This fault / information is displayed when the watchdog timer in the PLC detected a disruption of communications with the HMI.

Normally this signal will only be displayed for a short time period when a connection is first established by the HMI program.  Since the PLC creates this signal it will only be displayed if the problem is intermittent.  A complete signal failure will diagnosed by a different fault since the HMI will not receive any signals from the PLC for that case.

Possible Causes:
1) System has been initialized after a power up, or restart of the HMI or 2) Ethernet system is experience disruptions on communications.

1) Check Ethernet hardware to insure no cables are damaged.
2) Restart HMI and/or PLC to remove any possible controller internal failure.
3) Check and replace any damaged components - PC (networking card), Ethernet Switch, PLC Ethernet module, etc