From the course: PLC Program Flow and Control Instructions

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Difference between JMP and MCR

Difference between JMP and MCR - Ladder Logic Tutorial

From the course: PLC Program Flow and Control Instructions

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Difference between JMP and MCR

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- [Instructor] The four word jump and label Instructions are similar to an MCR Instruction in that both instructions skip over a block of PLC ladder logic program. The main difference between the two is in how the outputs are handled when the instructions are executed. When a jump instruction is used, the PLC skips all the rungs between Jump Instruction and its associated Label Instruction. And the rungs will not be scanned by the processor. The MCR instruction sets all non-retentive outputs to the false state. And keeps the retentive outputs in their loss states. You should never jump into MCR reset zone. If you do instructions that are programmed within the MCR zone starting at the Label Instruction and ending of the end MCR Instruction will always be evaluated as though the MCR zone is true regardless of the state of the start MCR Instruction.

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