LEARNING ACTIVITY PACKET MECHATRONICS PLC TIMER INSTRUCTIONS (SIEMENS S7-300/STEP 7) B25014-AA04UEN

Transcription

1 MECHATRONICS LEARNING ACTIVITY PACKET PLC TIMER INSTRUCTIONS (SIEMENS S7-300/STEP 7) B25014-AA04UEN

2 LEARNING ACTIVITY PACKET 4 PLC TIMER INSTRUCTIONS INTRODUCTION This LAP discusses PLC Timer instructions and their applications. Timer instructions are used extensively in PLC programs to provide time-based logic and sequencing for the controller. PLC s support several types of timer instructions with each operating slightly differently. A thorough understanding of the operation of the timer instructions is necessary for anybody who must troubleshoot PLC programs or PLC-controlled machines. ITEMS NEEDED Amatrol Supplied PS7313-AAU, 870-PS7314-AAU, or 870-PS7315-AAU Mechatronics Learning System-S IOSS7-AAX I/O Simulator Learning System 1 87-MS1 Pick and Place Feeding Station or 1 87-MS2 Gauging Station or 1 87-MS3 Orientation-Processing Station or 1 87-MS4 Sorting-Buffering Station or 1 87-MS5 Servo Robotic Assembly Station or 1 87-MS6 Torque Assembly Station or 1 87-MS7 Inventory Storage Station Amatrol or School Supplied Step 7 Programming Software PC Programming Interface for Siemens S7 PLCs School Supplied 1 Computer 1 Printer FIRST EDITION, LAP 4, REV. C Amatrol, AMNET, CIMSOFT, MCL, MINI-CIM, IST, ITC, VEST, and Technovate are trademarks or registered trademarks of Amatrol, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies. Copyright 2012, 2011 by AMATROL, INC. All rights Reserved. No part of this publication may be reproduced, translated, or transmitted in any form or by any means, electronic, optical, mechanical, or magnetic, including but not limited to photographing, photocopying, recording or any information storage and retrieval system, without written permission of the copyright owner. Amatrol,Inc., 2400 Centennial Blvd., Jeffersonville, IN USA, Ph , FAX

3 TABLE OF CONTENTS SEGMENT 1 TIMER INSTRUCTION BASICS OBJECTIVE 1 Describe the function of two types of Siemens timer instructions OBJECTIVE 2 Describe three categories of timer instructions available in a Siemens STEP 7 project OBJECTIVE 3 Describe the operation of the on-delay timer coil instruction SKILL 1 Enter and edit a PLC program that uses an on-delay timer coil instruction OBJECTIVE 4 Describe the operation of the off-delay timer coil instruction SKILL 2 Enter and run a PLC program that uses an off-delay timer coil instruction SEGMENT 2 RETENTIVE ON-DELAY TIMER COIL INSTRUCTIONS OBJECTIVE 5 Describe the operation of the retentive on-delay timer coil instruction SKILL 3 Enter and run a PLC program that uses a retentive on-delay timer coil instruction SEGMENT 3 PULSE TIMER COIL INSTRUCTIONS OBJECTIVE 6 Describe the operation of the pulse timer coil instruction SKILL 4 Enter and run a PLC program that uses a pulse timer coil instruction OBJECTIVE 7 Describe the operation of the extended pulse timer coil instruction SKILL 5 Enter and run a PLC program that uses an extended pulse timer coil instruction SEGMENT 4 TIME DRIVEN SEQUENCING OBJECTIVE 8 Defi ne time-driven sequencing and give three applications OBJECTIVE 9 Describe the operation of a time-driven sequence program Activity 1 Operation of a time-driven sequence program SKILL 6 Design a PLC program that provides low-voltage starting of an electric motor SKILL 7 Design a PLC program that uses a time-driven sequence to control an actuator 3

4 SEGMENT 1 TIMER INSTRUCTION BASICS OBJECTIVE 1 DESCRIBE THE FUNCTION OF TWO TYPES OF SIEMENS TIMER INSTRUCTIONS PLC timer instructions are designed to perform the same functions as the hardwired timers they replace: they provide control logic by opening and/or closing their contacts after a predetermined amount of time passes. Timer instructions are often used in machine controls to provide a time delay between two events in a machine s sequence of events. Typical applications include reduced voltage starting, plastics injection molding, as shown in figure 1, and general purpose machine sequencing. Figure 1. Plastics Injection Molding Machine. Photo Courtesy of Cincinnati Milacron 4

5 One way to classify PLC timer instructions is according to the way the instruction is reset. Two classifications of PLC timers are retentive and non-retentive timers. These are described as follows: Retentive Timers A retentive timer accumulates (records) the total amount of time the instruction has been energized and retains this value even when it is de-energized. The timer will resume timing from the retained value the next time it is energized. A retentive timer instruction must be reset by a separate reset instruction before it can operate again. Retentive timers are often used in pumping applications to indicate the total amount of material that has been pumped into a container. If the pump stops during the middle of the fill operation, it can be restarted and complete its task because the timer retains its value. Non-Retentive Timers A non-retentive timer, like the retentive timer, accumulates time, when energized. It resets whenever the input is de-energized. Because the non-retentive timer instruction resets when de-energized, it does not use a separate reset instruction. Non-retentive timers are often used in applications involving machinery startups, where the timer should start from the beginning again if its timer cycle is stopped before it times out. 5

6 OBJECTIVE 2 DESCRIBE THREE CATEGORIES OF TIMER INSTRUCTIONS AVAILABLE IN A SIEMENS STEP 7 PROJECT There are three categories of timer instructions available in a Siemens STEP 7 project. The three categories are: STEP 5 Block Format Timers STEP 5 Coil Format Timers STEP 7 System Function Block Timers STEP 5 Block Format Timers Figure 2 shows the Timers folder in the LAD/STL/FBD Program Editor s Program Elements window. STEP 5 BLOCK FORMAT TIMERS STEP 5 COIL FORMAT TIMERS Figure 2. STEP 5 Timers 6

7 All of the timers contained in this folder are STEP 5 timers. The timers are included in the STEP 7 software to make it easier to convert STEP 5 projects to STEP 7, and for programmers who are familiar with STEP 5 instructions. The first five timers in the folder are the STEP 5 Block format timers. Block format timer instructions have the inputs and outputs inserted around a rectangular instruction block. Figure 3 shows a STEP 5 block format timer instruction. Network 1: Title: T0 I0.1 S_ODT S Q TIMER NUMBER Q4.0 S5T#10S TV BI Mw0 I0.1 R BCD Mw2 PRESET TIME VALUE Figure 3. Block Format Timer instruction STEP 5 Coil Format Timers The second set of timer instructions shown in figure 2 are coil format timer instructions. The coil format timer instructions are displayed on the right side of a network as output coils. The timer number and preset time value are inserted above and below the coil. Figure 4 shows a STEP 5 coil format timer instruction. Ob1: Main Program Sweep (Cycle) Network 1: Title: TIMER NUMBER I0.1 T0 SP PRESET TIME S5T#10S VALUE Figure 4. Coil Format Timer Instruction 7

8 STEP 7 System Function Block Timers The Standard Library in the Libraries folder in the Program Elements window contains a folder named System Function Blocks (SFBs), shown in figure 5. This folder contains STEP 7 SFB instructions. STEP 7 SYSTEM FUNCTION BLOCK TIMERS Figure 5. STEP 7 System Function Block Timers SFB instructions are a part of the processor s operating system. This means that if an SFB timer instruction is used, it requires less processor memory than a STEP 5 timer does. If a STEP 5 timer is used, the instruction and the data associated with the instruction are downloaded to the processor. If an SFB timer instruction is used, only the data associated with the timer is downloaded to the processor. The SFB instructions, including the timer instructions, are STEP 7 instructions that are IEC compliant. IEC compliant means that the instructions conform to IEC Standard , which is the international standard for PLC programming languages. It defines how instructions are to appear and operate for several PLC programming languages. The STEP 7 versions of these languages are Ladder Logic, Statement List, Functional Block Diagram, S7-Graph, and SCL (Structured Control Language). One of the benefits of languages that follow the standard is that it allows multiple languages to be used in the same PLC and in the different blocks of a PLC project. This allows a programmer to select the best language for a particular task. This is why a larger STEP 7 project will contain blocks that have been programmed using different languages. 8

9 OBJECTIVE 3 DESCRIBE THE OPERATION OF THE ON-DELAY TIMER COIL INSTRUCTION An On-Delay Timer Coil instruction energizes its contacts after it has been turned on for an amount of time equal to its preset value. Its contact will remain on until the Timer Coil is de-energized, resetting the timer. If the On-Delay Timer Coil instruction is de-energized before it times out, the time value is reset to the preset value, and the contacts are not energized. The Siemens On-Delay Timer Coil instruction is shown in figure 6. TO SD S5T#10S Figure 6. On-Delay Timer Coil Instruction The On-Delay Timer Coil instruction is often used in applications involving the starting sequence of several large motors. In these applications, the On-Delay Timer instructions are used to stagger the starting time of each motor to reduce peak power consumption and the company s utility bill. An On-Delay Timer Coil can also be used to allow an oven to reach temperature before starting production. 9

10 The components of the On-Delay Timer Coil instruction are shown in figure 7 and described as follows: OB1: TITLE: NETWORK 1: TITLE: I0.0 T0 SD S5T#10S TIMER NUMBER ON-DELAY TIMER COIL (SD) PRESET TIME VALUE (TIME VALUE) NETWORK 2: TITLE: T0 Q4.0 TIMER CONTACTS NETWORK 3: TITLE: T0 Q4.1 Figure 7. On-Delay Timer Coil Instructions and Components Timer Coil (SD) - The Timer coil causes the timer to start timing whenever it is turned on by the network logic. Timer Number - Each timer instruction uses a number to identify the timer instruction. This timer number corresponds to a memory location in the PLC. This timer location is used to store status information about the timer. Timer Contacts - The timer uses associated contacts, just like coil relays. These contacts can be either N.O. or N.C. They are identified as timer contacts by using the same address as the timer coil. 10

