Practice Test Geeks(ITMC) Industrial Technology Maintenance Certification Practice Test
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PLC Operations Flashcards

7 cards from real ITMC 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 Operations flashcards as text

  1. In a PLC safety system context, what does 'SIL' stand for?

    Answer: Safety Integrity Level

    SIL (Safety Integrity Level) is a measure of safety system performance defined in IEC 61508, ranging from SIL 1 (lowest) to SIL 4 (highest).

  2. When a PLC program needs to execute a specific subroutine only under certain conditions, which instruction is typically used to call that subroutine?

    Answer: JSR (Jump to Subroutine)

    JSR (Jump to Subroutine) transfers program execution to a subroutine file/routine and returns via a RET instruction when complete.

  3. What is the primary advantage of using DeviceNet over traditional hardwired I/O in an industrial PLC system?

    Answer: Lower installation cost with reduced wiring via a single network cable to multiple devices

    DeviceNet reduces installation wiring by connecting multiple devices (sensors, actuators, drives) on a single network trunk cable.

  4. In ladder logic, if two XIC contacts are placed in SERIES on the same rung, the output coil energizes when:

    Answer: Both contacts are simultaneously TRUE (AND logic)

    Series contacts implement AND logic—current flows through the rung only when all series contacts are closed (TRUE).

  5. A technician notices a PLC analog input reading is stable but offset from the true process value by a fixed amount. The most likely cause is:

    Answer: Incorrect scaling or zero/span calibration in the PLC program or module

    A consistent fixed offset typically indicates a scaling or calibration error rather than noise (which causes erratic readings) or hardware failure.

  6. Which PLC operating mode allows the programmer to make online edits to the ladder logic while the machine continues to run?

    Answer: RUN mode with online edit capability

    Most modern PLCs support online editing in RUN mode, allowing logic changes to be tested and accepted without stopping the process.

  7. In PLC I/O terminology, what does 'sinking' input module mean?

    Answer: The module receives (sinks) current from the field device—the common is connected to the negative rail

    A sinking input module has a common negative (–) terminal; field devices supply current into the input terminal, which the module sinks to common.