plc.myforum.ro

coco243 · Junior Joined: 01 Aug 2012 Posts: 4

Hy,

I have a situation, if you can help me.

I have something like in the attached picture.

[URL=http://imageshack.us/photo/my-images/89/branchesje.jpg/] Ladder branch control Ladder branch control

Ladder branch control Ladder branch control

[/URL]

At the end of the cycle, M1, M2, M3 are reseted ( goes at OFF status ), they are made ON ( if is the case ) within the cycle time.

The problem is, when the status of M4 goes ON at the end of the cycle and in the same time, M1, M2, M3 are reseted, the program goes at rung 0, and the rung 1 doesn't come to be made. M3 doesn't have time to be maked ON during the program cycle because the programe resets M1,M3 and M3 and the branch 0 it is maked first.

Plese help me to solve this problem without timers.
Thank you very much.

[/img]

mojo · Senior Joined: 01 Oct 2011 Posts: 2404

coco243,
usually the cycle on a plc goes like this:
1. All the inputs are read and store in a temporary memory RAM and when the outputs are setting there are used these values. So if an Input does change during the cycle time it is taken into account on the next cycle.
So in this manner the data for setting outputs are not changing during a PLC cycle.

coco243 · Junior Joined: 01 Aug 2012 Posts: 4

Thank you mojo.
Can you please give me an ideea to find a way to freeze the program at the last readed input, before the outputs starts to be executed? because the cycle is very fast and I can't follow the flow of the program.

Thank you.

mojo · Senior Joined: 01 Oct 2011 Posts: 2404

coco243 · Junior Joined: 01 Aug 2012 Posts: 4

I am speaking generaly. I use TWIDO SUITE, OMRON CX PROGRAMER, how I do to control the speed of the program running? In that way to be able to see the steps and the ways where the program goses.

Thank you.