11 Preset Time Value - With the On-Delay Timer Coil Instruction (SD), the Preset Value represents the timer s Time Delay. Or put another way, the amount of time that the instruction must be energized before the timer coil is energized. The Siemens (SD) instruction may be programmed for time resolutions of 10, 1.0, 0.1 and 0.01 seconds. The instruction s Preset Value can be manually entered using the following format: S5T#_xh_ym_zs_xxms (user variables are x, y, z, xx,) Where units are: h (hours), m (minutes), s (secs), ms (milliseconds). Three examples of preset values entered using this format and the resulting time delay are given in the table below. The maximum time value is 9,900 seconds, or 2H_46M_30S. EXAMPLE S5T#4S S5T#2h_15m S5T#1H_12M_18S Figure 8. Delay Times RESULTING TIMER DELAY 4 seconds 2 hours and 15 minutes 1 hour, 12 minutes, and 18 seconds Memory words can also be used to define the timer s Preset Value. This means the Preset Value is variable. A program can be designed to change the Preset Value based on program logic. If a memory word is used, it must be in the following format: W#16#abcd Where a is the time base and bcd is the time value in BCD format. The time base value and time value ranges are listed in the following table. VALUE TIME BASE TIME VALUE RANGE 0 10 ms 10 ms to 9.99 s ms 100 ms to 99.9 s 2 1 s 1 s to 999 s 3 10 s 10 s to 9990 s Figure 9. BCD Time Values For example, W#16#2001 is used for a time value of 1 second. W#16#1001 is used for a time of 100 ms. 11

12 To understand how the On-Delay Timer instruction works, lets examine the example of figure 10. A PLC program with an On-Delay Timer Coil is shown in its initial condition. Since N.O. Contact instruction I0.0 is open, the timer coil is not energized and the timer is not running. Output Coil, however, is on because N.C. Contact instruction T0 is closed (again, the timer coil is not energized). Because the timer is not running, its timer value is zero seconds. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 PRESET TIME VALUE Figure 10. Initial Condition of On-Delay Timer Program 12

13 In figure 11, PB1 is pressed, causing N.O. Contact instruction I0.0 of Network to close. There is now logical continuity to the On-Delay Timer Coil instruction T0, and the timer starts timing. The timer begins at the Preset Time Value and decreases. The relay contacts labeled T0 on Networks 1 and 2 remain in their de-energized or normal state because the Timer Value has not yet reached zero. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE = 0 I0.0 L1 L2 Figure 11. Timer Coil Energized, Timer Now Timing 13

14 In figure 12, the Timer Value has elapsed and the timer s contacts are switched to their energized state. N.O. Contact instruction T0 of Network 2 closes and N.C. Contact instruction T0 of Network 3 opens. As a result, Output Coil turns on and turns off. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE = 0 I0.0 L1 L2 Figure 12. Timer Value Reaches 0 14

15 In figure 13, PB1 is released and N.O. Contact instruction I0.0 opens. This turns off timer T0. Because of this, the contacts addressed T0 (N.O. and N.C.) are de-energized, and the Output Coils of Networks 2 and 3 turn off and on respectively. The program is now in its initial condition. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 13. Timer Instruction De-energized (and Reset), Output Coils and Turn Off and On Respectively 15

16 In figure 14, PB1 is again actuated. As a result, N.O. Contact instruction I0.0 once again energizes the On-Delay Timer Coil instruction T0, and the timer starts timing. The timer begins from the Preset Value and begins decreasing. The relay contacts labeled T0 on Networks 1 and 2 remain in their de-energized or normal state because the timer has not yet reached zero. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 14. Timer Coil Energized, Timer Now Timing 16

17 In figure 15, PB1 is released before the timer times out. As a result, the Timer Coil is reset. The timer contacts never energized because the instruction was reset before the Timer Value reached zero. The On-Delay Timer instruction returns to its initial condition. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 15. PB1 Released, Timer Resets to Zero 17

18 SKILL 1 ENTER AND EDIT A PLC PROGRAM THAT USES AN ON-DELAY TIMER COIL INSTRUCTION Procedure Overview In this procedure, you will enter and run a PLC Program that uses an On- Delay Timer Coil Instruction (SD). This will teach you how the instruction works and how to enter the instruction. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 3. Start up the SIMATIC Manager. 4. Create a new PLC project named L4S1xxx where xxx represents your initials. The SIMATIC Manager should appear on the screen with only the L4S1 project object present. In the next step, the Station object will be uploaded from the processor. The Upload will contain all of the hardware configuration, blocks, and data that are currently in the processor. 18

19 5. Perform the following substeps to upload the Station object from the processor. A. Select Upload Station from the PLC menu as shown in figure 16 (Upload Station to PG... if using STEP 7 Version 5.3 and higher). PLC MENU UPLOAD STATION Figure 16. Selecting Upload from the PLC Menu The Select Node Address dialog shown in figure 17 should appear on the monitor. The dialog displays all of the active nodes connected to the PC. Figure 17. Select Node Address Dialog 19

20 B. Click the View button on the dialog to display a list of active nodes on the MPI network as shown in figure 18. The dialog should show an entry for MPI address 2. CONNECTED STATION Figure 18. Displaying the MPI Nodes C. Select the entry in the Enter Connection to Target Station window so that it is highlighted as shown in figure 18. D. Click OK on the dialog to begin uploading the configuration to the PC. An Upload to PG dialog similar to the one shown in figure 19 should appear as the configuration is uploaded. Figure 19. Upload to PG Dialog 20

21 Your screen should appear as shown in figure 20 after the upload has completed. VIEW MENU INSERTED STATION OBJECT Figure 20. Uploaded Station E. Fully expand the project tree by selecting Expand All from the View menu. The option is Expand All if using STEP 7 Version 5.2 or Show All Levels if using STEP 7 Version 5.3 and higher. F. Click the Blocks folder to select it and display the OB1 object in the righthand project window. This OB1 Block is the Block that was last downloaded to the processor. G. Right-click on the OB1 block and select Delete from the shortcut menu. A dialog should appear to warn that the action cannot be undone. H. Click Yes on the dialog to delete the OB1 block. The block should be removed from the right-hand project window. 21

22 I. Right-click on the Blocks folder and select Insert New Object > Organizational Block from the shortcut menu as shown in figure 21. SHORTCUT MENU Figure 21. Inserting OB1 The Properties - Organizational Block dialog shown in figure 22 should appear. Figure 22. Properties - Organizational Block Dialog 22

23 J. Make sure that OB1 is listed in the Name field and that LAD is selected as the programming language. K. Click OK on the dialog to create OB1. OB1 should now appear in the right-hand side project window. This is one way to start a new project without having to manually configure the hardware. Another way to start with an empty OB1 block is to open OB1 and delete the contents. 6. Perform the following substeps to open Organization Block OB1. A. Expand the SIMATIC Manager s project tree and select the Blocks folder so that Organization Block OB1 is displayed, as shown in figure 23. Figure 23. Organization Block OB1 Displayed by SIMATIC Manager 23

24 B. Double-click Organization Block OB1 to open the LAD/STL/FBD Editor, as shown in figure 24. C. Click the Overviews on/off button to open the Overviews window if it is not currently open. D. Click the Program Elements button to display the Program Elements in the Overview window if it is not already selected. OVERVIEWS ON/OFF BUTTON OVERVIEWS WINDOW PROGRAM ELEMENTS BUTTON Figure 24. Organizational Block OB1 24

25 7. Examine the program shown in figure 25. This program is similar to that discussed in the previous objective. In the next few steps, you will enter this program into Organizational Block OB1. OB1: TITLE: NETWORK 1: TITLE: I0.0 T0 SD S5T#10S NETWORK 2: TITLE: T0 Q4.0 NETWORK 3: TITLE: T0 Q4.1 Figure 25. PLC Program Containing On-Delay Timer Coil 8. Click Network 1 to select it for editing. The Network should highlight. 9. Use the LAD/STL/FBD Editor to enter the N.O. Contact instruction I0.0 as shown in figure Perform the following substeps to enter the On-Delay Timer Coil instruction (SD), shown in figure 25. A. Make sure the Program Elements Window is visible on your monitor, as shown in figure 24. The Program Elements Window provides a list of Ladder elements or instructions. 25

26 B. Use the Program Elements Window s vertical scrollbar to display the Timers folder, as shown in figure 26. VERTICAL SCROLLBAR Figure 26. Timer Folder Displayed in Program Elements Folder C. Double-click the Timers folder (or click the plus sign [+] to the left of the Timers Folder) to open the folder. A listing of available timer instructions will be displayed in the Program Elements Window, as shown in figure 27. STEP 5 BLOCK FORMAT TIMERS STEP 5 COIL FORMAT TIMERS PULSE TIMER COILS DELAY TIMER COILS Figure 27. Timers Folder Expanded 26

27 D. Double-click the On-Delay Coil instruction (SD) to select and insert the instruction into Network 1 of OB1. The On-Delay Coil instruction (SD) appears at the end of Network 1, its Timer Number and Time Value fields containing question marks. E. Click the Timer Number field on top of the coil to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter a Timer Number of T0. T0 is entered as the timer number, as the Timer Value field appears selected for editing (boxed). T0 defines the memory area used for this particular timer. This means that status information regarding this timer will be stored in PLC memory area T (dedicated to timer instructions) word 0. G. Type S5T#10S and then press Enter to enter the timer s Preset Value. S5T#10S is the format for explicitly defining the Preset Value for the Timer. This will cause the timer to delay for 10 s (or seconds) before energizing its contacts. The format you should recall is: S5T#_xh_ym_zs_xxms (user variables are x, y, z, xx,) Where available units are: h (hours), m (minutes), s (secs), ms (milliseconds) Congratulations, you have just entered an On-Delay Timer Coil Instruction! 11. Click the New Network button (located in the LAD/STL/FBD Editor s toolbar) to insert Network 2 into the logic of OB1. Network 2 should appear on your monitor. 12. Click the newly created Network to select it for editing. 13. Perform the following substeps to place a timer contact on the newly created network. A. Click the N.O. Contact button (located on the LAD/STL/FBD Editor s toolbar) to insert the N.O. Contact instruction on Network 2. A N.O. Contact instruction appears on the rung, question marks in place of its address. B. Type T0 and then press Enter to enter the address as that of the On-Delay Timer Coil instruction of Network 1. This contact is now associated with the timer instruction of Network 1. This means that when the On-Delay Timer Coil times out, the contact will energize. C. Enter the remaining network logic of OB1, as shown in figure Save your PLC project. 15. Perform a memory reset on the processor. 16. Download the SIMATIC 300 Station object to the PLC. 17. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 18. Go online with the processor and monitor the OB1 block. 27

