Technical data

74 • Feldbus Coupler 750-344 / -345
Fault behavior
WAGO-I/O-SYSTEM 750
INTERBUS
3.1.8 Fault behavior
3.1.8.1 Loss of fieldbus
A fieldbus failure is indicated, for example, if the master is switched off or if
the bus cable is interrupted. An error at the master can also result in a fieldbus
failure.
On a failure of the fieldbus, the green BA LED goes out and the coupler de-
activates all outputs.
Substitute value Value (bit orientated)
Digital Output Modules
Value (byte orientated)
Analog Output Modules
Minimum value 0 0 and 4 mA, -10 and 0 V
Stop internal bus Response determined by the I/O module
All values in the output process image are set to 0 by the coupler. With I/O
modules that have a byte orientated data width (e.g. pulse width module), the
substitute value is determined using the value range.
As soon as the fieldbus is reactivated, the process data is transmitted again and
the outputs of the node are set accordingly.
3.1.8.2 Internal bus failure
An internal bus failure occurs, for example, if a bus m
odule is removed. If the
error occurs during operation, the output modules operate as they do during an
internal bus stop: The input process image is reset and the bus coupler reports
a periphery error to the master.
The I/O LED flashes red. The bus coupler generates a detailed diagnostic
message.
After the internal bus error has been eliminated, the coupler is restarted
automatically. The process data is transmitted again and the outputs of the
node are set accordingly.