value. Alarm Limit Analysis Alarm Limit Analysis High and low alarm limits may be defined for the AD object. If the AD current value falls outside the high or low alarm limits, an alarm is generated. In addition, a setpoint and normalband may be designated, so that the software can compute high and low warning limits. If an AD current value falls between an alarm and warning limit, a warning is issued. Other attributes, such as Differential, also play a role in alarm limit analysis. Alarm/Warning Delay This optional function delays COS reporting of the AD object for a user defined period of time. The purpose of Alarm/Warning Delay is to prevent nuisance reports. The etwork Control Module (CM) performs Alarm/Warning Delay, COS Reporting, and Triggers and History. The Alarm/Warning Delay mode is selectable on a per-cm basis via WCSetup. Select one of the following: Warning Delay mode (default): - The delay starts due to an AD setpoint change, when the AD is used as feedback for an Analog Output Setpoint (AOS) object. - Warning COS reporting is delayed, Alarm COS reporting is not delayed. - The delay time is defined in minutes (0 to 255). Alarm Delay mode: - The delay starts due to an AD setpoint change when the AD is used as feedback for an Analog Output Setpoint (AOS) object or when the AD current status changes because of a field change. The current status change starts the timer if the change is normal to warning, warning to alarm, or normal to alarm. The timer does not start if the change is alarm to warning, alarm to normal, or warning to normal. - Warning and alarm COS reporting is delayed. - The delay time is defined in minutes (0 to 255). Analog Data (AD) Object 11

12 ote: The Alarm Delay mode has no effect on an CM that uses the etwork Port or JC85 Gateway download code type. The Alarm Delay mode is not supported on CM101/102/401. Change-of-State (COS) Reporting If an alarm is detected, it may be reported at one or more Operator Workstations or printers. Operator Workstations and printers only receive the alarm report if they were defined as report destinations for the particular object during the database generation process. (Refer to the Report Router/Alarm Management Technical Bulletin [LIT ] for detailed information.) - The timer is killed if the status goes into the normal range and a COS started the timer. The timer is not killed when the timer was set by a setpoint change. Triggers and History Control Process Triggering An alarm condition and other AD attribute changes can trigger (cause) a control process to run. Point History Value of the Analog Data object may be sent to a point history file. Input Processing Initial Value Operator Override of Adjust Command Initial Value Function Attribute Control Process or MC Object Command AD Samples Attribute from Associated Input Object Scheduling Adjust Command Input Prioritization Current Value Commanded Feature Commanded Priority Adjust Disabled S/W Override Filter Weight Filtering Analog Engineering Units Current Value Current Value Alarm Limit Analysis ao2 Figure 5: AD Input Processing Functional Flow 12 Analog Data (AD) Object

13 AD Input Values Initial Value Unlike most point objects, Analog Data is not directly associated with a physical sensing device. Rather, it receives its input from a number of software sources including: an operator entered initial value an operator command, such as Override or Adjust a control process or Multiple Command (MC) object command a floating point (analog) attribute from another object a Scheduling command Each of these input sources will be discussed in detail throughout this document. This function allows you to specify an initial value attribute for the AD object. The initial value operates at Priority 3. It becomes the current value of the Analog Data object until another input is received. The initial value attribute is used if you want the AD to go online with a specific current value, such as 72 Deg F. This might be helpful in applications where several AD objects are used in a control process. For example: AD Object 1 = room setpoint value. You set the current value of this object to 72 Deg F, using the initial value attribute. AD Object 2 = discharge air temperature high setpoint value. You set the current value of this object to 120 Deg F, using the initial value attribute. AD Object 3 = discharge air temperature low setpoint value. You set the current value of this object to 55 Deg F, using the initial value attribute. The control process runs every ten minutes to reset the discharge air temperature setpoint. It does this by: 1. Comparing the room setpoint (AD Object 1) to the room temperature (AI Object). 2. Setting the discharge air temperature setpoint (Proportional plus Integral plus Derivative [PID] Loop object), so that it is between the discharge air high setpoint (AD Object 2) and discharge air low setpoint (AD Object 3) once the comparison is made. Analog Data (AD) Object 13

