Fieldbus Coupler 750-341 • 87Fault behaviorWAGO-I/O-SYSTEM 750ETHERNET TCP/IP3.1.10 Fault behavior3.1.10.1 Fieldbus failureA field bus failure is given i. e. when the master cuts-out or the bus cable isinterrupted. A fault in the master can also lead to a fieldbus failure.A field bus failure is indicated when the red "ERROR"-LED is illuminated.If the watchdog is activated, the fieldbus coupler firmware evaluates thewatchdog-register in the case of fault free communication, and the coupleranswers all following MODBUS TCP/IP requests with the exception code0x0004 (Slave Device Failure).More informationFor detailed information on the Watchdog register see Chapter "MODBUSFunctions"; "Watchdog (Fieldbus failure)".3.1.10.2 Internal bus faultAn internal bus fault is created, for example, if an I/O module is removed. Ifthis fault occurs during operation the output modules behave in the samemanner as an I/O module stop. The "I/O" LED blinks red.The coupler generates a fault message (fault code and fault argument).After clearing the internal bus fault, restart the coupler by cycling the power.The coupler starts up. The transfer of the process data is then resumed and thenode outputs are correspondingly set.
