CompactLogix with dcs880 comms problems

[mshelton]

I’m in the process of starting up a piece of equipment. I have a 1769-l33er processor with a dcs880 master-follower pair of drives. I’m communicating over Ethernet/ip. The drives have fena-21 communication modules on them. When I power down the follower drive and power it back up, communication fails to re-establish. The plc code is: (Code 16#000c) Service Request Error: Invalid mode or state for service request. if I put the follower drive into local mode, the communication re-establishes, and stays active if I put it back into remote mode. The same problem doesn’t seem to affect the master. If I power the drive down while in local mode, it will communicate after powering the unit back up.

Any thoughts?

[Ken Roach]

Interesting ! DCS880 is an ABB DC variable speed drive, correct ?

What exactly puts the drive into "Local" or "Remote" mode, and what exactly do those mean ?

My guess is that "local" gets the start/stop/reference from a keypad or discrete I/O, but the "remote" gets them over the network. Is Local/Remote a keypad switch or a physical input ?

How do the drives accomplish their master/follower feature ? Do they have analog connections, or is it supposed to be done by the PLC, or is there a specialty inter-drive link used by the DCS880s ?

The same behavior does not happen to the master drive, correct ?

[mshelton]

Yes, a dcs880 is a dc drive. Either the keypad or the configuration software can put the drive in local. The drive can be run from the key pad or software respectively in local.

It a copper communications protocol I believe can hi and lo, but I’m not sure

Correct the same behavior doesn’t happen on the master. I don’t remember this problem earlier in the start up. I just seems to have cropped up in the last day or so. Hard to say as I don’t make a habit of turning the drive off if I don’t have to