14 Attributes to Set for the Initial Value Function The Initial Value attribute affects the Initial Value function: Initial Value is an attribute that you specify as a numerical value such as 60.5 (for 60.5 Deg F). If you don t define an initial value, it will default to Prioritized Inputs Inputs to Analog Data objects are prioritized. This means that the highest priority input becomes the AD current value. Input Prioritization Each Analog Data object has its own object record. This record contains a priority table that serves three purposes: It lists the priority levels of all possible inputs to the AD object as shown in Table 3. It keeps track of inputs to the AD, and performs a priority check to determine which input should become the AD current value. This is shown in Table 4. It records the input that currently controls the object (that is, the input that causes the current value). Table 3: AD Input Priority Levels Priority Level Input Sources 1 Operator Entered Override Command Operator Entered Auto Command 2 Control Process or MC object Set AD Command *a Control Process or MC object Release Command 3 Operator Entered Initial Value Operator Entered Adjust Command *b Control Process or MC object Set AD Command *a*b Scheduling Adjust Command *b Sampled Attribute a* A control process or MC object Set AD command can be issued at Priority 2 or 3, depending on the level you designate in the process. b* The Priority 3 Adjust (Set AD) commands can be disabled by setting the Adjust Disabled attribute of the AD to Yes. This prevents the associated input object s value from being overwritten by the Priority 3 commands. The operator can still issue the Override command if he needs to change the AD s value manually. Table 4: Example of AD Input Prioritization Priority Level Input Sources 1 2 Control Process Set AD Command (50% RH) 3 Sampled Attribute (43.5% RH) 14 Analog Data (AD) Object

15 As you see in Table 3, three priority levels govern the AD current value. The input priority table contains three slots, one for each priority level-- Priorities 1, 2, and 3. When an input is sent to an Analog Data object, it is placed in the correct slot. In Table 4, two inputs were sent to the AD--a control process command and an attribute sample. If an input already resides in a given slot, the new input overwrites the old. For example, if another Priority 3 input (such as a scheduling command) is sent to the Analog Data object in Table 4, the Sampled Attribute value will be overwritten. This is shown in Table 5. Table 5: Example of AD Input Prioritization Priority Level Input Sources 1 2 Control Process Set AD Command (50% RH) 3 Scheduling Adjust Command (41% RH) This process is ongoing. As inputs are sent to the AD, they are immediately placed in their respective priority slots. The table can hold up to three inputs at once. The input with the highest priority at a given point in time becomes the AD current value. In Table 4, the control process Set AD command of 50% RH becomes the current value of the Analog Data, because it is the highest priority input to the object. If a control process sent a Release command to the AD, the Input Prioritization Table would look like Table 6. Table 6: Example of AD Input Prioritization Priority Level Input Sources Scheduling Adjust Command (41% RH) The Release command can only be executed from a control process or MC object command. It operates at Priority 2 and performs the function of releasing--clearing out the Set AD Priority 2 command. otice that Slot 2 doesn t have an input value: Release merely deletes whatever is contained in Slot 2. This allows the Slot 3 input to become the AD current value. In this instance, the Scheduling Adjust command of 41% RH becomes the AD current value. If you issue an Override command of 49% RH from an Operator Workstation, the AD Input Prioritization Table will look like Table 7. Override is the highest priority input to the Analog Data object, so the AD current value will change to 49% RH. Analog Data (AD) Object 15

