RS Logix 500, Programming Questions

For a school project, i have to program a small station that puts covers on parts.

One requierment is, if the stop button is pressed, the operation stops, then resume from where it left off again once start is pressed again, for some reason i cannot think of a simple way to to this while maintaining it's position in the program, and holding all outputs where ever they may be.

One more thing, i have approximetly 4 sequencers programed for the station and was thinking of making them subroutines. by using a jsr to jump to it, and possibly have for example to run the next step once the sequencer is done an equal like R6:0.POS = 6, and was wondering if it is at all possible, or am i merely overcomplicating things.

Note: The PLC is a MicroLogix 1500 LRP Series C

HeAd_ShOt said:

For a school project, i have to program a small station that puts covers on parts.

One requierment is, if the stop button is pressed, the operation stops, then resume from where it left off again once start is pressed again, for some reason i cannot think of a simple way to to this while maintaining it's position in the program, and holding all outputs where ever they may be.

One more thing, i have approximetly 4 sequencers programed for the station and was thinking of making them subroutines. by using a jsr to jump to it, and possibly have for example to run the next step once the sequencer is done an equal like R6:0.POS = 6, and was wondering if it is at all possible, or am i merely overcomplicating things.

Note: The PLC is a MicroLogix 1500 LRP Series C

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To resume where the process left off, use the start/stop to set a 'run' bit, and a separate bit to represent each step's start and completion. So to start a step, you'll need to test if the previous step is completed (and any other conditions there may be) and the 'run' bit is enabled. Personally, I would only use XIO/XIC and OTE for something like that, and try to avoid using OTL/OTU.

Also, I don't quite follow your sequencer/subroutine explanation. Are the sequencers required by the project? Or were you using them to track the steps? IMO, I would avoid using the sequencer instructions unless they were required by the class project. Most projects I've worked on didn't need them, or they wouldn't work well in the application. They can also be very difficult for others to follow (much less troubleshoot).

I've had a lot of experience with AB processors, but it's been over 18 months since I've used one. And even then I didn't use the sequencing instructions. But if you need to use them I think you need a separate R6 register for each sequencer (if you haven't figured that out). And I do like sensible use of subroutines. For me, they make programs so much easier to break out into sections for troubleshooting.

Hope this helps, and isn't as clear as mud (it's late, I'm tired). Good luck!

We recently learned sequencers in class, and we have the choice to use them if we want, there are 4 simple task that would take alot of ladder to right, and i found it easier to write the sequencers for them. I am trying to keep the program tidy, so that's why i would like to put the 4 sequencers in seperate subroutines that the program can jump to when the operation is needed.