13 PROFIBUS GATEWAY MODULE (PGM) TROUBLESHOOTING
13.4 Fixing common problems
This section identifies some common problems and describes how you might fix them.
Loss of communication with the devices when a switchover is initiated
Loss of connection to some of the field network slave devices
Diagnostic Check Slave devices that are not communicating with the PGM have their status as "Bad."
Loss of communication with the slave devices when a switchover is initiated.
Probable PROFIBUS master configuration (bus parameters) errors. For example, Watchdog
Control Time and Data Control Time are not configured properly.
Modify the Watchdog Control Time and data control time based on the Baud Rate.
The following table lists the various Baud Rate and the recommended Watchdog Control
Time and the Data Control Time.
These values may differ based on the number of slave devices configured in the
For the slave devices that have DP-V1 enabled, the Watchdog Control Time and
the Data Control Time must be three times longer than the actual time when DP-
V1 is disabled.
By default, the ET200M devices have DP-V1 enabled.
Network or power supply wiring problems in the field network.
Open the Protocol Block detail displays to check the slave devices that are not communicating with
Obtain the field network wiring diagram and slave device power supply schematics.
Fix the problematic network wiring or power supply wiring manually.
Otherwise, go to Cause 2.
Slave devices are not configured properly.
Check for the slave device configurations and correct the configurations, if any.
Otherwise, go to Cause 3.
Slave devices are broken.
Replace the broken slave devices one by one.
Watchdog Control Time
Data Control Time