28 19. Perform the following substeps to test your new PLC Program. A. Examine the PLC program on your computer monitor. You should observe that On-Delay Timer (SD) Coil T0 is de-energized as are both of its contacts with the same address (on Networks 2 and 3). N.O. Contact instruction T0 is open and N.C. Contact instruction T0 is closed. Because of this, only output Q4.1 is on. B. Turn switch 1 on. This causes the N.O. Contact instruction I0.0 of Network 1 to energize and turn on the timer instruction. Notice that the coil is not yet energized. The timer contacts labeled T0 remain in their de-energized state because the Timer Value has not yet reached zero. You should also notice that the timer displays the time remaining before it will energize its contacts. In ten seconds, the timer times out. On the monitor, the coil is energized as are the contacts associated with it. N.O. Contact instruction T0 closes energizing Output Coil Q4.0 (as well as lamp 1). At the same time N.C. Contact instruction T0 opens de-energizing Output Coil Q4.1. (as well as lamp 2). The On-Delay Timer Coil, the associated timer contacts, and their outputs will remain like this as long as the On-Delay Timer Coil remains energized. C. After the timer has timed out, turn switch 1 off. The On-Delay Timer Coil instruction is de-energized and reset as are its associated contacts. As a result, N.O. Contact instruction T0 opens turning off Output Coil instruction Q4.0 (lamp 1). At the same time, N.C. Contact instruction T0 closes and turns on Output Coil instruction Q4.1 (lamp 2). D. Turn switch 1 on. Again this causes N.O. Contact instruction I0.0 of Network 1 to energize and turn on the timer instruction. Notice that the coil is not yet energized. The timer contacts labeled T0 remain in their de-energized state because the timer value has not yet reached its Preset Value. You should also notice that the timer displays the time remaining before it will energize its contacts. E. Turn switch 1 off before the timer times out. You should notice that the On-Delay Timer is turned off and is reset before its contacts are energized. Output Coil Q4.0 remains off because N.O. Contacts T0 were never closed. Output Coil Q4.1, on the other hand, remains on because N.C. Contacts T0 were never opened. 28

29 20. Repeat Step 19 several times to become more familiar with the operation of the timer instruction. 21. Click the Monitor button to go offline from the processor. 22. Perform the following substeps to change the timer value associated with T0. A. Click on the text S5T#10S below timer T0 as shown in figure 28. The timer should appear selected, or highlighted in green and the timer value should appear in a box with the timer value highlighted in blue. Figure 28. Selecting Timer T0 s Time Value 29

30 B. Type the text S5T#5s to change the timer value from 10 seconds to 5 seconds. As you begin to type a drop-down list should open on the screen as shown in figure 29. Figure 29. Entering the Timer Value C. Press Enter. The drop-down list should disappear, and the new timer value should appear under the timer in a box with the text selected or highlighted in blue, as shown in figure 30. Figure 30. Timer Value Selected 30

31 D. Press Enter again. The timer value should appear under the timer as shown in figure 31. The timer should appear selected, or highlighted in green. Figure 31. Timer Value Entered 23. Perform the following substeps to test the timer with the new timer value. A. Click the Download button to download OB1 to the processor. B. Click the Monitor button to go online with the processor. C. Turn switch 1 on. The timer should begin counting down from 5 seconds. When 5 seconds have elapsed, the timer should stop counting and Output Coil Q4.0 should energize. D. Turn switch 1 off. E. Click the Monitor button to go offline from the processor. 24. Use the PLC programming software to place the PLC into STOP mode. 25. Close the LAD/STL/FBD Editor. 26. Close the SIMATIC Manager. 27. Perform the following substeps to power down the trainer. A. Turn off the PC and monitor. B. Turn off the PLC trainer. 31

32 OBJECTIVE 4 DESCRIBE THE OPERATION OF THE OFF-DELAY TIMER COIL INSTRUCTION An Off-Delay Timer Coil instruction energizes its contacts as soon as the instruction is energized. When the timer coil is de-energized, the contacts remain energized and the timer starts timing. When the preset time value has elapsed, the timer de-energizes its contacts. If the Off-Delay Timer Coil instruction is re-energized before the preset time value has elapsed, the contacts remain on, but the time value is reset to the preset time value. The Siemens Off-Delay Timer Coil instruction is shown in figure 32. TO SF S5T#10S Figure 32. Off-Delay Timer Coil Instruction The Off-Delay Timer Coil instruction is often used in applications such as the shutdown of a chemical process that uses a series of pumps. The instructions are used to shut down the pumps in an orderly manner to ensure proper startup later and to prevent possible unsafe conditions. Another application is to keep cooling fans on a certain amount of time after a furnace has been turned off. 32

33 The components of the Off-Delay Timer Coil instruction are shown in figure 33 and are described as follows: TIMER NUMBER OFF-DELAY TIMER COIL (SF) PRESET TIME VALUE TIMER CONTACTS Figure 33. Off-Delay Timer Coil Instruction and Components Timer Coil (SF) - The Timer Coil causes the timer to start timing whenever it is turned on by the network logic. Timer Number - Each timer instruction uses a number to identify the timer instruction. This timer number corresponds to a memory location in the PLC. This timer location is used to store status information about the timer. Timer Contacts - The timer uses associated contacts, just like coil relays. These contacts can be either N.O. or N.C. They are identified as timer contacts by using the same address as the timer coil. Preset Time Value - With the Off-Delay Timer Coil Instruction (SF), the Preset Value represents the timers Time Delay. This is the amount of time that the contacts stay on after the coil is de-energized. The format is identical to the format for the On-Delay Timer Coil. 33

34 To understand how the Off-Delay Timer Instruction works, examine the following example. Figure 34 shows the initial condition of a PLC program that uses an Off-Delay Timer instruction. Since N.O. Contact instruction I0.0 is open, the timer coil is not energized and the timer is not running. Output Coil is on because N.C. Contact instruction T0 is closed. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 PRESET TIME VALUE Figure 34. Initial Condition of Off-Delay Timer Program 34

35 In figure 35, PB1 is pressed causing N.O. Contact instruction I0.0 of Network 1 to close. There is now logical continuity to the Off-Delay Timer Coil instruction T0 (the timer is energized). The Off-Delay Timer Coil energizes its contacts immediately, N.O. Contact instruction T0 closes turning on Lamp L1 and N.C. Contact instruction T0 opens turning off Lamp L2. The timer, however, doesn t begin timing. This is because the coil is an Off-Delay Timer Coil, meaning that the timing condition is delayed until the input is turned off. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 35. Off-Delay Timer Coil Energized, Contact Energize 35

36 In figure 36, PB1 is released de-energizing the Off-Delay Timer Coil instruction. The timer contacts remain in their previously energized state while the timer begins timing from its Preset Value. The contacts will remain energized until the timer times out. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE = 0 PB 1 I0.0 L1 L2 Figure 36. Off-Delay Timer Coil De-energized, Timer Timing 36

37 In figure 37, the timer s Timer Value elapses. This causes the coil and associated contacts to de-energize. As a result N.O. Contact instruction T0 opens de-energizing Output Coil instruction, and N.C. Contact instruction T0 closes energizing Output Coil instruction. As a result, Lamp L2 turns on and Lamp L1 turns off. The timer contacts will remain in their current state until the timer is again energized resetting the timer. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE = 0 PB 1 I0.0 L1 L2 Figure 37. Timer Value Reaches Preset Value, Contacts Turned Off 37

38 In figure 38, PB1 is again energizing the Off-Delay Timer Coil. The Timer contacts energize immediately and the Timer Value resets. As a result, N.O. Contact instruction T0 closes turning on Lamp L1 and N.C. Contact instruction T0 opens turning off Lamp L2. Because the timer is an Off-Delay Timer, the Timer Value remains zero. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 38. Timer-Coil Energized 38

39 In figure 39, PB1 is released de-energizing the Off-Delay Timer Coil instruction. The timer contacts remain in their previously energized state while the timer begins timing. The contacts will remain energized until the Timer Value equals zero. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 39. Off-Delay Timer Coil De-Energized Timer Timing 39

40 In figure 40, PB1 is momentarily pressed before the Off-Delay Timer times out. The contacts remain in their energized state, but the Timer Value stops decreasing. The timer must remain de-energized for 10 full seconds before its contacts are de-energized (turned off). INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 40. PB1 Pressed Momentarily, Timer Value Reset, Contacts Remain Energized 40

41 In figure 41, the instruction s Timer Value reaches zero. This causes the coil and associated contacts to de-energize. As a result N.O. Contact instruction T0 opens, de-energizing Output Coil instruction, and N.C. Contact instruction T0 closes, energizing Output Coil instruction. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 41. Timer Value Reaches Preset Value, Contacts Turned Off 41

