MC Function on Q CPU

[Andrei Blagaila 4]

If I use at the begging of a POU the MC Nn Mn command do I have to use something at the end of the POU? I want the entire block to work only if certain conditions are True.

Thank you

[niklas 1]

I'm not sure what you are trying to acheive here. Could you specify a bit more? What language do you want to use? Printscreens?

Most functions has a [Function block name]_E type whitch can be used to limit the function by adding conditions Before the EN-signal.

[Andrei Blagaila 4]

Sure. I have a function for the machine that I want to abilitate and disabilitate. If the conditions are true is works, if not it skips the code. I tried with GOEND but if by accident the Latch is switched off while working the outputs freeze ON and it could cause major problems.

[titanspark76 5]

At the end of the section you want to control you need to add a MCR instruction (---ll----SM400---------------[MCR N0]). Everything before the MC instruction and everything after the MCR instruction will scan normally and not be affected by the MC instruction.

[Andrei Blagaila 4]

And if I use the whole POU? Do I need to use MCR? Or is it not needed?

[titanspark76 5]

6 hours ago, Andrei Blagaila said:

And if I use the whole POU? Do I need to use MCR? Or is it not needed?

That should be fine. Also I made mistake on previous post. You cannot place a contact in front of the MCR so your final line should be ----------------------------------[MCR N0]

[Andrei Blagaila 4]

Thanks. I'll leave it without and test on the machine soon. If it works I will leave it like this, if not before the [END] line i will put [MCR N0].

[titanspark76 5]

I misunderstood your question. I think you will have to use the MCR function even if you are using the master control for the whole program. I don't have a PLC to connect to to be sure, but I expect you will receive a PLC error if not. I suppose you could try it without just to see, but I'm certain it will work if you do include include the MCR instruction. Let us know.

[Andrei Blagaila 4]

I loaded it to the CPU and no error lights. Everything is running. I checked to see the next POU and that works even if the functions is disabilitated. I don't have the tool here to test on it but in a couple of weeks I can do that. For the Simulation Stand that has a complete PLC rack and HMI it seems to work.