tborycki
Member
Hi all,
I'm trying to understand what, if any, break/delay in the logic scan occurs when using a COP instruction in a SLC500 program.
I have the following instructions executing in my logic (in sequential rungs):
COP #M1:23.0 #N96:0 100
COP #M1:23.60 #N7:170 1
(Reading data from a Prosoft MVI46-MNET module, but I'm assuming this is not important to the question at hand)
Later on in the logic (same scan), I check to see if N96:60 is equal to N7:170. Occasionally they are not the same. The data I am reading back in the M1:23 file does change occasionally as modbus commands execute, but I would have thought that since the COP instructions are occurring immediately after one another the data would always be the same unless some external logic is overwriting it (which does not appear to be happening).
So, the heart of my question: Do COP instructions execute completely (i.e. all source registers copied to the destination registers) before the next rung is executed, or does it run independantly of logic scan?
Thanks,
Trevor
I'm trying to understand what, if any, break/delay in the logic scan occurs when using a COP instruction in a SLC500 program.
I have the following instructions executing in my logic (in sequential rungs):
COP #M1:23.0 #N96:0 100
COP #M1:23.60 #N7:170 1
(Reading data from a Prosoft MVI46-MNET module, but I'm assuming this is not important to the question at hand)
Later on in the logic (same scan), I check to see if N96:60 is equal to N7:170. Occasionally they are not the same. The data I am reading back in the M1:23 file does change occasionally as modbus commands execute, but I would have thought that since the COP instructions are occurring immediately after one another the data would always be the same unless some external logic is overwriting it (which does not appear to be happening).
So, the heart of my question: Do COP instructions execute completely (i.e. all source registers copied to the destination registers) before the next rung is executed, or does it run independantly of logic scan?
Thanks,
Trevor