42 SKILL 2 ENTER AND RUN A PLC PROGRAM THAT USES AN OFF-DELAY TIMER COIL INSTRUCTION Procedure Overview In this procedure, you will enter and run a PLC Program that uses an Off- Delay Timer Coil Instruction. This will teach you how the instruction works and how to enter the instruction. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 3. Start up the SIMATIC Manager. 4. Create a Project named L4S2xxx where xxx represents your initials. 5. Create an SIMATIC 300 Station object for the trainer and configure its hardware or upload the Station object by selecting Upload Station from the PLC menu (Upload Station to PG... if using STEP 7 Version 5.3 and higher). Verify that the input and output terminal addresses begin at 0 and 4 respectively. 6. Open Organization Block OB1. If you uploaded the Station object, delete all of the networks in OB1. 42

43 7. Examine the program shown in figure 42. This program is similar to the one discussed in the previous objective. In the next few steps, you will enter this program into Organizational Block OB1. OB1: TITLE: NETWORK 1: TITLE: I0.0 T0 SF S5T#10S NETWORK 2: TITLE: T0 Q4.0 NETWORK 3: TITLE: T0 Q4.1 Figure 42. PLC Program Containing Off-Delay Timer Coil Instruction 8. Click Network 1 to select it for editing. You will have to insert rung 1 if you deleted your rungs earlier. 9. Use the LAD/STL/FBD Editor to enter the N.O. Contact instruction I0.0 as shown in figure Perform the following substeps to enter the Off-Delay Timer Coil (SF) instruction shown in figure 42. A. Make sure the Program Elements Window is visible on your monitor. If it is not, make it so. B. Use the Program Elements Window s vertical scrollbar to display the Timers folder. C. Double-click the Timers folder (or click the plus sign [+] to the left of the Timers folder) to open the folder. 43

44 D. Double-click the Off-Delay Timer Coil instruction (SF) to select and insert the instruction into Network 1 of OB1. The Off-Delay Timer Coil instruction (SF) appears at the end of Network 1, its Timer Number and Time Value fields containing question marks. E. Click the Timer Number field to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter a Timer Number of T0. T0 is entered as the timer number, as the Timer Value field appears selected for editing (boxed). G. Type S5T#10S and then press Enter to enter the Off-Delay Timer s Preset Value. S5T#10S is the format for explicitly defining the Preset Value for the timer. This will cause the timer to delay for 10s or seconds before energizing its contacts. Congratulations, you have just entered an Off-Delay Timer Coil Instruction! 11. Click the New Network button (located in the LAD/STL/FBD Editor s toolbar) to insert Network 2 into the logic of OB1. Network 2 should appear on your monitor. 12. Click the network to select it for editing. 13. Perform the following substeps to place a timer contact on the newly created network. A. Click the N.O. Contact button (located in the LAD/STL/FBD Editor s toolbar) to insert the N.O. Contact instruction on Network 2. An N.O. Contact instruction appears on the rung, question marks in place of its address. B. Type T0 and then press Enter to enter the address as that of the Off-Delay Timer Coil instruction of Network 1. This contact is now associated with the timer instruction of Network 1. This means that when the Off-Delay Timer Coil times out, the contact will energize. C. Enter the remaining network logic of OB1, as shown in figure Save your PLC project. 15. Perform a memory reset on the processor. 16. Download the SIMATIC 300 Station object to the PLC. 17. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 18. Go online with the processor and monitor the OB1 block. 44

45 19. Perform the following substeps to test your new PLC Program. A. Examine the PLC program on your computer monitor. You should observe that the Off-Delay Timer Coil T0 is de-energized as are both of its contacts with the same address (on Networks 2 and 3). N.O. Contact instruction T0 is open and N.C. Contact instruction T0 is closed. Because of this, only output Q4.1 is on. B. Turn switch 1 on. This causes the N.O. Contact instruction of Network 1 (I0.0) to energize and turn on the timer instruction. Because it is an Off-Delay Timer, the timer contacts energize immediately closing N.O. Contacts T0 and opening N.C. Contacts T0. Outputs Q4.0 and Q4.1 turn on and off respectively. The timer, however, does not yet begin timing. C. Turn switch 1 off. The network containing the Off-Delay Timer instruction goes false and the timer begins timing. The timer contacts, however, are and will remain energized until the timer times out (Timer Value equals zero). Notice that the timer displays the time remaining before it will de-energize its contacts. In ten seconds, the timer times out and the Off-Delay Timers contacts are de-energized. This causes N.O. Contact instruction T0 to open (de-energizing output Q4.0) and N.C. Contact instruction T0 to close (energizing output Q4.1). The Off-Delay Timer Coil and the associated timer contacts will remain in their current condition until the Off-Delay Timer Coil instruction is re-energized (reset). D. After the timer has timed out, turn switch 1 on again. The Off-Delay Coil and its contacts are immediately energized, turning on output Q4.0 (lamp 1) and turning off output Q4.1 (lamp 2). The timer, however, will not begin timing again until the Off-Delay Timer Coil is de-energized. E. Turn switch 1 off. The network containing the Off-Delay Timer instruction goes false and the timer begins timing. The timer contacts, however, are and will remain energized until the timer times out (Timer Value elapses). Notice that the timer displays the time remaining before it will de-energize its contacts. 45

46 F. Before the timer times out, turn switch 1 on/off. The contacts remain in their energized condition, but the timer is reset. This causes the timer to restart timing. It will now be a full 10 seconds before the contacts de-energize. In ten seconds, the timer times out and the Off-Delay Timers contacts are de-energized. This causes N.O. Contact instruction T0 to open, de-energizing output Q4.0, and N.C. Contact instruction T0 to close, energizing output Q5. The Off-Delay Timer Coil and associated timer contacts will remain in their current condition until the Off-Delay Timer Coil instruction is re-energized. 20. Repeat Step 19 several times to become more familiar with the operation of the timer instruction. 21. Click the Monitor button to go offline from the processor. 22. Use the PLC programming software to place the PLC into the STOP Mode. 23. Close the LAD/STL/FBD Editor. 24. Close the SIMATIC Manager. 25. Perform the following substeps to power down the PLC trainer. A. Turn off the PC and monitor. B. Remove power from the trainer. 46

47 SEGMENT 1 SELF REVIEW 1. Timer instructions are often used in machine controls to provide a time between two events in a machine s sequence of events. 2. Two classifications of PLC timers are and timers. 3. A retentive timer accumulates (records) the total amount of time the instruction has been energized and this value even when it is de-energized. 4. Block format timer instructions have the inputs and outputs inserted around a instruction block. 5. The coil format timer instructions are displayed on the right side of a network as. 6. An On-Delay Timer Coil instruction energizes its contacts after it has been turned on for an amount of time equal to its value. 7. If the On-Delay Timer Coil instruction is de-energized before it times out, the time value is to the preset value, and the contacts are not energized. 8. The On-Delay Timer Coil instruction is often used in applications involving the of several large motors. 9. An Off-Delay Timer Coil instruction energizes its as soon as the instruction is energized. 10. If the Off-Delay Timer Coil instruction is re-energized before the preset time value has elapsed, the contacts remain, but the time value is reset to the preset time value. 47

48 SEGMENT 2 RETENTIVE ON-DELAY TIMER COIL INSTRUCTIONS OBJECTIVE 5 DESCRIBE THE OPERATION OF THE RETENTIVE ON-DELAY TIMER COIL INSTRUCTION A Retentive On-Delay Timer Coil instruction begins to time when it is first energized. The contacts remain off while the timer is timing. If the timer coil is de-energized before the preset time value has elapsed, it continues to time. The contacts energize after the preset time value has elapsed. A Retentive On-Delay Timer Coil instruction must be reset with a Reset instruction before it can be re-energized. The Siemens Retentive On-Delay Timer Coil instruction is shown in figure 43. TO SS S5T#10S Figure 43. Retentive On-Delay Timer Coil Instruction The Retentive On-Delay Timer is often used in applications where the total operating time of a machine must be tracked for preventive maintenance. It holds its Timer Value even if power to the PLC is turned off or lost. 48

49 The components of the Retentive On-Delay Timer Coil (SS) instruction are shown in figure 44, and described as follows: TIMER NUMBER RETENTIVE TIMER COIL (SS) PRESET TIME VALUE TIMER CONTACTS RESET INSTRUCTION Figure 44. Retentive On-Delay Timer Coil Instruction and Components Retentive On-Delay Timer Coil (SS) - The Timer Coil causes the timer to start timing whenever it is turned on by the network logic. Timer Number - Each timer instruction uses a number to identify it. This timer number corresponds to a memory location in the PLC. This timer location is used to store status information about the timer. Preset Time Value - With the Retentive On-Delay Timer Coil instruction (SS), the Preset Value represents the timers time delay. It represents the amount of time that the instruction must be energized before the Timer Coil is energized. The format for entering Timer Preset Values is identical to the format used for the other timers. 49

50 Timer Contacts-The timer uses associated contacts, just like coil relays. These contacts can be either N.O. or N.C. They are identified as timer contacts by using the same address as the Timer Coil. Reset Instruction-The Reset Coil instruction is an output instruction that resets retentive timer instructions having the same address. To understand how the Retentive On-Delay Timer instruction works, lets examine the example of figure 45. In this example, a PLC program with a Retentive On-Delay Timer Coil (and Reset Coil) is shown in its initial condition. Since N.O. Contact instruction I0.0 is open, the Retentive Timer Coil is not energized and the timer is not running. However, Output Coil is on because N.C. Contact T0 is closed. You should also notice that the Reset Coil (R) is de-energized at this time as well. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 PB 2 L2 I0.1 PRESET TIME VALUE Figure 45. Initial Condition of Retentive On-Delay Timer Program 50

51 In figure 46, PB1 is pressed causing N.O. Contact instruction I0.0 of Network 1 to close. There is now logical continuity to the Retentive On-Delay Timer Coil (SS) instruction T0, and the timer starts timing. The relay contacts labeled T0 on Networks 1 and 2 remain in their de-energized or normal state because the Preset Value has not yet elapsed. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 PB 2 I0.1 L2 Figure 46. Retentive On-Delay Timer Coil Energized, Timer Now Timing 51