16 Table 7: Example of AD Input Prioritization Priority Level Input Sources 1 Operator Override Command (49% RH) 2 3 Scheduling Adjust Command (41% RH) Disabling Priority 3 Commands An AD object that is mapped to an associated object s attribute receives that attribute s current value at Priority 3. Any command issued at Priority 3 (such as the operator-entered Adjust command) overwrites the value set by the associated object until the associated object s attribute is polled again (30 second poll cycle). This may be undesirable for some applications, because there are times when the current value displayed by the AD is not the same as the associated object s attribute value. For example, the operator might issue another Adjust command, possibly triggering a control process at the wrong time, based on the false information. You can prevent this by setting an attribute in the AD object that disables the Priority 3 commands. The operator can still use the Override command to manually set the value of the AD object. Attributes You Set to Disable Priority 3 Commands One attribute affects the Priority 3 commands: Adjust Disabled. Adjust Disabled specifies whether the Priority 3 commands (see Table 3 for a list of the commands) are disabled (Y) or enabled (). The default setting is (no). You can set this attribute only when you define the new AD object; it cannot be changed later. Attributes Affected by Prioritization A number of AD attributes change as a result of input prioritization. These include: Current Value 16 Analog Data (AD) Object Commanded Feature Commanded Priority S/W Override (when applicable) Current Value is updated to reflect the highest priority input value to the AD. For example, 49% RH could be displayed in this field at the AD Focus window. Commanded Feature is updated to reflect the source of the current value. Operator, Scheduling, Control Process, Initial, Multiple Cmd, or Shared is displayed in this field at the AD Focus window. (ote: Shared=Sampled Attribute).

17 Commanded Priority is updated to reflect the priority level of the Commanded Feature. The AD Focus window displays one, two, or three in this field. S/W Override is updated to Y (yes) if an operator Override command caused the new current value. The AD Focus window displays Y or (yes or no) in this field. Figure 6 shows the Focus window of an AD object whose current value resulted from a Scheduling command. Analog Data Focus Item Edit View Action Go To A ccessory BLDG-1 AHU-1 OA-T Bookmark Point History Current Trend System ame Object ame Expanded ID C ame Current Value Commanded Feature Commanded Priority AHU1 OA-T OUTSIDE AIR C5 65 DEG F SCHEDULIG 3 Reports Locked Trigger Locked Comm. Disabled Comm. Status S/W Override Status OLIE ORMAL Graphic Symbol # Operating Instr. # 0 66 Associated Input System ame Object ame Attribute ame AHU-2 OAJ VALUE Flags Auto Dialout Enable PT History Save PT History Parameters Delay Time Delay Active Initial Value Adjust Disabled 0 55 DEG F Engineering Data Analog Units Decimal Position High Alarm Limit Low Alarm Limit Setpoint ormalband Differential Filter Weight DEGF 0 Report Type ORMAL WARIG ALARM OVERRIDE Messages Warning # Alarm # OE OE OE FOLLOW-UP 0 1 ad-focon Figure 6: AD Focus Window Display Analog Data (AD) Object 17

18 Operator Commands Override Command You can command an AD to a specific current value with the Override and Adjust commands. This may be done from an Operator Workstation or etwork Terminal. Use the Auto command when you want to release the Override command allowing lower priority inputs to become the AD current value. Operator commands are executed at the following priorities: Override: Priority 1 Auto: Priority 1 Adjust: Priority 3 Use an Override command when you want total control of the AD object. This prevents other AD inputs, such as control processes and Scheduling, from changing the AD current value. You might decide to execute the Override command when: The AD gets an attribute sample from an object that s either offline or connected to defective hardware. The AD receives its input from a faulty control process. The process could be faulty if it contains incorrect logic. Another possibility is a control process that has unreliable input variables resulting from offline or defective hardware. Override Command Execution A change resulting from an override command is always executed immediately. The commanded state becomes the current value taking priority over all other AD inputs. While the Analog Data is in an overridden state, the software continues to monitor other inputs to the AD object. The inputs are placed in the priority table as they are received. These inputs do not cause change-of-state reporting or control process triggering. When the Override command is released with the Auto command, the AD object determines which of the inputs has the highest priority. This becomes the AD current value. 18 Analog Data (AD) Object

