From the course: PLC Sequencer Logic

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Sequencer compare instruction (SQC)

Sequencer compare instruction (SQC) - Ladder Logic Tutorial

From the course: PLC Sequencer Logic

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Sequencer compare instruction (SQC)

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- [Instructor] Sequencer Compare Instruction is an instruction that compares input data with a reference. It is very similar to the Sequencer Output Instruction, but instead of a destination parameter, this instruction has a source parameter. Everything else is the same: file, mask, control, length, and position. It is an output instruction, so it is placed on the right-hand side of the rung. It increments the position parameter with false-to-true run transition very similar to the Sequencer Output Instruction. The Sequencer Compare Instruction can be used as a diagnostic tool. For example, to determine if a machine has the correct signal with values in a register to start a production run. So it is used to compare the status of a machine's input devices, on or off, with what is required for a normal operation.

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