52 In figure 47, PB1 is released. The Retentive On-Delay Timer Coil continues timing. The reason is that the Retentive On-Delay Timer Coil instruction basically seals itself in, continuing to run after being energized. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 PB 2 I0.1 L2 Figure 47. PB1 Released, Retentive On-Delay Timer Coil Remains Energized 52

53 In figure 48, the Preset Value has elapsed (timer times out) and the timer s contacts are switched to their energized state. N.O. Contact instruction T0 of Network 2 closes and N.C. Contact instruction T0 of Network 3 opens. As a result, Output Coil turns on and turns off. The timer contacts will remain energized until the Retentive On-Delay Timer Coil is reset by Reset Coil T0. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 PB 2 I0.1 L2 Figure 48. Timer Value Reaches Preset Value, Retentive On-Delay Timer Coil Energized 53

54 In figure 49, PB2 is pressed and N.O. Contact instruction I0.1 closes. This energizes the Reset Coil having the same address as the Retentive On-Delay Timer Coil (T0). This resets Retentive On-Delay Timer Coil T0. Because of this, the contacts addressed T0 (N.O. and N.C.) are de-energized and the Output Coils of Networks 2 and 3 turn off and on respectively. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 I0.1 L2 Figure 49. Reset Coil Energized, Retentive On-Delay Timer T0 Reset De-Energizing Timer Contacts 54

55 In figure 50, PB2 is released and the Reset Coil is disabled. The Retentive Timer remains de-energized and reset as does its contacts. The program is now in its initial condition. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 PB 2 I0.1 L2 Figure 50. Timer Coil Energized, Timer Now Timing 55

56 SKILL 3 ENTER AND RUN A PLC PROGRAM THAT USES A RETENTIVE ON-DELAY TIMER COIL INSTRUCTION Procedure Overview In this procedure, you will enter and run a PLC Program that uses an Retentive On-Delay Timer Coil Instruction. This will teach you how the instruction works and how to enter the instruction. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. 3. Start up the SIMATIC Manager. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 4. Create a PLC project named L4S3xxx where xxx represents your initials. 5. Create an SIMATIC 300 Station object for the trainer and configure its hardware or upload the Station object by selecting Upload Station from the PLC menu (Upload Station to PG... if using STEP 7 Version 5.3 and higher). Verify that the input and output terminal addresses begin at 0 and 4 respectively. 6. Open Organization Block OB1. If you uploaded the Station object, delete all of the networks in OB1. 56

57 7. Examine the program logic of the program shown in figure 51. This program is similar to the one discussed in the previous objective. In the next few steps, you will enter this program into Organizational Block OB1. OB1: TITLE: NETWORK 1: TITLE: I0.0 T0 SS S5T#10S NETWORK 2: TITLE: T0 Q4.0 NETWORK 3: TITLE: T0 Q4.1 NETWORK 4 : TITLE: I0.1 T0 R Figure 51. PLC Program Containing Retentive On-Delay Timer Coil Instruction 8. Click Network 1 to select it for editing. You will have to insert rung 1 if you deleted your rungs earlier. The Network should highlight. 9. Use the LAD/STL/FBD Editor to enter the N.O. Contact instruction I0.0 as shown in figure Perform the following substeps to enter the Retentive On-Delay Timer Coil instruction (shown in figure 51). A. Make sure the Program Elements window is visible on your monitor. If it is not, make it so. B. Use the Program Elements window s vertical scrollbar to display the Timers folder. C. Double-click the Timers folder (or click the plus [+] sign to the left of the Timers folder) to open the folder. 57

58 D. Double-click the Retentive On-Delay Timer Coil instruction (SS) to select and insert the instruction into Network 1 of OB1. The Retentive On-Delay Timer Coil instruction (SS) appears at the end of Network 1, its Timer Number and Time Value fields containing question marks. E. Click the Timer Number field to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter a Timer Number of T0. T0 is entered as the Timer Number and the Timer Value field appears selected for editing (boxed). G. Type S5T#10S and then press Enter to enter the Retentive On-Delay Timer s Preset Value. Congratulations, you have just entered a Retentive On-Delay Timer Coil Instruction! 11. Click the New Network button located on the LAD/STL/FBD Editor s toolbar to insert Network 2 into the logic of OB1. Network 2 should appear on your monitor. 12. Click the network to select it for editing. 13. Perform the following substeps to place a timer contact on the newly created network. A. Click the N.O. Contact button to insert the N.O. Contact instruction on Network 2. A N.O. Contact instruction appears on the rung, question marks in place of its address. B. Type T0 and then press Enter twice to enter the address as that of the Retentive On-Delay Timer Coil instruction of Network 1. This contact is now associated with the timer instruction of Network 1. This means that when the Retentive On-Delay Timer Coil times out, the contact will energize. 14. Enter the remainder of Network 2, as shown in figure Enter Network 3 of the program shown in figure Enter the N.C. Contact instruction (I0.1) of Network 4, as shown in figure Perform the following substeps to enter the Reset Coil instruction of Network 4. A. Make sure the Program Elements window is visible on your monitor. If it is not, make it so. B. Use the Program Elements window s vertical scrollbar to display the Bit Logic folder. C. Double-click the Bit Logic folder (or click the plus sign [+] to the left of the Bit Logic Folder) to open the folder. A listing of available Bit Logic instructions will be displayed in the Program Elements window. 58

59 D. Double-click the Reset Coil instruction (R) to select and insert the instruction into Network 4 of OB1. The Reset Coil instruction (R) appears at the end of Network 4, the address field containing question marks. E. Click the Reset Coil instruction s Address field to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter an address of T0. T0 is entered as the Reset Address. T0 corresponds to the Retentive On-Delay Timer Coils Address (Status Word). This means that the Reset instruction will reset timer T0 when energized. 18. Save your PLC project. 19. Perform a memory reset on the processor. 20. Download the SIMATIC 300 Station object to the PLC. 21. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 22. Go online with the processor and monitor the OB1 block. 23. Perform the following substeps to test your new PLC Program. A. Turn switch 2 on. B. Examine the PLC program on you computer monitor. You should observe that the On-Delay Timer Coil T0 is de-energized, as are both of its contacts with the same address on Networks 2 and 3. N.O. Contact instruction T0 is open and N.C. Contact instruction T0 is closed. Because of this, only output Q4.1 is on. Also notice that the Reset Coil instruction T0 is de-energized at this time. C. Turn switch 1 on and then off. This causes the N.O. Contact instruction I0.0 of Network 1 to turn on and then off, momentarily energizing the Retentive On-Delay Timer Coil. The Retentive Timer needs only to be energized momentarily as it seals in. The timer begins timing. Contacts labeled T0 remain in their de-energized state because the timer s Preset Value has not yet elapsed. In ten seconds, the timer times out and energizes any associated contact instructions. N.O. Contact instruction T0 closes energizing Output Coil Q4.0 as well as lamp 1. At the same time N.C. Contact instruction T0 opens de-energizing Output Coil Q4.1. as well as lamp 2. The Retentive On-Delay Timer Coil, the associated timer contacts, and their outputs will remain like this as long as the Reset Coil is not energized. This differs from a regular On-Delay Coil instruction in that they are reset as soon as the instruction is de-energized. 59

60 D. Turn switch 2 off. This energizes the Reset Coil instruction and resets the Retentive Timer instruction. As a result, this causes N.O. Contact instruction T0 to open, turning off output Q4.0, and N.C. Contact instruction T0 to close, turning on output Q4.1. The Reset Coil, reflecting the status of the Retentive Timer instruction, now appears de-energized. E. Turn switch 2 back on. On the monitor the Reset Coil is de-energized. This has no affect on program logic and the program is in its initial condition. 24. Repeat Step 23 several times to become more familiar with the operation of the timer instruction. 25. Click the Monitor button to go offline from the processor. 26. Use the PLC programming software to place the PLC into the STOP Mode. 27. Close the LAD/STL/FBD Editor. 28. Close the SIMATIC Manager. 29. Perform the following substeps to power down the trainer. A. Turn off the PC and monitor. B. Turn off the PLC trainer. 60

61 SEGMENT 2 SELF REVIEW 1. A Retentive On-Delay Timer Coil instruction begins to when it is first energized. 2. A Retentive On-Delay Timer Coil instruction must be reset with a Reset instruction before it can be. 3. The Retentive On-Delay Timer is often used in applications where the total operating time of a machine must be for preventive maintenance. It holds its Timer Value even if power to the PLC is turned off or lost. 4. With the Retentive On-Delay Timer Coil instruction (SS), the represents the timers time delay. It represents the amount of time that the instruction must be energized before the Timer Coil is energized. 5. The Reset Coil instruction is an output instruction that resets having the same address. 61

62 SEGMENT 3 PULSE TIMER COIL INSTRUCTIONS OBJECTIVE 6 DESCRIBE THE OPERATION OF THE PULSE TIMER COIL INSTRUCTION A Pulse Timer Coil instruction energizes its contacts immediately when enabled, and begins timing. The Pulse Timer Coil instruction de-energizes its contacts after the preset time value has elapsed. De-energizing the Pulse Timer Coil instruction while it is timing will de-energize the timer contacts and reset the timer. The Siemens Pulse Timer Coil instruction is shown in figure 52. TO SP S5T#10S Figure 52. Pulse Timer Coil Instruction One application of a Pulse Timer Coil instruction is to turn on a chemical feed pump for a certain length of time. The operator can operate a switch to turn the pump on for a pre-determined amount of time to verify that it is working. 62