19 Operator Adjust Command Use the Adjust command when you want to set the current value of the Analog Data object at a lower priority than the Override command. This command is useful for changing the current value of an AD to trigger a control process. Unlike the Override command, it does not give you total control of the object. It is executed at Priority 3, which means it can be overwritten by other AD inputs. For example, you could use the Adjust command to change the current value of a discharge air temperature setpoint (AD object) as explained earlier. You might decide to change the value of the setpoint from 120 Deg F to 110 Deg F. ote: When the AD is mapped to a JC/85/40 ADJ point, the Adjust command is sent to the JC/85/40 system. Since the Adjust command can be overwritten by other AD inputs, you may not want to use the Adjust command if the AD has an associated input defined. The adjusted value is overwritten at the next poll of that attribute. (The Adjust command can be disabled to avoid this situation; see Disabling Priority 3 Commands earlier in this document.) If the initial value of the AD is other than one, the operator adjust command value is also stored as the Initial Value (for Release 9.0 or later). Adjust Command Execution When you issue an Adjust command, the value of this command (for example, 72 Deg F, 300 GPM, 45% RH) is sent to the AD Input Prioritization table. If your command is the highest priority input in the table, it is executed. If it is not the highest priority, the value is held in the table s Priority 3 slot. When priority Slots 1 and 2 are empty, the Adjust command is executed. Control Process Inputs Control Process Sends an Input to an AD An Analog Data object can receive an input value from a control process. Control processes can be created with Graphic Programming Language (GPL) or JC-BASIC. Typically, a control process performs some kind of mathematical calculation or logical operation with Or, And, Compare, or ot logic. The results of the control process can be sent to the Analog Data object with a Set AD or Release command. Set AD can be user defined to operate at Priority 2 or 3. You include the priority level and floating point value of the Set AD command in the control process. A floating point is a number that contains a decimal point such as A Set AD command could, for example, cause the current value of an AD to change to 70.8 Deg F. The value, 70.8 Deg F, can then be displayed or printed as an AD change-of-state report. This provides the capability of reporting the results of a control process to an Operator Workstation or printer. Analog Data (AD) Object 19

20 Application of a Control Process Input to an AD Analog Data objects can be used with control processes to calculate chiller energy usage and chiller efficiency as shown in Figure 7 and described below: CM Calculation Process 2 Calculation Process 1 DCM AI Object kw Usage AI Object Flow kw Usage Chiller AD1 AI Object CHW RET AD Object Chiller Efficiency AD Object BtuH Output AI Object CHW SUP warndel Figure 7: AD Control Process Example 1. Control Process 1 calculates chiller energy usage with the following equation: BtuH = GPM * C1 * (Return Chilled Water - Supply Chilled Water) GPM = Current Value Attribute of AI Object 1 C1 = a constant (See the Engineering Data Book for further details.) Return Chilled Water = Current Value Attribute of AI Object 2 Supply Chilled Water = Current Value Attribute of AI Object 3 2. The BtuH value is sent to the current value attribute of AD Object Control Process 2 calculates chiller efficiency using the following equation: Chiller Efficiency = kw Output Chiller kw Usage kw Output = BtuH (from Current Value Attribute of AD Object 1) * C2 C2 = a constant (See the Engineering Data Book for further details.) Chiller kw Usage = Current Value Attribute of AI Object 4 4. The chiller efficiency value is sent to the current value attribute of AD Object 2. Object summaries can then display and print this value. 20 Analog Data (AD) Object

