EETC PLC Programming 5

Question 1

In PLC programming, what is 'dead-band' as it applies to analog process control?

Accepted Answer

A range around a setpoint within which no corrective action is taken

Answer

Dead-band defines a neutral zone around the setpoint where the controller ignores small deviations to prevent excessive cycling of the output.

Question 2

A PLC program uses a CTU (Count Up) instruction with a preset of 10. The output bit (DN) energizes when the accumulated count:

Accepted Answer

Reaches 10 or greater

Answer

The CTU Done bit energizes when the accumulated value equals or exceeds the preset value.

Question 3

What is the role of a watchdog timer in a PLC system?

Accepted Answer

Monitors scan time and faults the PLC if a scan exceeds the maximum allowed time

Answer

The watchdog timer automatically faults the PLC if a single program scan takes longer than the configured maximum time, indicating a program loop or CPU hang.

Question 4

In Instruction List (IL) programming (IEC 61131-3), the operator 'LD' performs what action?

Accepted Answer

Loads a value into the current result (accumulator)

Answer

The LD (Load) operator loads the specified operand value into the current result register, starting or resetting an expression.

Question 5

When configuring a PID instruction in a PLC, the 'derivative' term (D) primarily responds to:

Accepted Answer

The rate of change of the error signal

Answer

The derivative term responds to how quickly the error is changing, damping the controller response to prevent overshoot.

(EETC) Electrical Technician Certification Practice Test

(EETC) Electrical Technician Certification Practice Test

EETC PLC Programming 5