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CTI 2572 Installation and Operation Guide
124
Command Processing Modes
You can specify how the module command execution is synchronized with the PLC logic by
setting the Command Mode bit in WY4. The Command Mode bit is described in detail later in
this appendix. You can select either coupled mode or uncoupled mode.
Coupled Mode Processing
Coupled Mode provides for tight "handshaking" between the module and the PLC. When the
PLC triggers the command, the module will execute the command only once. The module
will then wait for acknowledgment from the PLC before allowing the command to be
triggered again. Coupled mode is useful for initiating transfers that must be done exactly one
time per PLC event (such as Starting the Network Server).
Uncoupled Mode Processing
Uncoupled Mode does not require a handshaking sequence from the PLC. When Uncoupled
Mode is selected, the module will execute the command continuously as long as the
command trigger is set. Uncoupled mode is useful for providing continuous updates of PLC
data.
Command Processing Procedure
Following is the typical procedure used to initiate a module command:
• Set up the Command Block(s) in V memory using your PLC programming software
• Load the command slot(s) with the address of the Command Block(s).
• Set the applicable command trigger and mode bits in WY4.
• Monitor the status of the command processing using WX2.