AutoQuiz: What are the Basic Components of a Programmable Logic Controller or PLC?

AutoQuiz is edited by Joel Don, ISA's social media community manager.

Today's automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for information about the CCST program. This question is from the Level III study guide, Domain 2, Loop checking. Level III represents a professional who has a 13-year total of education, training, and/or experience.

All of the following are basic components of a programmable logic controller system, EXCEPT:

a) processor
b) I/O system
c) power supply
d) video monitor
e) none of the above

    A programmable logic controller (PLC) has a microprocessor, and it controls industrial processes. It communicates with other process control components through data links, handles simple switching tasks, PID (proportional-integral-derivative) control, complex data manipulation, arithmetic operations, timing, process, and machine control-all without a video monitor. Engineers program it and leave it alone.

The correct answer is D.