RsLogix 500 - Sequencing Machine Steps Part 4 - Counters

In this lesson you will dive deep into how the LAD 5 COUNTER routine of the previous RsLogix 500 - Sequencing Machine Steps uses counters to sequence through steps.

1.  Download the CougarTurnSignalCounter.RSS file.  This is a simplified version of the RSS file you used in the Sequencing Machine Steps lesson, only including the counter sequence programming.

2.  Open the RSS file in RsLogix 500, download it to your PLC, switch the PLC to Run Mode, and Go Online.

3.  Open up the LAD 5 COUNTER routine.

4.  Turn on I:0/0.  It should still be wired to the Green button from the previous lesson.

5.  Your screen should be sequencing through rungs 0-5 similarly to the video below.  You may have to right click the image below and open a new tab depending on your browser.

counterturnsignal.gif

 

Below is the explanation of how the counter keeps track of which step in the sequence the PLC is on.  We are ignoring the XIC I:0/0 left turn signal in the explanation below for simplicity.

Rung 1-4 - Each of these rungs work very similarly.  The EQU instructions makes sure that the counter doesn't increment on the wrong step.  Then there is a timer that the EQU enables, and once the timer is done, it enables the counter which increments the counter, immediately making that rung false since the EQU instruction at the beginning is not longer true.

Rung 5 - Once the counter equals 4, it performs a RES reset instruction on the counter, setting it's ACC back to "0" and making the EQU in rung 1 true again, repeating the process.

 

Conclusion

Continue to the next lesson, RsLogix 500 - Sequencing Machines Part 5 - Word/Bit Manipulation.

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