21 Associated Input Attribute Inputs to an AD Any floating point attribute from any object (binary or analog) can be sampled by an AD object. (An attribute table is contained at the end of each technical bulletin. This table contains a listing of attribute types, including floating points). Sampling means that the AD reads the value of the floating point attribute every 30 seconds and then places this value in its input priority table. The attribute, which has a priority level of 3, becomes the AD current value if it s the highest priority input to the Analog Data object. ote: The associated input attribute is not valid if the object is mapped to a JC/85/40 software point. Attributes to Set for this Function Three attributes affect this function: System ame Object ame Attribute ame The software needs to know what analog object attribute will be sampled by the AD. You link the object attribute with the AD by setting the three attributes listed above. Once this is done and the AD object is saved, the AD automatically reads the value of the associated input at 30 second intervals. ote: If you have defined an associated input for an AD, avoid issuing other Priority 3 inputs to the object. If a Scheduling command or Priority 3 control process command were executed, it would be overwritten in 30 seconds when the next object attribute sample is taken. You can prevent this situation by disabling the Priority 3 commands (see Disabling Priority 3 Commands earlier in this document). System ame represents the System, such as AHU1, from which the object attribute sample will be taken. Enter up to eight ASCII alphanumeric characters. There is no default setting. Object ame represents the object, such as OAT_SES, from which the object attribute sample will be taken. Enter up to eight ASCII alphanumeric characters. There is no default setting. Attribute ame represents the attribute, such as current value, from which the object attribute sample will be taken. Enter the attribute name, such as Value for current value. See the Analog Data Attribute Table section at the end of this document for attribute software names. Analog Data (AD) Object 21

22 An Application of an Attribute Input to an AD An attribute sample could be used in a building application, containing two air handling units, with only one outside air temperature sensor. You might want to see the outside air temperature reading in each AHU summary. This can be achieved by creating an object that samples the current value attribute from the actual outside air temperature sensor. This sensor is defined as an Analog Input object with the name, AHU1\OAT_SES. The Analog Data object is named AHU2\OAT_SES so that you can view the sensor s status in the AHU2 system summary. Scheduling Inputs Filtering Scheduling Sends an Input to an AD Scheduling can also send an input to an AD object. Scheduling issues an Adjust command, which changes the AD current value at Priority 3. Scheduling commands are created at the Scheduling feature window, where you specify the Adjust command value, such as 68 for 68ºF (engineering units, like Deg F, aren t necessary). You also set the time when you want the command to be issued. For example, you could designate that Scheduling execute an Adjust command of 72 (Deg F) at 08:00 and an Adjust command of 68 (Deg F) at 17:00. Filtering is an optional function that smoothes out erratic input values such as spikes and analog noise. This function only applies to an AD that is sampling an attribute (such as current value) from another object. For example, an AD might be used to provide a highly filtered analog input value to a control process. The AI object from which the AD received its sample could continue to display the unfiltered input. Filtering is also helpful for reducing false alarms and unnecessary control process triggering, which could result from unfiltered inputs. Figure 8 shows how filtering affects an AD flow reading that was sampled from an AI object. 22 Analog Data (AD) Object

23 Gallons Flow in GPM Unfiltered Value Filtered Value analog4 t (Minutes) Figure 8: Filtering an AD Sampled Attribute Input Attributes to Set for Filtering The Filter Weight attribute affects filtering. Filter Weight is used in a software calculation that levels out analog input fluctuations. The larger the Filter Weight, the greater the filtering. Leave the Filter Weight blank (the default setting) if you aren t using the filter. How Does Filtering Work? The software performs this calculation: Filtered Value = Previous Filtered Value + Unfiltered Value - Previous Filtered Value Filter Weight The filtered value becomes the AD current value. Analog Data (AD) Object 23

24 Current Value The AD current value is the result of input prioritization and filtering. The current value is displayed at the AD Object Focus window and on summaries. otes: Until the AD polls the associated input value (this happens within 30 seconds of a change), the current value displayed on the AD Object Focus window and the value displayed on summaries reflect the value at the time of the last poll. Once the associated input value is polled, the current value updates to the associated object s attribute value. In the case of ADs, for up to 30 seconds, the value shown on the standard summaries may be a commanded value instead of the associated object s attribute value. This may be undesirable for some applications, so the AD provides the Adjust Disabled attribute, which can be set to Yes to disable the Priority 3 commands (see Disabling Priority 3 Commands earlier in this document). Attributes Associated with the Current Value Two attributes are associated with the current value: Current Value Analog Engineering Units Current Value is the attribute that represents the present condition of the object, such as 75.5 (for 75.5 Deg F). This attribute is not definable. Analog Engineering Units are an optional attribute which, if defined, are displayed with the current value at the AD Object Focus window, etwork Terminal (T) screen, and object summaries. Analog Units help make the current value more meaningful. For example, the AD current value can be displayed as 73.6 Deg F, 20 psi, 45% RH, 310 GPM. Deg F, psi, % RH, and GPM are Analog Units. These units can be up to six ASCII alphanumeric characters in length. 24 Analog Data (AD) Object

