micrologix pto problem - please help

hello all, im really in a bind here

I'm using a micrologix 1100 to send pulses to a stepper driver for a indexing application. What I do is use the PTO jog to index until a fiber detects the cut position then send a number of pulses to index the product (desiccant) to the cutter blade using the PTO command. This works fine without a problem.

This is my problem, when the desiccant gets to the cutter it hangs sometimes on the cutter. What i need to do is run the stepper backwards just a small amount and everything would be good. So I do this in the program, change direction though a output to the stepper driver, change the PTO:0:top pulses and run the PTO. I thought this would be simple but its not working. Sometimes it works sometimes it doen't

My questions are these:
1 - I am using the micrologix free software for programming, is there any problem i should be aware of using this rather than a full 500 software.
2 - I'm using the PTO command in different rungs, is this ok? should i only have it in one rung and have different triggers
3 - Does anyone have or be willing to write a quick and simple program to run 1 direction so many pulses than run reverse so many pulses. an output is all i change state of to change direction

If anyone could please help me I would be eternally great full

Thanks for your time.

Hi Mike ! This sounds like a neat little application.

For the MicroLogix 1100, the free version is fine. I think the only thing you lose is online cross-referencing, which isnt' a huge deal in a small controller.

I would probably use one PTO instruction, then load it with different arguments and trigger it differently.

The thing you need to investigate and concentrate on is the fact that it sometimes works, and sometimes doesn't. You need to figure out a way to diagnose this by counting pulses independent of the controller, or by performing some other diagnostic that can tell the difference between the circumstances that make it work and those that don't make it work.

If you ZIP and post your *.RSS file (or at least the part that has to do with the PTO) folks can make recommendations. RSLogix 500 is very widely used by Forum members.

If you need faster execution, use an STI as recommended in the Manual rather than multiple PTOs. The PTO is in Chapter 6.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1763-rm001_-en-p.pdf

Stu....

Thanks for the reply Ken here is the program im trying to use.

Thanks Stu, i need to study this cause im not familiar at all with STI

Sir i have a doubt.. I have MLX 1400 (BXBA) ...I connected +24 VDC to VDC1(group2) and by default i am getting +22VDC in output 2,3,4(group2, FET outputs) even when i am not switching ON the output.... Is there any problem in PLC

aravindh.emerick said:

Sir i have a doubt.. I have MLX 1400 (BXBA) ...I connected +24 VDC to VDC1(group2) and by default i am getting +22VDC in output 2,3,4(group2, FET outputs) even when i am not switching ON the output.... Is there any problem in PLC

Click to expand...

Hello Aravindh
you need to apply 0vdc to the com terminal also