crevans2025
Member
What is the benefit of using external relays when you wire a DI signal to a PLC I/O card. For example, why would I install an external relay in my flow switch circuit.
I design with forcable DI relays when the operators must be able to run in case of a broken sensor or other invalid state. Then it is uncomplicated to generate a good signal.
Isolation..
Keep whatever happens in the outside world (anything outside the PLC cabinet) away from your PLC.