GE manual GFK-1541B Programming Modbus/TCP Channel Commands

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Rung # 7: When OPEN_SUCCESS is set it triggers READ_REQ, which enables execution of the BLKMOV, MOVE and COMMREQ functions for the Modbus/TCP Read Commreq. READ_REQ is a one-shot (Positive Transition) coil, activating once when OPEN_SUCCESS transitions from OFF to ON.

Rung # 8: The MOVE WORD function moves a zero to the CRS word referenced in the Command Block (see rung #9). This clears the CRS word. This rung also resets the READ_FLT output coil of the COMMREQ Function Block in rung #10.

Rung # 9: The BLKMV INT functions set up the COMMREQ Command Block contents. When this rung is activated, the constant operands are moved into the memory beginning at the address indicated in the instruction. The constant operands in this example are defined in the Modbus/TCP Read Example in this chapter.

GFK-1541B Chapter 4 Programming Modbus/TCP Channel Commands 4-29