GE PACSystems RXi User Manual page 197

Chapter 8. Gigabit Ethernet (GbE) Interface Overview and Operation
Rung #6: When ETH_READY is set the CRS word for the Open Modbus TCP Connection
COMMREQ is monitored for a status of 1, indicating that the Open COMMREQ completed
successfully. The CRS word change to 1 sets coil OPEN_SUCCESS.
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 (refer to 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 DATA_INIT_COMM function sets up the COMMREQ Command Block
contents. When this rung is activated, the constant operands are moved into the memory
specified in the DATA_INIT_COMM properties. The constant operands in this example are
defined in the Modbus TCP Read example on page 169.
Rung #10: The COMMREQ function block has the same input parameters has in Rung 5.
The FT output (energizes the READ_FLT coil in this example) is turned ON (set to 1) if there
were problems preventing the delivery of the Command Block to the Ethernet interface. In
this case, the other status indicators are not updated for this COMMREQ.
184 PACSystems* RXi Distributed IO Controller User Manual GFK-2816F