Devicenet cable in a energy chain .Randomly loosing Devicenet I/O

[Cydog]

Good Morning ,

We have Devicenet cable running through a energy chain . We are loosing random Devicenet I/ O , causing our transfer car to stop in its travels .

We don’t get any errors or fault codes on our Devicenet scanner .

Any thoughts and have you seen this before ?

Thanks so much .

 

[cncsparky]

We have one system still on DN. Whenever we start having intermittent issues with different nodes, we go through every connector and tighten up all 5 DN connections. Every few years, usually straightens out the problems.

 

[Jim3846]

Is this random or consistent fault?
Random is usually attributed to noise.
If its a consistent fault then its usually a media problem (cable nicked, loose connection, etc...)

 

[Cydog]

It is not any faults . Just loosing data , such as drive enable signals , etc. With the
Drive being disabled in spurts , it causes the motors to jerk .

 

[Ken Roach]

What kind of DeviceNet scanner are you using, and what kind of I/O or drives/servos are attached to it ?

Have you put any "trap logic" into the PLC controller to catch any errors that are only of short duration and reset themselves ?

Is the cable in the e-chain a continuous flex-rated cable ? Are there any connectors along the flexing section, or near enough that they could have force applied to them by the flexing section ?

It is very unlikely, bordering on impossible, that your drive is "randomly missing DeviceNet signals" without declaring a timeout or fault either on the drive or on the PLC.

But it is possible, maybe probable, that if the DeviceNet media and installation has connectivity problems that previous engineers have disabled or suppressed fault functions, so that they don't appear and only the practical effects of a failed network connection show themselves.