Siemens SIMATIC S7 CP340 Programming Manual page 48

5 MODBUS RTU Protocol communication
Fig. 84: Configure MODBUS Master communication parameter
5. After configuration completes, a prompt will ask you whether you load the
driver before it is saved.
Fig. 85: Dialog box prompting loading driver
6. At this moment, it must be connected to the actual PLC. Click Yes to load
the driver or click Load Drivers. The CPU must be in STOP mode when in
loading.
Fig. 86: Load drivers
After the driver is loaded, STEP7 will prompt "Driver already exists" if you load
it another time. After configuration completes, click
compile the hardware configuration and confirm that it has no error.
CP340/CP341/CP440/CP441 Communication and Programming
Entry-ID: 88867653, V1.0, 02/2014
button to save and
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