63 The components of the Pulse Timer Coil instruction, are shown in figure 53 and are described as follows: TIMER NUMBER PULSE TIMER COIL (SP) PRESET TIME VALUE TIMER CONTACTS Figure 53. Pulse Timer Coil Instruction and Components Pulse Timer Coil (SP) - The Pulse Timer Coil energizes associated contacts and begins timing when enabled by the network logic. The associated contacts remain energized until the timer times out or program logic becomes false. Timer Number - Each timer instruction uses a number to identify it. This timer number corresponds to a memory location in the PLC. This timer location is used to store status information about the timer. Preset Time Value - The Timer Preset Value represents the Pulse Time, or the maximum amount of time that the timer contacts can be energized. The format for entering time values is identical to that used for the other timers. Timer Contacts - The timer uses associated contacts, just like coil relays. These contacts can be either N.O. or N.C. They are identified as timer contacts by using the same address as the timer coil. 63

64 To understand how the Pulse Timer instruction works, examine the following example. Figure 54 shows the initial condition of a PLC program that uses a Pulse Timer Coil. Since N.O. Contact instruction I0.0 is open, the Pulse Timer Coil is not energized and the timer is not running. Output Coil is on because N.C. Contact instruction T0 is closed. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 PRESET TIME VALUE Figure 54. Initial Condition of Program Containing Pulse Timer 64

65 In figure 55, PB1 is pressed causing N.O. Contact instruction I0.0 of Network 1 to close. There is now logical continuity to the Pulse Timer Coil instruction T0. The Pulse Timer Coil energizes its contacts immediately and begins timing. As a result, N.O. Contact instruction T0 closes turning on Lamp L1, and N.C. Contact instruction T0 opens turning off Lamp L2. The Pulse Timer s contacts will remain energized for 10 seconds or until the Pulse Timer is disabled, whichever is shortest. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 55. Pulse Timer Coil Enabled and Timing, Contacts Energized 65

66 In figure 56, the Pulse Timer Coil has been energized for 10 seconds. As a result, the Pulse Timer s contacts de-energize and return to the their normal condition. This causes Lamp L1 to turn off and Lamp L2 to turn on. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 56. Pulse Timer Coil Timed Out, Contacts De-Energized 66

67 In figure 57, PB1 is released. This has no affect on the Pulse Timer Coil as the contacts remain de-energized. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 57. PB1 Released, No Affect on Pulse Timer Instruction 67

68 In figure 58, pushbutton PB1 is pressed again. The Pulse Timer Coil energizes its contacts immediately and begins timing. As a result, N.O. Contact instruction T0 closes turning on Lamp L1, and N.C. Contact instruction T0 opens turning off Lamp L2. The Pulse Timer s contacts will remain energized for 10 seconds or until the Pulse Timer is disabled, whichever is shortest. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE I0.0 L1 L2 Figure 58. Pulse Timer Coil Enabled and Timing, Contacts Energized 68

69 In figure 59, pushbutton PB1 is released before the Pulse Timer times out. This causes the time value to reset and the timer to de-energize its contacts immediately. N.O. Contact instruction T0 de-energizes Output Coil, and N.C. Contact instruction T0 energizes Output Coil. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 59. Pushbutton PB1 Released Before Pulse Timer Times Out 69

70 SKILL 4 ENTER AND RUN A PLC PROGRAM THAT USES A PULSE TIMER COIL INSTRUCTION Procedure Overview In this procedure, you will enter and run a PLC Program that uses an Pulse Timer Coil Instruction. This will teach you how the instruction works and how to enter the instruction. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 3. Start up the SIMATIC Manager. 4. Create a Project named L4S4xxx where xxx represents your initials. 5. Create an SIMATIC 300 Station object for the trainer and configure its hardware or upload the Station object by selecting Upload Station from the PLC menu (Upload Station to PG... if using STEP 7 Version 5.3 and higher). Verify that the input and output terminal addresses begin at 0 and 4 respectively. 6. Open Organization Block OB1. If you uploaded the Station object, delete all of the networks in OB1. 70

71 7. Take a moment to examine the program logic of the program shown in figure 60. This program is similar to the one discussed in the previous objective. In the next few steps, you will enter this program into Organizational Block OB1. OB1: TITLE: NETWORK 1 : TITLE: I0.0 T0 SP S5T#10S NETWORK 2: TITLE: T0 Q4.0 NETWORK 3: TITLE: T0 Q4.1 Figure 60. PLC Program Containing Pulse Timer Coil Instruction 8. Click Network 1 to select it for editing. The Network should highlight. 9. Use the LAD/STL/FBD Editor to enter the N.O. Contact instruction I0.0 as shown in figure Perform the following substeps to enter the Pulse Timer Coil Instruction. A. Make sure the Program Elements window is visible on your monitor. If it is not, make it so. B. Use the Program Elements window s vertical scrollbar to display the Timer folder. C. Double-click the Timers folder (or click the plus sign [+] to the left of the Timers folder) to open the folder. 71

72 D. Double-click the Pulse Timer Coil instruction (SP) to select and insert the instruction into Network 1 of OB1. The Pulse Timer Coil instruction (SP) appears at the end of Network 1, its Timer Number and Time Value fields containing question marks. E. Click the Timer Number field to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter a Timer Number of T0. T0 is entered as the timer number, and the Timer Value field appears selected for editing (boxed). G. Type S5T#10S and then press Enter twice to enter the Pulse Timer s Preset Value. 11. Click the New Network button (located in the LAD/STL Editor s Toolbar) to insert Network 2 into the logic of OB1. Network 2 should appear on your monitor. 12. Click the network to select it for editing. 13. Perform the following substeps to place a timer contact on the newly created network. A. Click the N.O. Contact button (located in the LAD/STL Editor s toolbar) to insert the N.O. Contact instruction on Network 2. An N.O. Contact instruction should appear on the rung with question marks in place of its address. B. Type T0 and then press Enter twice to give the N.O. Contact instruction the same address as the Pulse Timer Coil instruction of Network 1. This contact is now associated with the timer instruction of Network Enter the remaining network logic of OB1, as shown in figure Save your PLC project. 16. Perform a memory reset on the processor. 17. Download the SIMATIC 300 Station object to the PLC. 18. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 19. Go online with processor and monitor the OB1 Block. 20. Perform the following substeps to test your new PLC Program. A. Examine the PLC program on your computer monitor. You should observe that the Pulse Timer Coil T0 is de-energized, as are both of its contacts having the same address on Networks 1 and 2. N.O. Contact instruction T0 is open and N.C. Contact instruction T0 is closed. Because of this, only output Q4.1 is on. 72

73 B. Turn switch 1 on. This causes the N.O. Contact instruction of Network 1 (I0.0) to energize and turn on the timer instruction. Because it is a Pulse Timer, the timer immediately begins timing. Output Coil Q4.0 energizes and Output Coil Q4.1 de-energizes. After 10 seconds, the Pulse Timer times out and de-energizes its contacts. As a result, the N.O. Contact instruction T0 opens de-energizing Output Coil Q4.0, and N.C. Contact instruction T0 closes energizing Output Coil Q4.1. C. Turn switch 1 off. Other than de-energizing N.O. Contact instruction I0.0, this has no effect on program logic. The Pulse Timer s contact instructions remain de-energized, Output Coil Q4.0 remains off, and Output Coil Q4.1 remains on. The timer and its contacts will remain like this until the instruction is re-energized. D. Turn switch 1 on again. The Pulse Timer Coil begins timing as its contacts are energized. Output Coil Q4.0 energizes and Output Coil Q4.1 de-energizes. E. Before the timer has timed out, turn switch 1 off again. The Pulse Coil and its contacts de-energize immediately. This causes output Q4.0 (lamp 1) to turn off and output Q4.1 (lamp 2) to turn on. The timer value is also reset. 21. Repeat Step 20 several times to become more familiar with the operation of the timer instruction. 22. Click the Monitor button to go offline from the processor. 23. Use the PLC programming software to place the PLC into STOP Mode. 24. Close the LAD/STL/FBD Editor. 25. Close the SIMATIC Manager. 26. Perform the following substeps to power down the PLC trainer. A. Turn off the PC and monitor. B. Turn off the PLC trainer. 73

74 OBJECTIVE 7 DESCRIBE THE OPERATION OF THE EXTENDED PULSE TIMER COIL INSTRUCTION An Extended Pulse Timer Coil instruction energizes its contacts immediately when it is enabled, and begins timing at this same instant. The Extended Pulse Timer Coil instruction de-energizes its contacts after the preset time value has elapsed. De-energizing the Extended Pulse Timer Coil instruction while it is timing has no effect, it is sealed in until the preset time value has elapsed. The Siemens Extended Pulse Timer Coil instruction is shown in figure 61. TO SE S5T#10S Figure 61. Extended Pulse Timer Coil Instruction One application of the Extended Pulse Timer Coil instruction is to flash a set of lamps on or off for alarm purposes. 74

75 The components of the Extended Pulse Timer Coil instruction are shown in figure 62 and are described as follows: TIMER NUMBER EXTENDED PULSE TIMER COIL (SE) PRESET TIME VALUE TIMER CONTACTS Figure 62. Extended Pulse Timer Coil Instruction and Components Extended Pulse Timer Coil - The Extended Pulse Timer Coil energizes its contacts immediately after being enabled and seals itself in. Once energized, the instruction runs until it times out, resetting its contacts. Timer Number - Each timer instruction uses a number to identify it. This timer number corresponds to a memory location in the PLC. This timer location is used to store status information about the timer. Preset Time Value - The Timer Preset Value represents the Pulse Time, or the maximum amount of time that the timer contacts can be energized. The format for entering time values is identical to that used for the other timers. Timer Contacts - The timer uses associated contacts, just like coil relays. These contacts can be either N.O. or N.C. They are identified as timer contacts by using the same address as the timer coil. 75

76 Figure 63 shows the initial condition of a PLC program that uses an Extended Pulse Timer Coil. Since N.O. Contact instruction I0.0 is open, the Extended Pulse Timer is not energized, and therefore, not running. Output Coil is on because N.C. Contact instruction T0 is closed. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 PRESET TIME VALUE Figure 63. Initial Condition of Program Containing Extended Pulse Timer 76