25 Alarm Limit Analysis Figure 9 is a flow diagram of AD alarm limit analysis. The blocks represent software functions. The dashed boxes represent the attributes that define or control the functions. Function Attribute Current Value High Alarm Limit Low Alarm Limit Setpoint Alarm Limit Analysis Status ormalband Differential Delay Time Delay Active Alarm/ Warning Delay Status Report Type ormal Report Type Warning Report Type Alarm Report Type Override Warning Message # Alarm Message # Reports Locked Auto Dial-Out Change-of-State Reporting alarm Figure 9: AD Alarm Limit Analysis Functional Flow Analog Data (AD) Object 25

26 Alarm limit analysis is a software process that compares the AD current value against user defined and software computed attribute settings. The purpose of alarm limit analysis is to determine the AD status. The status can be: ormal within the normal operating range. High or Low Warning outside the normal operating range but within warning limits. High or Low Alarm outside the alarm limits. Deg F Object in High Alarm High Alarm High Warning Object in High Warning Differential Differential Current Analog Value Object Crosses Differential, Moves from High Warning to ormal 55 Setpoint ormalband Low Warning Differential Low Alarm Differential analog1 Figure 10: AD Object Alarm Limit Analysis Graph 26 Analog Data (AD) Object

27 Attributes to Set for Alarm Limit Analysis High Alarm Limit Low Alarm Limit Setpoint ormalband Differential ote: If the object is mapped to a JC/85/40 ADJ software point, do not define the setpoint or normalband. The setpoint attribute is automatically updated when an Adjust command is issued to an AD mapped to a JC/85/40 ADJ point. High Alarm Limit If the AD reaches or goes above this limit, a high alarm COS is reported. Low Alarm Limit If the AD current value reaches or goes below this limit, a low alarm COS is reported. Setpoint This is the center point (axis) of the normal operating range for the AD current value. Setpoint is used, together with normalband, by the software to compute high and low warning limits. (The setpoint and normalband must both be defined or both blank.) ormalband This is the width of the normal operating range for the AD current value. The normalband is centered on the setpoint. ormalband is used, together with setpoint, by the software to compute high and low warning limits. (The normalband and setpoint must both be defined or both blank.) Differential This defines a buffer zone at each of the four limits. The Differential prevents excessive alarm and warning reports that could result from AD current value oscillations near any of the limits. After you define the differential, the software applies it to the high alarm limit, low alarm limit, high warning limit, and low warning limit. AD current value fluctuations within any of the differential zones do not cause a COS report. When the current value crosses over a limit and a report is issued, it must again cross over the limit and its differential before a new report is issued. IMPORTAT: Warning limit definitions must fall within alarm limits if both are used. Any floating point value (number with a decimal point) can be entered for the five attributes explained above. The values that you specify are application specific. An outside air temperature sensor will probably require different limits from a humidity or flow sensor. Analog Data (AD) Object 27

28 How Does Alarm Limit Analysis Work? Alarm limit analysis involves the following: 1. You define the previously explained attributes: High Alarm Limit, Low Alarm Limit, Setpoint, ormalband, and Differential. 2. The software uses the setpoint and normalband values to compute a High and Low Warning Limit. otes: If limits are not specified, the AD is considered a status only object. This means field changes cannot generate COS reports. Although the current value is reported to operator devices, alarm analysis is not performed. The Focus window and the summaries always show the status as normal. Always enter values or blanks for both the setpoint and normalband, or delete them both. 3. Alarm analysis begins when: The AD current value changes due to a field change or Override command. You modify one or more of the AD Warning Limits using the AD Warnings command, through an associated feedback AOS object or within a control process. You modify one or more of the AD Alarm Limits using the AD Alarms command, or within a control process. ote: An associated AOS changes the AI setpoint attribute when the AI is used as feedback for the AOS. This is explained later. 4. The CM compares the AD current value against the alarm and warning limits while also taking into account the differential. 5. A new AD object status (normal, high alarm, high warning, low warning, or low alarm) is determined based on this comparison. This new value reflects the changed Status attribute. 6. The Status: displays at the AD Focus window and T screen displays on summaries containing AD object information can cause a new COS report to appear at Operator Workstations 28 Analog Data (AD) Object

