PLCs are ruggedized computers designed for industrial environments. They operate by scanning inputs, executing a user-programmed logic (ladder logic or function blocks), and updating outputs cyclically. Bolton emphasizes the architecture of PLCs and their role in replacing hard-wired relay logic.
frequency response, transfer functions, and closed-loop feedback Instrumentacion Y Control Industrial Bolton 11.pdf
How different process variables are measured and the principles behind various types of sensors and transmitters. Instrumentacion Y Control Industrial Bolton 11.pdf