Industrial Ethernet Problem after Holiday

After every prolonged 'down' period we have major issues with comms on 7th axis Robots (this has happened on both the ABB and Fanuc Robots).

- Comms is generally from a switch in the Robot cabinet,
- through a connector stand at the base of the 7th axis track,
- through the track into another connector at the base of the Robot,
- through the Robot into another connector at the top of the Robot
- then into the communication device (be it a festo I/O module or Armour block I/O module).

It is designed like this to give several points of sacrificial cable for quick repair/replacement. The cable is Leoni High flex cable (part number F07249-03-04). Cable runs can be quite long in some cases (10 + meters if that is a factor?). In every case the fix is to replace one of the sacrificial cables.

Could I ask the question as to why this happens? And if there is anything we can do to stop it happening (besides continuous running)?

Any help would be greatly appreciated, thank you.
Unfortunatley this kind of wear and tear should be expected, I worked on Durr Robots for nearly 10 years and have experienced similar problems.

Are you 100% sure it is the cable that is failing? If it happens after long periods on non-running maybe the communication is being disturbed and not recovering.

Have you tested the 'suspected' broken cable off the robot? (I.e., tested for link voltage and check for packet losses etc).
Yes, most times the cables are belled out as okay - but I don't think this is a good enough test. My thinking is the properties of the cable may somehow change with the changing temperatures of continuous work and prolonged stoppage.

I have asked to get the actual resistance checked on a failed cable compared to a new cable to see if there is a marked difference and maybe check a complete working circuit (maybe a slight change of resistance is causing the issue).

In the main, the network is robust enough to recover itself so I don't believe its that. The only other thing I can think of is to see if there is a repeater/extender I can mount on the Robot?

How do you resolve the comm issue?

Also, aside from checking the continuity, bell, or light checking the pairs, there is also a meter than can make sure you are getting the performance out of the run, making sure it is compliant with TIA standards. Fluke has options for troubleshooting and validation/certification of network segments. Per the previous comments something could change environmentally over the holiday that impacts the connections. Each segment would have to be assessed to determine if it meets the requirements for the environment or if there is a shorter PM interval.

Over that kind of time, I know older PLCs will time out, PLC5 Half Duplex for an example would need to be restarted after a outage at the switch end.

Would be interested to know more.