Chapter 16 Sqc- Sequencer Compare; Chapter 16 Sequencer Instructions Sqc- Sequencer Compare - Allen-Bradley MicroLogix 1400 Instruction Manual

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Sequencer Instructions

SQC- Sequencer

Sequencer Compare

Publication 1766-RM001A-EN-P - October 2008

Instruction Type: output

Execution Time for the SQC Instruction

MicroLogix 1400

On a false-to-true rung transition, the SQC instruction is used to compare

masked source words or long words with the masked value at a reference

address (the sequencer file) for the control of sequential machine

When the status of all non-masked bits in the source word match those of

the corresponding reference word, the instruction sets the found bit (FD)

in the control word. Otherwise, the found bit (FD) is cleared.

The bits mask data when reset (0) and pass data when set (1).

The mask can be fixed or variable. If you enter a hexadecimal code, it is

fixed. If you enter an element address or a file address (direct or indirect)

for changing the mask with each step, it is variable.

When the rung goes from false-to-true, the instruction increments to the

next step (word) in the sequencer file. Data stored there is transferred

through a mask and compared against the source for equality. While the

rung remains true, the source is compared against the reference data for

every scan. If equal, the FD bit is set in the SQCs control counter.

Applications of the SQC instruction include machine diagnostics.

When Rung Is:

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