EETC PLC Programming 2

Question 1

In ladder logic, what does a normally closed (NC) contact do when its associated coil is energized?

Accepted Answer

Blocks power (opens)

Answer

A normally closed contact opens (blocks power flow) when its associated coil or bit is energized.

Question 2

Which PLC addressing mode uses a fixed memory location that does not change during program execution?

Accepted Answer

Direct addressing

Answer

Direct addressing specifies a fixed, absolute memory location in the PLC's data table that remains constant throughout execution.

Question 3

What is the primary function of a PLC's accumulator register in arithmetic operations?

Accepted Answer

Holds intermediate results of math operations

Answer

The accumulator is a working register that holds intermediate values during arithmetic, comparison, and data manipulation operations.

Question 4

A TOF (Timer Off-Delay) instruction begins timing when its rung condition:

Accepted Answer

Goes from true to false

Answer

A TOF timer starts its countdown when the rung condition transitions from true to false (de-energized).

Question 5

In Allen-Bradley ControlLogix PLCs, which data type is used to store a 32-bit floating-point value?

Accepted Answer

REAL

Answer

The REAL data type in ControlLogix stores a 32-bit IEEE 754 single-precision floating-point number.

(EETC) Electrical Technician Certification Practice Test