What is auto mode in a PID controller?

Multiple Choice Questions Automation MCQ
1

Question:

What is auto mode in a PID controller?

Options:

A) PID controls output
B) Holds last value
C) SP follows PV
D) Operator sets output

View Answer

:white_check_mark: Correct Answer: A) PID controls output

:magnifying_glass_tilted_right: Detailed Explanation

In auto (automatic) mode, the PID algorithm actively controls the output based on error:

Error = SP - PV

The controller:

  1. Continuously compares SP and PV
  2. Calculates P, I, and D contributions
  3. Adjusts the output automatically

This allows the loop to self-correct disturbances and maintain the setpoint.

:cross_mark: Why Other Options Are Incorrect

B) Holds last value
That behavior is typical during output hold or certain manual transitions, not true auto control.

C) SP follows PV
That describes setpoint tracking used for bumpless transfer, not auto mode operation.

D) Operator sets output
That defines manual mode.

:fire: Quick Comparison

Mode Who Controls Output?
Manual Operator
Auto PID algorithm