PLC/Modbus RTU mode
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7.2 Addressing I/O extension modules
In PLC/Modbus RTU mode, a wireless network can have a maximum of 99 I/O extension
modules.
Use the white thumbwheel on the I/O extension module to set the I/O-MAP address. You
can find information on addressing extension modules from “Setting the address of the ex-
tension modules via the thumbwheel” on page 80 onwards.
7.3 Watchdog
The Modbus telegram watchdog monitors the connection between the master wireless
module and the controller. It is triggered each time a Modbus telegram is received correctly.
Activate the watchdog using the PSI-CONF software.
• Select the “Network Settings” item under “Individual Settings”. Set a watchdog time be-
tween 200 ms ... 65,000 ms.
.
Figure 7-3 PSI-CONF software: Individual Settings, Network Settings
If the watchdog is triggered, an action will be performed on the I/O output modules. You can
set this behavior in the event of an error using the DIP switches on the front.
– OFF = RESET: Output value is set to 0
– ON = HOLD: Hold last output value
For more detailed information regarding switch setting for the different extension modules,
please refer to Section 3, “Description of I/O extension modules”.
If the watchdog is activated and Modbus communication interrupted, the red ERR LED will
flash on all wireless modules in the network. Depending on the DIP switch settings, the out-
put modules issue the corresponding hold or reset value.
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