Programmable Logic Controller

Written by Jerry Ratzlaff. Posted in Instrumentation

There are four primary types of signals that the programmable logic controller generates. On a P&ID, when referencing the type of signal for a particular instrument or installation, it should be in reference to the PLC. The types of signals are analog output (AO), analog input (AI), discrete output (DO), and Discrete Input (DI).

  • Abbreviated as PLC