Micromaster 420 Profibus module F0070

[bdeuell]

I am experiencing an issue with the profibus modules on micromaster 420 drives. I would bet others are having the same problem so hopefully someone has a good solution or we can develop one together.

We have been getting intermittent F0070 faults on the drives for some time and after trying several things to eliminate the issue believe that we have identified the root cause. We noticed that we were able to create and eliminate the fault condition by applying a couple pounds of force, in tension and compression respectively, to the communication module mounted on the front of the inverter. Pulling on the module would cause the profibus status LED to turn red indicating a loss of communication with the inverter. Pushing on the module would reestablish the connection, this also worked to reestablish drives that randomly faulted on their own.

Upon investigation it appears the clip that retains profibus module to the inverter is not sufficient to maintain the electrical connection between the two devices. The plastic case shows no signs of excessive wear or cracking. This seems to be a design flaw in the plastic enclosures.

I have put some thought into possible solutions but am trying to avoid several things: I would prefer not to modifying the enclosures (i.e. cutting the plastic). I need to be able to easily remove the operator interface (BOP) that attaches to the front of the profibus module.

So my question:
Is anyone else experiencing this issue?
Also, has anyone developed a solution?

 

[JRW]

As long as the profibus module is fully snapped in and no tension on the profibus cable pulling down. It should be good. Is there an encoder module mounted too ?

 

[bdeuell]

Profibus modules are fully snapped in. Even when applying some tension to the profibus module did the clip become disengaged but the electrical connection did fail. The only tension on most of the cables is from the weight of short run to the module next to it.

I am fairly confident that the mechanical clip/enclosure design is the problem. Pushing on the front of the modules causes the naturally occurring faults to go away. I believe that the clip is not holding the module in place securely enough to prevent a loss of electrical connectivity. During operation i suspect vibration and the weight of the modules/cables is enough to break the electrical connection. To test this theory I was able to repeatedly create and eliminate the faults by pushing and pulling on the profibus module. For an industrial environment application I would like to see electrical connections capable of withstanding a couple pounds of force without losing connection.

There is no encoder module.