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We have an application using AB SLC5/05's which are connected via Ethernet.
We need to implement four PID Loops where the PV signal is wired to our 'local' PLC and the CV signal is wired to the 'remote' PLC. I would prefer to wire the CV signals directly from the local PLC to the valves (about 1000'), but my customer is insisting that we perform the PID function in our PLC and pass the CV signals over Ethernet to the remote PLC.
I've told them about the non-deterministic nature, of Ethernet vs. hard wiring and they've told me that its just too expensive to hardwire. My rule of thumb is to never do real-time 'control' via communications, but I just can't seem to convince them that this is the way to go.
Does anyone have any compelling arguments, either way?
We need to implement four PID Loops where the PV signal is wired to our 'local' PLC and the CV signal is wired to the 'remote' PLC. I would prefer to wire the CV signals directly from the local PLC to the valves (about 1000'), but my customer is insisting that we perform the PID function in our PLC and pass the CV signals over Ethernet to the remote PLC.
I've told them about the non-deterministic nature, of Ethernet vs. hard wiring and they've told me that its just too expensive to hardwire. My rule of thumb is to never do real-time 'control' via communications, but I just can't seem to convince them that this is the way to go.
Does anyone have any compelling arguments, either way?