Diagnostic of Ethernet communications in Unity Pro


Thread Starter


We are using TSX57 2634M Premium PLC with integrated Ethernet port. I configured I/O Scanning feature to get information from other PLCs.

How can I know that Ethernet connections to some PLCs are broken now (i.e., those PLCs are turned off)? Are there any diagnostic bits?

Thanks for your replies.
IntraVue is a package that helps non-network specialists to monitor and troubleshoot IP devices that are connected to an industrial Ethernet application. This software allows you monitor in real time what occurs on your network and pinpoint intermittent communication failures such as device locks-up, disconnection, reconnection, bandtwith issue, duplicate IP and/or MAC addresses...

I think ths package could help you in your case.

Bruno SEON
ARC Informatique
[email protected]
To all,

Have a bit or word constantly changing in in every PLC, the clock seconds works well. Move this data to the read block. Have all other PLCs read this bit or word. If the value is changing, all is good. If the value is the same for multiple read intervals, you have lost communications and all data from the PLC that is down is no longer valid.

This logic is commonly called a watchdog timer.

This will work with any PLC.

Rob Barrese

Fred Loveless

We have diagnostics in our server product but many times we will have customers do a WireShark capture. WireShark reognizes and breaks down the Modbus Ethernet Packet.


Fred Loveless
Kepware Technologies
Support Manager
In Unity Pro do a search for IODDT (Datatype) which should provide you access to the information that you seek. In the IODDT for the Ethernet I/O Scanner you should have a BOOL that corresponds to each entry in the I/O Scanner Table. If the I/O Scanner canot communicte to the target device then this bit will change state.