Is there a good way to show PLC control logic, both analog and discrete, on a PFD? How would one show manually-inputted PLC parameters (e.g., a manually-inputted flow limit)?
You cannot squeeze it all onto a PFD, create separate diagrams and put a cross reference to them on the PFD.
Or use ControlDraw and add the PLC logic as linked diagrams.
PLC/DCS Logic is not typically shown on a PFD. The PFD is used more for presenting flows, temperatures, volumes, pressures of the process at a higher level.
The P&IDs are what should contain the PLC/DCS logic. Take a look at ISA 5.1 for reference on how to show the PLC logic.
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This is normally the space where people post something insightful.
You cannot squeeze it all onto a P&ID either, create separate diagrams and put a cross reference to them on the P&ID.
Or use ControlDraw and add the PLC logic as linked diagrams.