SeanLee said:
The reason for 2 different *******lers is the 5/03 is existing with no room in cabinet for expansion. The 5/04 is an extantion of the machine and used for separte machine also.
So, if I understand correctly:
The SLC5/03 controls part of one machine.
The SLC5/04 controls the rest of the machine, and also another machine.
So the reason for requirement for exchanging data between the two CPUs, is for interlocks that are really internal to one machine ?
I hate to say this, but it was a wrong decision to let one machine be controlled by 2 CPUs. You are now running into problems because of that.
I would have expanded the old system by attaching the expansion i/o to the original CPU via RIO or Devicenet.
I would have let the other machine be controlled by its own CPU.
It will take some expense to put it right. But I would bite the bullet and get over it.
Notice that despite you get some expenses you also save all the communications parts and programming for getting the two 'brain-halves' to speak together.