29 Application Example of Alarm Limit Analysis If you were setting alarm limit analysis attributes for a discharge air temperature sensor, you might specify the following: High Alarm Limit [65] Deg F Low Alarm Limit [40] Deg F Setpoint [55] Deg F ormalband [10] Deg F Differential [ 2] Deg F The alarm limit analysis graph for this sensor would look like Figure 10, shown earlier. The graph in Figure 10 is derived from the software calculations shown in Table 8. High and Low Warning Limits are computed, using the setpoint of 55 Deg F and normalband of 10 Deg F. The Differential of 2 Deg F is applied to each limit as follows: Table 8: Software Calculation of Limits and Differentials Limit/Differential Software Calculation High Warning Limit Low Warning Limit High Warning Limit Differential Low Warning Limit Differential High Alarm Limit Differential Low Alarm Limit Differential = 60 Deg F = Setpoint + 1/2 ormalband = 50 Deg F = Setpoint - 1/2 ormalband = 58 Deg F = High Warning Limit - Differential = 52 Deg F = Low Warning Limit + Differential = 63 Deg F = High Alarm Limit - Differential = 42 Deg F = Low Alarm Limit + Differential Based on the graph in Figure 10, COS reports would be issued as described in Table 9. Table 9: Description of Alarm Limit Analysis Condition Alarm Limit Analysis of Figure 10 High Alarm High Warning Low Warning Low Alarm Differential If the AD current value > 65 Deg F, a high alarm report is generated. If the AD current value > 60 Deg F, a high warning report is generated. If the AD current value < 50 Deg F, a low warning report is generated. If the AD current value < 40 Deg F, a low alarm report is generated. If the AD current value fluctuates within any differential range, no new report is generated. However, if it crosses over a differential line, a new report is generated. For example, if the AD current value changed from 65 Deg F (high alarm) to 64 Deg F, no new report would be issued. When it changed to 63 Deg F (the differential line), a high warning report would be issued. Analog Data (AD) Object 29

30 Alarm/Warning Delay This function can be selected to delay warning or alarm COS reporting of the AD object for a user defined period of time. The purpose of Alarm/Warning Delay is to prevent nuisance reports. The Alarm/Warning Delay mode is selectable on a per CM basis via WCSetup. Select one of the following: Warning Delay mode (default) Alarm Delay mode 30 Analog Data (AD) Object Attributes to Set for Alarm/Warning Delay The two attributes affecting alarm/warning delay are Delay Time and Delay Active. Delay Time has two modes. Delay Time (specifies the time that the software waits before issuing a COS report). This value is the same for both warning and alarm. Warning Delay mode (default): - The delay time starts when the AOS object sends a new setpoint value to the AD object. - Warning COS reporting is delayed; Alarm COS reporting is not delayed. - The delay time is defined in minutes (0 to 255) with 0 representing no delay. Alarm Delay mode: - The delay timer starts when the AOS object sends a new setpoint value to the AD object or when the AD current state changes because of a field change. The current state change starts the timer if the change is normal to warning, warning to alarm, or normal to alarm. The timer does not start if the change is alarm to warning, alarm to normal, or warning to normal. - Warning and alarm COS reporting is delayed. - The delay item is defined in minutes (0 to 255) with 0 representing no delay. otes: If you are mapping the AD to a JC/85/40 AA or ACM software point, the Delay Time must equal zero. If you are mapping the AD to a JC/85/40 ADJ software point, the Delay Time must equal a value other than zero. (The JC/85/40 will use the AD s Delay Time value as the ADJ feedback timer.) The Alarm Delay mode has no effect on an CM that uses the etwork Port or JC85 Gateway download code type. Delay Active indicates whether the delay function is currently active or not. Y indicates that it is active; indicates that it is not active.

