A-B CLX5k -Kinetix 6000 Sercos Read

[RoTaTech]

We have 8 Kinetex 6000 2094 drives and A-B motors on one machine, and the vendor has written a routine to display the motor temperature.

For some reason, when the plant ambient temperature is perhaps 18C or so (below 20C for sure), several of the motors will alternate their display temp between 20C, and 32000 or 32001C.

I figure it's a max scaling or data conversion between the motor/drive/sercos/PLC, but cannot (yet) find any data on HOW the motor reads and reports its temperature, nor how sercos translates that across. Attached is a clip of the MSG READ which gathers the temp. I have as yet found no info on how a P-1-302 is structured.

Can anyone enlighten me on this?

 

[robertmee]

Never tried to read IDN parameters, but I believe many of them are of type SINT, not INT. You might try changing the tag/type to SINT. Seems like a sign bit issue.

 

[RoTaTech]

Thanks Robert, but Rockwell's sample code to do this shows an INT read.

After a lengthy chat with two of their techs, I have been told that a) it's not reliable in the first place, and b) it's likely:

For your system, either that data channel is corrupt, the wiring to and from the drive/motor or the motor encoder itself. So you might have to do some component swap to check that temperature swing out.

RT

 

[Ken Roach]

It does sound like a byte swap or sign bit issue.

Are the values exactly "18" and 30001, or is the value in tenths of a degree C ?

The easy fix is to just use a LIM instruction so that the only reported values are those in the reasonable range.

 

[RoTaTech]

Yes Ken, the values are exactly 32001 or 32000. What I have read is the drive sends out Temp*10.

That's what I have done; I just put a LEQ 200 in there to filter out the garbage values, but it piques my interest to figure out the Why of things.

RT