77 In figure 64, PB1 is pressed causing N.O. Contact instruction I0.0 of Network 1 to close. There is now logical continuity to Extended Pulse Timer instruction T0 and the timer is energized. The Extended Pulse Timer Coil energizes its contacts immediately and begins timing. This causes N.O. Contact instruction T0 to close, turning on Lamp L1, and N.C. Contact instruction T0 to open, turning off Lamp L2. The Extended Pulse Timer s contacts will remain energized even if logic continuity is lost by releasing PB1. INPUTS PLC PROGRAM OUTPUTS PB 1 TIMER VALUE L1 I0.0 L2 Figure 64. Extended Pulse Timer Coil Enabled and Timing Contacts Energized 77

78 In figure 65, PB1 is released. Even though logic continuity is lost from the Extended Pulse Timer Coil, it remains energized and timing. The coil will remain energized and timing until the instruction times out after 10 seconds. Lamp L1 remains on and Lamp L2 remains off. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 65. PB1 Released, Extended Pulse Timer Coil Remains Energized and Timing 78

79 After 10 seconds, the Extended Pulse Timer instruction times out and its contacts de-energize. As a result, the N.O. Contact instruction T0 opens, and N.C. Contact instruction T0 closes. This causes Lamp L1 to turn off and Lamp L2 to turn on, as shown in figure 66. The Extended Pulse Timer Coil and its associated contacts will remain in this condition until PB1 is pressed again. INPUTS PLC PROGRAM OUTPUTS TIMER VALUE PB 1 I0.0 L1 L2 Figure 66. PB1 Released, Extended Pulse Timer Coil Remains Energized and Timing 79

80 SKILL 5 ENTER AND RUN A PLC PROGRAM THAT USES AN EXTENDED PULSE TIMER COIL INSTRUCTION Procedure Overview In this procedure, you will enter and run a PLC Program that uses an Extended Pulse Timer Instruction. This will teach you how the instruction works and how to enter the instruction. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 3. Start up the SIMATIC Manager. 4. Create a Project named L4S5xxx where xxx represents your initials. 5. Create an S7 Station object for the trainer and configure its hardware or upload the Station object by selecting Upload Station from the PLC menu. Verify that the input and output terminal addresses begin at 0 and 4 respectively. 6. Open Organization Block OB1. If you uploaded the Station object, delete all of the networks in OB1. 80

81 7. Examine the program logic shown in figure 67. This program is similar to the one discussed in the previous objective. In the next few steps, you will enter this program into Organizational Block OB1. 8. Click Network 1 to select it for editing. Q4.0 Q4.1 Figure 67. PLC Program Containing Extended Pulse Timer Instructions The Network should highlight. 9. Use the LAD/STL/FBD Editor to enter the N.O. Contact instruction I0.0 as shown in figure Perform the following substeps to enter the Extended Pulse Timer Coil instruction. A. Make sure the Program Elements window is visible on your monitor. If it is not, make it so. B. Use the Program Elements window s vertical scrollbar to display the Timer folder. C. Double-click the Timers folder (or click the plus sign [+] to the left of the Timers folder) to open the folder. D. Double-click the Extended Pulse Timer instruction (SE) to select and insert the instruction into Network 1 of OB1. The Extended Pulse Timer Coil instruction (SE) appears at the end of Network 1, its Timer Number and Time Value fields containing question marks. 81

82 E. Click the Timer Number field to select it for editing. A box appears where the question marks were earlier. F. Type T0 and then press Enter twice to enter a Timer Number of T0. T0 is entered as the timer number, and the Timer Value field appears selected for editing (boxed). G. Type S5T#10S and then press Enter to enter the Extended Pulse Timer s Preset Value. This will cause the Extended Pulse Timer Coil instruction to delay for 10 seconds before de-energizing its contacts. Congratulations, you have just entered an Extended Pulse Timer Coil Instruction! 11. Click the New Network button (located in the LAD/STL Editor s toolbar) to insert Network 2 into the logic of OB1. Network 2 should appear on your monitor. 12. Click the network to select it for editing. 13. Perform the following substeps to place a timer contact on the newly created network. A. Click the N.O. Contact button (located on the LAD/STL/FBD Editor s toolbar) to insert the N.O. Contact instruction on Network 2. An N.O. Contact instruction appears on the rung, question marks in place of its address. B. Type T0 and then press Enter to give the N.O. Contact the same address as the Extended Pulse Timer Coil instruction of Network 1. This contact is now associated with the timer instruction of Network 1. This means that when the Extended Pulse Timer Coil times out, the contact will energize. C. Enter the remaining network logic of OB1, as shown in figure Save your PLC project. 15. Perform a memory reset on the processor. 16. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 17. Download the SIMATIC 300 Station object to the PLC. 18. Go online with the processor and monitor the OB1 block. 19. Perform the following substeps to test the operation of the Extended Pulse Timer instruction. A. Examine the PLC program on your computer monitor. You should observe that the Extended Pulse Timer T0 is currently de-energized as are both of its contacts having the same address (on Networks 2 and 3). N.O. Contact instruction T0 is open and N.C. Contact instruction T0 is closed. Because of this, only output Q4.1 is on. 82

83 B. Turn switch 1 on. This causes the N.O. Contact instruction of Network 1 (I0.0) to energize, turning on the Extended Pulse Timer instruction. The timer, now enabled, energizes associated contacts and begins timing. N.O. Contact instruction T0 closes turning on lamp 1, and N.C. Contact instruction T0 opens turning off lamp 2. Because it is an Extended Pulse Timer, the coil will remain enabled until it times out, regardless of logic continuity. After 10 seconds, the Extended Pulse Timer times out and de-energizes its contacts. As a result, the N.O. Contact instruction T0 opens de-energizing Output Coil Q4.0, and N.C. Contact instruction T0 closes energizing Output Coil Q4.1. C. Turn switch 1 off. Other than de-energizing N.O. Contact instruction I0.0, this has no effect on program logic. The Extended Pulse Timer s contact instructions remain de-energized, Output Coil Q4.0 remains on, and Output Coil Q4.1 remains off. The timer and its contacts will remain like this until the instruction is re-energized. D. Turn switch 1 on again. The Extended Pulse Timer Coil begins timing as its contacts are energized. Output Coil energizes and Output Coil de-energizes. E. Before the timer has timed out, turn switch 1 off. The Extended Pulse Coil remains energized and continues timing. The coil remains energized and timing until the instruction times out. After it times out, output Q4.0 (lamp 1) turns off and output Q4.1 (lamp 2) turns on. 20. Repeat Step 19 several times to become more familiar with the operation of the timer instruction. 21. Click the Monitor button to go offline from the processor. 22. Use the PLC programming software to place the PLC into STOP Mode. 23. Close the LAD/STL/FBD Editor. 24. Close the SIMATIC Manager. 25. Perform the following substeps to power down the PLC trainer. A. Turn off the PC and monitor. B. Turn off the PLC trainer. 83

84 SEGMENT 3 SELF REVIEW 1. A Pulse Timer Coil instruction energizes its contacts when enabled, and begins timing. 2. The Pulse Timer Coil instruction its contacts after the preset time value has elapsed. 3. De-energizing the Pulse Timer Coil instruction while it is timing will de-energize the timer and reset the timer. 4. An Extended Pulse Timer Coil instruction energizes its contacts when it is enabled, and begins timing at this same instant. 5. The Extended Pulse Timer Coil instruction its contacts after the preset time value has elapsed. 6. De-energizing the Extended Pulse Timer Coil instruction while it is timing has effect, it is sealed in until the preset time value has elapsed. 84

85 SEGMENT 4 TIME-DRIVEN SEQUENCING OBJECTIVE 8 DEFINE TIME-DRIVEN SEQUENCING AND GIVE THREE APPLICATIONS PLC programs can use timers as well as limit switches to sequence events. Sequencing using timers is called time-driven sequencing. For example, a heat treatment process might use the following three-step sequence. Each step is performed one after the other. The trigger for the process to move to the next step in the sequence is a preset time delay. HEAT TREATMENT SEQUENCE STEP ACTION TIME DURATION (MIN) 1 Heat at 500 C 30 2 Heat at 300 C 15 3 Cool 45 Figure 68. Heat Treatment Sequence Time-driven sequencing can be used to control operations that are based on time, such as the heating, cooling, or mixing of materials. Time-driven sequencing can also be used in applications where actuator positioning is not consistent enough to use limit switches for event-driven sequencing. 85

86 OBJECTIVE 9 DESCRIBE THE OPERATION OF A TIME-DRIVEN SEQUENCE PROGRAM A PLC time-driven sequencing program can be designed by using a series of timer instructions with each instruction controlling an event in the sequence. As an example, let s consider the paint mixing application shown in figure 70. As shown in the following sequence of operation, two colors are mixed to yield a custom color. PAINT MIX SEQUENCE OF OPERATION STEP INPUT OUTPUT 1 Operator presses PB1 Both paints are pumped into the vat second timer times out The paint in the vat is mixed 3 30 second timer times out The process turns off and the program resets Figure 69. Paint Mix Sequence of Operation BASE COLOR PAINT MIX COLOR PAINT BASE COLOR PUMP MIXING VAT MIX COLOR PUMP "MIXER" MOTOR Figure 70. Pictorial of Paint Mixing Application 86

87 The PLC program shown in figure 71 will perform the three-step paint mix sequence just described. As you can see, two SD instructions are used to create the sequence. INPUTS PLC PROGRAM OUTPUTS PB1 START OB1: TITLE NETWORK 1: TITLE: I0.1 T1 I0.0 M0.0 PUMP 1 I0.0 L1 M0.0 PUMP 2 PB2 STOP I0.1 NETWORK 2: TITLE: M0.0 T0 SD Q5.6 L2 MIXER MOTOR L3 S5T#12S500 MS NETWORK 3: TITLE: M0.0 T0 NETWORK 4: TITLE: T0 T1 SD S5T#30S NETWORK 5: TITLE: T0 Q5.6 Figure 71. PLC Program for Paint Mixing Application 87

