EET3370 – Programmable Logic Controller Basics

 

Lab 6 – SLC 500 Counters

 

PURPOSE:

 

The purpose of this lab is to introduce you to the counter functions available in the SLC 500 instruction set.  In this lab, you will program each of a series of counting circuits in the SLC and will demonstrate it with the use of the interface panel.

 

APPLICABILITY CRITERIA:

 

The functions in this lab allow you to program counting functions used commonly for parts tracking and material handling operations.  The counter functions also enable you to program event and event/time-driven sequencing circuits.

 

PROCEDURE:

 

1.  [_____]  Create a new file on the SLC 500.

 

2.  [_____]  Enter the program shown below.  The count up command is found under timer/counter (F2).  You want to use the count up (CTU, F4) counter.  You will set the preset value to 5 and the accumulator value to zero.

 

 

           I:1

     |----] [-------------------+CTU------------------+      |

     |       0                  +Count Up Counter     +-(CU)-|

     |                          |Counter        C5:0  |      |

     |                          |Preset        5      +-(DN) |

     |                          |Accum         0      |      |

     |                          +---------------------+      |

     |                                                       |

     |    I:1                                       C5:0     |

     |----] [---------------------------------------(RES)----|

     |      1                                                |

     |   C5:0/DN                                   O:2/0     |

     |----] [---------------------------------------(  )-----|

     |                                                       |

 

 

2a. [_____]  Wire toggle switches to inputs as required.

 

3.  [_____]  Turn all toggle switches on the demo unit OFF.  Download program and then go to the RUN mode.

 

4.  [_____]  Turn Input I:1/1 ON and then back OFF.  Toggle Input I:1/0 on and off, counting the number of OFF-to-ON transitions before Output 0 energizes.  Verify the Preset Value is 5.

 

5.  [_____]  Monitor the ACCUMULATE VALUE of CTU 5:0.

 

6.  [_____]  Turn Input I:1/1 ON and then back OFF.

 

7.  [_____]  Verify that the Accumulate Value returns to 0000.

 

8.  [_____]  Toggle Input 0 on and off, verifying that the value increments from 0000 UPWARD on the programmer display, and that Output 2/0 energizes on a count of 0005.

 

9.  [_____]  Continue toggling Input 0, observing that the Accumulate Value continues to increment past the Preset Value.

 

10. [_____]  Does Output 0 de-energize when the Accumulate Value increments beyond the Preset Value? ____________

 

10a.[_____]  Turn Input I:1/1 ON .  Toggle Input I:1/0 on and off 5 times.  Does the Output 0 energize?  Explain.

 

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11. [_____]  Append the following ladder diagram to your previous program.

    

 

     | C5:0/CU                                 O:2/1     |

     |--] [------------------------------------(   )-----|

     |                                                   |

     | C5:0/OV                                 O:2/2     |

     |--] [------------------------------------(   )-----|

     |                                                   |

 

 

12. [_____]  When you have finished adding these rungs, download the program and monitor the rungs.

 

13. [_____]  The Count Up bit (CU) comes active whenever the counter counts.  The Over Flow (OV) bit comes true only when the counter accumulated value is greater than 32767.  We will not push the button that many times but you should be aware of it’s use.

 

14. [_____]  Which output(s) will energize when input I:1/0 is high?  ____________

 

15. [_____]  Which output will energize when the counter accumulate value is greater than the preset?  _________

 

16. [_____]  If the accumulated value were 32760 how many times must the input I:1/0 be pushed before output O:2/2 is energized?  ___________

 

17. [_____]  What happens when input I:1/1 is energized?

 

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18. [_____]  In the space below, draw a ladder diagram which uses two counters to count a total of 16 events.  The "events" are simulated with I:1/3 (THE COUNT INPUT).  The first counter should count 9 transitions of Input 3, and the second counter should count the remaining transitions of Input 3.  Use I:1/4 as the RESET INPUT for the first counter and have a status bit from the first counter reset the second counter. The second counter should not be allowed to function until the first has reached its Preset Value.  Use C5:0 for the first counter and C5:1 for the second counter.  O:2/5 should energize only after all sixteen counts have occurred.

 

19. [_____]  Enter the program in the computer, and transfer the program to the SLC 500

 

20. [_____]  When you get it working correctly have your instructor initial your ladder diagram.

 

21. [_____]  Monitor the Accumulate Value of C5:0 and toggle I:1/3 eight (8) times, verifying that the value increments to 0008.

 

22. [_____]  Toggle I:1/3 once more and verify that C5:0 is energized, and C5:1 has an Accumulate value of 0001.  Continue toggling I:1/3 and verify that O:2/5 energizes on a total count of 16.

 

23.  [_____]  Enter and transfer the following program:

 

|   I:1/1    T4:0/DN                                    |

|---]  [------]/[-----------+TON-----------------+      |

|                           +Timer On Delay      +-(EN)-|

|                           |Timer        T4:0   +      |

|                           |Time base    0.01   +-(DN) |

|                           |Preset       1000   |      |

|                           |Accum        0      |      |

|                           +--------------------+      |

| T4:0/DN                                               |

|---] [---------------------+CTU-----------------+      |

|                           +Count Up Counter    +-(CU)-|

|                           |Counter       C5:0  |      |

|                           |Preset        1000  +-(DN) |

|                           |Accum         0     |      |

|                           +--------------------+      |

|                                                       |

| I:1/1                                      C5:0       |

|---]/[--------------------------------------(RES)------|

|                                                       |

| C5:O/DN                                     O:2/7     |

|---] [---------------------------------------(  )------|

    

 

 

24.  [_____]  In the space below, write a description of the purpose and the operation of the circuit.

 

    _______________________________________________________

 

    _______________________________________________________

   

 

25.  [_____]   What would be the approximate time for C5:0 to reach its preset value if I:1/1 closed now? _________________________

   


 

26.  [_____] Place the control below in the PLC.         

               

   T4:1

|---]/[----------------+TON-----------------+      |

|      DN              +Timer On Delay      +-(EN)-|

|                      |Timer        T4:1   +      |

|                      |Time base    0.01   +-(DN) |

|                      |Preset       1      |      |

|                      |Accum        0      |      |

|                      +--------------------+      |

| T4:1/DN                                          |

|---] [----------------+CTU-----------------+      |

|                      +Count Up Counter    +-(CU)-|

|                      |Counter       C5:0  |      |

|                      |Preset        1000  +-(DN) |

|                      |Accum         0     |      |

|                      +--------------------+      |

| C5:0/DN                                          |

|---] [----------------+CTU-----------------+      |

|                      +Count Up Counter    +-(CU)-|

|                      |Counter       C5:1  |      |

|                      |Preset        1000  +-(DN) |

|                      |Accum         0     |      |

|                      +--------------------+      |

| C5:0/DN                                          |

|---] [---+                                        |

|         |                                        |

| I:1/3   |                           C5:0         |

|---]/[---+---------------------------(RES)--------|

|                                                  |

|                                                  |

| I:1/3                               C5:1         |

|---]/[-------------------------------(RES)--------|

|                                                  |

| C5:1/DN                              O:2/6       |

|---] [--------------------------------(  )--------|

|   

 

27. [_____]  How does the circuit above differ from the previous one.  Hint:  Is there difference in resolution?  What is the same?

 

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