Supply Voltage Status; Fault Behavior; Fieldbus Failure; Internal Bus Fault - WAGO 750 Series Manual

66 • Fieldbus coupler 750-342

Fault behavior

3.1.7.3 Supply voltage status

There are two green LED's in the coupler supply section to display the supply
voltage. The left LED (A) indicates the 24 V supply for the coupler. The right
hand LED (B or C) signals the supply to the field side, i.e. the power jumper
contacts.
LED
A
green
OFF
B or C
green
OFF
3.1.8 Fault behavior

3.1.8.1 Fieldbus failure

A field bus failure is given i. e. when the master cuts-out or the bus cable is
interrupted. 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 the
watchdog-register in the case of fault free communication, and the coupler
answers all following MODBUS TCP/IP requests with the exception code
0x0004 (Slave Device Failure).
More information
For detailed information on the Watchdog register see Chaper "MODBUS
Functions"; "Watchdog (Fieldbus failure)".

3.1.8.2 Internal bus fault

An internal bus fault is created, for example, if an I/O module is removed. If
this fault occurs during operation the output modules behave in the same
manner 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 the
node outputs are correspondingly set.
Meaning
Operating voltage for the system exists.
No operating voltage for the system.
Operating voltage for the power jumper contacts exists.
No operating voltage for the the power jumper
contacts.
Trouble shooting
Check the supply voltage (24V and 0V).
Check the supply voltage (24V and 0V).
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