Pepperl+Fuchs LB Series Manual page 54

LB Remote I/O System
Troubleshooting
Redundancy Faults
Fault
Continuous redundancy
switchover
No redundancy
switchover when a com
unit is removed
I/O modules are
continuously changing the
data
Signal Faults
Fault
Faulty signal
All signals for a station are
faulty
The output module
switches off
Input module sporadically
delivers no measured
values
Measured values
occasionally incorrect
I/O module reported to be
faulty
54
Remedy
Check that the correct type of redundancy is selected (media redundancy or

application redundancy).
In the configuration software, check whether the master read cycle and the

com unit watchdog are coordinated with one another.
Check that the process control system is set to the correct type of redundancy.

Check that redundancy has been configured at the com unit.

Check that there is an electrical connection between the two com units. If not,

establish a connection.
Check whether one of the com units has not been configured for redundancy

mode. If this is the case, both com units actively try to access the I/O modules
and interfere with one another.
Remedy
Check whether the I/O module is in simulation mode or whether it is working

with substitute values.
Check if there is a short circuit or lead breakage within the circuit.

Check that the field devices and sensors are working properly.

Check the communication path to the I/O module.

If necessary, replace the I/O module.

Check that the power supply is working properly.

Check the bus connection.

Check the bus communication using a bus monitor.

Communication with the com unit is interrupted.
Check that the I/O module is plugged into the backplane properly.

If necessary, switch off the status bits for analog outputs in the configuration

software.
Communication with the com unit is interrupted.
Check that the I/O module is plugged into the backplane properly.

Check whether the measured value is being distorted by external influences.

Check that the shielding is intact.

Check that the correct I/O module is plugged in.

Check that the green LED on the I/O module is lit and that the I/O module is

correctly plugged in.