Practice Test Geeks(EETC) Electrical Technician Certification Practice Test
← All EETC Flashcard Decks

PLC Programming Flashcards

7 cards from real EETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 PLC Programming flashcards as text

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

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

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

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

    Answer: Reaches 10 or greater

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

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

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

    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.

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

    Answer: Loads a value into the current result (accumulator)

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

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

    Answer: The rate of change of the error signal

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

  6. What is a 'latch' (OTL) and 'unlatch' (OTU) coil pair used for in ladder logic?

    Answer: To create a retentive output that holds its state independently of rung conditions

    OTL sets a bit retentively (it stays on even if the rung goes false), and OTU clears it; together they form a retentive memory function.

  7. In a PLC network using PROFIBUS DP, what is the role of the 'master' device?

    Answer: It initiates all communications and polls slave devices for I/O data

    In PROFIBUS DP, the master device controls bus access, cyclically polls each slave, and exchanges I/O data with them in a token-passing scheme.