88 Activity 1. Operation of a Time-Driven Sequence Program Procedure Overview In this procedure, you will enter and run a PLC program similar to the one just described in the objective. This will allow you to see how time-driven sequencing works. You will use the 87-IOS exclusively to perform this skill. 1. Perform the following substeps to prepare the trainer for use. A. Verify that the Portable Mounting Console and 87-IOS are connected. B. Make sure that the PLC power cable is connected to the PLC and plugged into an outlet. C. Verify that the PLC power cable s toggle switch is in the off position. D. Make sure that the Interface cable is connected from the PC to the PLC. E. Make sure that all of the 87-IOS Station s switches are in the off (down) position. 2. Power up the PLC trainer. WARNING Most PLC applications require an organized startup and shutdown procedure to avoid personal injury and/or damage to the machinery. Be certain to follow these procedures when in the field. 3. Start up the SIMATIC Manager. 4. Create a Project named L4A1xxx where xxx represents your initials. 5. Create an SIMATIC 300 Station object for the trainer and configure its hardware or upload the Station object by selecting Upload Station from the PLC menu (Upload Station to PG... if using STEP 7 Version 5.3 and higher). Verify that the input and output terminal addresses begin at 0 and 4 respectively. 6. Open Organization Block OB1. If you uploaded the Station object, delete all of the networks in OB1. 88

89 7. Enter the ladder logic of figure 72 into OB1. INPUTS PLC PROGRAM OUTPUTS PB1 START I0.0 OB1: TITLE NETWORK 1: TITLE: I0.1 T1 I0.0 M0.0 Q4.0 PUMP P1 L1 PB2 STOP I0.1 M0.0 NETWORK 2: TITLE: M0.0 T0 SD Q4.1 Q4.2 PUMP P2 L2 MIXER MOTOR L3 S5T#12S500 MS NETWORK 3: TITLE: M0.0 T0 Q4.0 Q4.1 NETWORK 4: TITLE: T0 T1 SD S5T#30S NETWORK 5: TITLE: T0 Q4.2 Figure 72. Time-Sequencing Program 8. Save your PLC project. 9. Perform a memory reset on the processor. 10. Download the SIMATIC 300 Station object to the PLC. 11. Use the PLC programming software to perform a Warm Restart to place the PLC into RUN Mode. 12. Go online with the processor and monitor the OB1 block. 13. Perform the following substeps to test the operation of your PLC program. 89

90 A. Turn switch 2 on to simulate a N.C. pushbutton. B. Take a moment to examine the initial condition of the PLC program on your monitor. At this time, you should notice that only three instructions are logically true at this time: N.O. Contact instruction I0.1 of Network 1, the N.C. Contact instruction T1 of the same network, and N.C. Contact instruction T0 of Network 3. As a result no outputs are or timer instructions are energized at this time, as shown in figure 73. Try and think through the program logic before continuing to substep C. INPUTS PLC PROGRAM OUTPUTS PB1 START PUMP P1 I0.0 Q4.0 L1 PUMP P2 PB2 STOP I0.1 Q4.1 L2 MIXER MOTOR Q4.2 L3 Q4.0 Q4.1 Q4.2 Figure 73. Initial Condition of the Time-Driven Event Sequencing Program 90

91 C. As you view the monitor, turn switch 1 on and off to simulate the operation of a N.O. pushbutton. On the monitor, N.O. Contact instruction I0.0 energizes, turning Network 1 logically true. This energizes Memory Coil M0.0 and its contacts. The N.O. Contact instruction M0.0 of Network 1 seals-in the Memory Coil while the N.O. Contact instruction M0.0 of Networks 2 and 3 energize On-Delay Timer Coil T0 and Output Coils Q4.0 and Q4.1 respectively. As a result, Pumps P1 and P2 are turned on, as shown in figure 74. INPUTS PLC PROGRAM OUTPUTS PB1 START PUMP P1 I0.0 Q4.0 L1 PUMP P2 PB2 STOP I0.1 Q4.1 L2 MIXER MOTOR Q4.2 L3 Q4.0 Q4.1 Q4.2 Figure 74. Step 1: Outputs Q4.0 and Q4.1 Energized, System Pumps Both Paints 91

92 After 12 1/2 seconds, timer T0 times out and energizes its contacts. This causes N.C. Contact instruction T0 of Network 3 to open, de-energizing Output Coil instructions Q4.0 and Q4.1 and cutting power to the pumps. At the same time, N.O. Contact instruction T0 energizes on Network 4, energizing On-Delay Timer Coil T1 and Output Coil Q4.2. The timer begins timing and the mixer motor (lamp 3) turns on. Notice that timer T0 has not yet been reset because N.O. Contact instruction M0.0 keeps it energized. This is necessary for this particular program to work properly. INPUTS PLC PROGRAM OUTPUTS PB1 START STEP 1A: CONTACT T1 OPENS RESETTING MEMORY COIL M0.0 PUMP 1 I0.0 Q4.0 L1 PB2 STOP I0.1 STEP 3B: N.C. CONTACT T1 CLOSES, RESETTING PROGRAM TO INITIAL CONDITION STEP 2: MEMORY COIL M0.0 RESETS STEP 3: TIMER T0 DE-ENERGIZES Q4.1 Q4.2 PUMP 2 L2 "MIXER" MOTOR L3 STEP 2A: CONTACTS M0.0 OPEN WHEN MEMORY COIL M0.0 IS RESET, TURNING OFF TIMER T0 Q4.0 Q4.1 STEP 1: ON DELAY TIMER TIMES OUT STEP 3A: TIMER CONTACTS T0 TURN OFF RESETTING TIMER T1 AND OUTPUT Q4.2 Q4.2 Figure 75. Step 2: Outputs Q4.0 and Q4.1 Off, Output Q4.2 On, Mixing Paint 92

93 After 30 more seconds, On-Delay Timer T1 times out. This causes the N.C. Contact instruction T1 of Network 1 to open, breaking the network s logic continuity, and completing the process. When Timer T1 is reset, it starts a three-step process that is designed to reset the program. These steps are shown in figure 76 and described as follows: Step 1 - When On-Delay Timer T1 times out and energizes its coil, it causes the N.C. Contact instruction (T1) of Network 1 to open, cutting power to Memory Coil M0.0. Step 2 - As Memory Coil M0.0 de-energizes, so do the N.O. Contact instructions associated with it on Networks 1, 2, and 3. On Network 1 the circuit seal-in is opened. On Network 3, N.O. Contact instruction M0.0 opens. This, however, has no effect on Network 3 as the coil instructions are already off. On Network 2, the N.O. Contact instruction M0.0 cuts logical continuity to Timer T0, resetting the timer and its contacts on Networks 3 and 4. Step 3 - Because Timer T0 is now de-energized, it causes the N.C. Contact instruction T0 of Network 3 to close. This has no effect on the Network as N.O. Contact instruction M0.0 is open. When the N.O. Contact instruction T0 of Network 4 opens, it de-energizes Output Coil Q4.2 and On-Delay Timer instruction T1, resetting the timer and de-energizing its contact. This causes N.C. Contact instruction T1 of Network 1 to close, resetting the program to its initial condition. 93

94 INPUTS PLC PROGRAM OUTPUTS PB1 START STEP 1A: CONTACT T1 OPENS RESETTING MEMORY COIL M0.0 PUMP 1 I0.0 Q4.0 L1 PB2 STOP I0.1 STEP 3B: N.C. CONTACT T1 CLOSES, RESETTING PROGRAM TO INITIAL CONDITION STEP 2: MEMORY COIL M0.0 RESETS STEP 3: TIMER T0 DE-ENERGIZES Q4.1 PUMP 2 L2 "MIXER" MOTOR Q4.2 L3 STEP 2A: CONTACTS M0.0 OPEN WHEN MEMORY COIL M0.0 IS RESET, TURNING OFF TIMER T0 Q4.0 Q4.1 STEP 1: ON DELAY TIMER TIMES OUT STEP 3A: TIMER CONTACTS T0 TURN OFF RESETTING TIMER T1 AND OUTPUT Q4.2 Q4.2 Figure 76. Three-Step Process Complete, All Outputs Off D. Repeat substeps B and C several times to become familiar with the operation of a time-driven sequencing program. During one cycle, turn switch 2 off momentarily while the program is running. You should notice that the program stops and resets to its initial condition. 14. Click the Monitor button to go offline from the processor. 15. Use the PLC programming software to place the PLC into the STOP Mode. 16. Close the LAD/STL/FBD Editor. 17. Close the SIMATIC Manager. 18. Perform the following substeps to power down the PLC trainer. A. Turn off the PC and monitor. B. Turn off the PLC trainer. 94

95 SKILL 6 DESIGN A PLC PROGRAM THAT PROVIDES LOW VOLTAGE STARTING OF AN ELECTRIC MOTOR Procedure Overview In this procedure, you will design a PLC program that uses a timer instruction to start an electric motor under low voltage. You will use the 87-IOS exclusively to perform this skill. 1. Examine the following information. Scenario: If an electric motor is connected directly to line voltage, the startup current of the motor may be 4 to 10 times greater than the full load rating of the motor. This inrush of current may increase the power bill of a company greatly since many utility companies charge according to the peak current used. Therefore, methods have been developed to reduce the starting current of a motor. One way is to use a reduced voltage auto transformer motor starter, as shown in figure

96 The basic principle of a reduced voltage starter is to apply a portion of the total voltage to start. After the motor begins rotating, the motor leads are switched to apply the full line voltage. One method of providing reduced voltage starting is to use a transformer that steps down the voltage. Reduced voltage starters usually use an auto transformer. An auto transformer is a transformer that contains one set of windings that are shared by the primary and secondary. PLC timers are often used to provide control (switching) of the auto transformer reduced voltage starter by switching the transformer from low voltage to the full voltage after a predetermined time delay. Figure 77. Reduced Voltage Auto Transformer Starter (Photo Courtesy of Allen Bradley Co.) 96