Created Date: November 28,2015

Created by: Ridgeline Mach

Not sure, but the MCR command you 're asking about should NEVER be used as a safety to prevent output operation. The only safe MCR, is a Master Control Relay that is hard wired to disable power to your outputs.

What we do, in addition to a hard wired MCR, is have an input on the PLC monitor whether the MCR is energized, or not, through one of the normally open contacts of the MCR.

Created Date: November 30,2015

Created by: OkiePC

If you stop calling a task, the associated logic will no longer run and therefore the bits in the "coil " instructions will no longer alter the values of their bits.

In other words, the outputs will be left in the last state commanded the last time the task was called.

I am not a fan of MCR instructions. I would rather add a single "contact " or XIC instruction to every rung and have them all execute all the time. To disable those outputs, I can turn off that bit. I could understand using MCR type of programming only if you are out of program memory.

I am also an opponent of conditional subroutines in most cases. They have a place for certain types of math, but for normal control situations, I believe in running all the code all the time.

Using conditional routines to controls bits and especially real world outputs can lead to confusion and a convoluted program in the end.

Created Date: November 30,2015

Created by: Ridgeline Mach

If you stop calling a task, the associated logic will no longer run and therefore the bits in the "coil " instructions will no longer alter the values of their bits.

In other words, the outputs will be left in the last state commanded the last time the task was called.

I am not a fan of MCR instructions. I would rather add a single "contact " or XIC instruction to every rung and have them all execute all the time. To disable those outputs, I can turn off that bit. I could understand using MCR type of programming only if you are out of program memory.

I am also an opponent of conditional subroutines in most cases. They have a place for certain types of math, but for normal control situations, I believe in running all the code all the time.

Using conditional routines to controls bits and especially real world outputs can lead to confusion and a convoluted program in the end.

If I had been more complete in my response, I would have said that this is exactly what the input tied to my MCR does. It gives me dual redundancy of stopping a circuit.

Created Date: December 01,2015

Created by: kewakl

If you stop calling a task, the associated logic will no longer run and therefore the bits in the "coil " instructions will no longer alter the values of their bits.

I am also an opponent of conditional subroutines in most cases. They have a place for certain types of math, but for normal control situations, I believe in running all the code all the time.

Using conditional routines to controls bits and especially real world outputs can lead to confusion and a convoluted program in the end.

And, as I have found (at least in earlier versions of P 3 K)

DO NOT PUT COMMS INSTRUCTIONS IN CALLED TASKS!

Created Date: November 27,2015

Created by: christine

Hello! as a new user, am very sure that some of you ever had this problem.

Im tring hard to be able to disable a part of my ladder(outputs ' without all the rest.

So

I try to but my outs in a 'Call Task 'But it appears that when the task is not Call

the outputs are still on ???

Do I have to disable each rung with a NO CaLL contact

Confused

With AB i use a MRC coil is there something close p2-550

HELP

Christine