31 Application Example of Warning Delay Figure 11 shows an AD object used as feedback for an AOS object. This application involves two chillers with a common supply side and one temperature sensor. An AI object defines the temperature sensor. An AD object was created to sample the current value attribute of the AI object. This allows the temperature reading to be reported for both chillers. AD AD Object Chiller 1 AOS Object O S M CV SP DA PI Control Panel Chiller 2 adproces Figure 11: Application of AD Warning Delay In Figure 11, there are two separate objects: an AOS object (used to adjust the chiller setpoint) and an AD object (used to provide feedback on chiller discharge temperature). This is how it works: 1. When the AOS is defined, Feedback attributes are specified. These attributes designate the AD object (associated with an AI object) as feedback for the AOS. 2. The AOS sends a setpoint value to the chiller controller. When this command is issued, the AOS also sends a new setpoint value to the AD. The AD setpoint had been 47 Deg F. The AOS now changes it to 43 Deg F (that is, it s expected that the discharge temperature sensor will detect 43 Deg F after the chiller controller stabilizes). 3. When the AOS sends out the new AD setpoint value, the AD warning delay timer starts. If the timer weren t started, the AD would immediately go into high warning. 4. After the warning delay times out five minutes, for example the current value of the AD is read by the software. Analog Data (AD) Object 31

32 5. If the current value is between the high and low warning limits, the AD status is considered normal. If the current value is outside these limits, the AD is in a warning state. Alarm/Warning Delay Process with an CM When initializing an CM to use the new Alarm Delay feature, the Warning Delay feature operation changes. Regardless of whether the setpoint has changed, warning reporting is delayed. Figure 12 shows how the Alarm/Warning Delay works, when the General Alarm Delay flag is set for an CM. The Alarm/Warning delay process begins when the object changes state (A), the setpoint changes (B), or the delay timer expires (C). A Object changes state B Is the Delay Timer running? Yes Is the new state ormal? Yes How was the timer started? Setpoint Changes o Object state changes from: ormal to Warning or Warning to Alarm or ormal to Alarm o End Setpoint Change COS Start or restart the Delay Timer (whether it is currently running or not) minutes (A value of 0 means reports are not delayed) Yes o What timer value is configured for this object? 0 > 0 Start the Delay Timer (1-255 minutes) Kill the Delay Timer (Set it to 0) Issue Report* (with current value) End C Delay Timer expires Issue Report* (with current value) End *Issue a report if the state of the object is different than the last reported state and if the object is configured to send reports for the current state. alarm delay.vsd Figure 12: Alarm/Warning Delay Process 32 Analog Data (AD) Object

33 COS Reporting A detailed explanation of Change-of-State (COS) reporting is contained in the Report Router/Alarm Management Technical Bulletin (LIT ). A brief discussion of this topic follows. When the status (alarm, warning, normal, or override) of an AD object changes, a COS report can be sent to one or more devices, including an Operator Workstation, CM printer, and Workstation printer. Destinations are defined using the Report/Access Group - Add Destination dialog box access from the Report Access Group Focus window. Refer to Defining Report/Access Groups chapter in the Operator Workstation User s Manual for details. Attributes to Set for COS Reporting Eight attributes affect COS reporting: Report Type ormal Report Type Warning Report Type Alarm Report Type Override Warning Message # Alarm Message # Reports Locked Auto Dial-out Report Type ormal represents the COS report that is generated when the AD s status changes to normal. Acceptable entries for this attribute and the other report types are explained below. Report Type Warning represents the COS report that is generated when the AD s status changes to high or low warning. Report Type Alarm represents the COS report that is generated when the AD s status changes to high or low alarm. Report Type Override represents the COS report that is generated when you ve set the AD current value with the Override command. Analog Data (AD) Object 33