Power Flex DC Drives With 20-Comm-E

[lccllc 0]

Ok I have tried to get this problem fixed by my self for long enuff, and AB is no help. I have a app with four Power Flex DC Drives and am having a problem with a DPI Port Five Comm Fault. The port is the port I have the ethernet adapter in. I have now set the connection time to 300 MS and still have the fault happen a couple of times a day. The drives are not more than 10 feet from the switch and the plc, the wire is shielded and grounded at one end. Other projects I have done have used Power flex drives with the same setup and the connection has been set down to 10 ms not problems. Can some one give me any thoughts and help on this, could it be a issue with the drive, I have already had firmware problems with these drives.

[Ken Roach 194]

Firmware is pretty low on my list of suspects when you get a comm failure on a drive. Noise and cabling always top the list. A communication failure can happen either between the controller and the 20-COMM-E (on the Ethernet), or between the 20-COMM-E and the drive (the DPI ribbon cable). Actual network failures show up as "7x" error codes and DPI failures show up as "8x" error codes. "x" is the DPI port number, which is usually DPI Port 5 for internal communication modules. The first thing I'd check is the embedded web page on the controller (1756-ENBT for a ControlLogix). On the page that shows the I/O connections it will show the number of Missed Packets. If that number is increasing, you have a media problem somewhere. System questions that Tech Support would ask: What kind of controller ? (CompactLogix, ControlLogix, etc) and what kind of Ethernet module are you using ? How many drives on this network ? Any other I/O devices on the network ? Do they every have communication failures ? What is the fault code on the drive ? What do you do to reset the drive ? Do all the drives fault at once or only one ? What kind of Ethernet switch are you using (make and model) ? Are multicast management features enabled on the switch ? Have they been tested and verified ? What is the CPU Utilization of the Ethernet interface module on the controller ? How many packets/second of scheduled data is it handling ? If this is a ControlLogix 1756 system, you also need to check all the hardware against the 2007 "Atmel issue" service advisory to eliminate the backplane bridge chips as a source of communication connection failures.

[lccllc 0]

Thanks ken I will Check this tomorrow when at work. Thanks again for the help

[paulengr 44]

I would also recommend checking your grounding carefully. One of the screws in the 4 mounting screws for the 20-COMM-E card is NOT optional. If you have electricians that don't put in all the screws or tighten them down properly, that may be where your problem is at. It's an easy thing to miss. As to the communication problems, this sounds most likely. But I'd check all of the drives. If that doesn't work, then download a copy of "wire shark", set up port mirroring on a spare port, and use your laptop as a packet sniffer. If you don't have a managed switch and can't afford one, you can also plug a hub (a real hub, not a switch) in between the drive and the switch. Then plug your laptop into the hub. The hub will duplicate all packets on all ports allowing you to sniff packets. This is also the only time I would ever recommend using a hub.

[lccllc 0]

Thanks guys, by the way it is a Control Logix platform, I had one of the guy's at work that night get on line with the Comm card's web page, of the PLC and the missed packets were going up. I have not had time to further look at the problem, but as soon as I can I look into a possible wiring, or grounding problem. Paul thanks for th einfo on "wire shark" I will try this too, did not know there was app for such things.