Intermittent & stubborn issue with Sercos network

I'm pulling my hair out trying to determien what's causing intermittent dropping of a small 4-node Sercos network in one of our filling machines. The filler manufacturer has, so far, been unable to solve the issue so I'm hoping someone on this forum can point me in the right direction.

Trying to itemize all the things I've tried would take hours, so I'll be pretty general.

The four Ultra3000 drives (2089-DSD-020-SE) are connected with fiber to a 1756-M08SE Sercos module. The module is in the last slot of a 13-slot Contrologix rack.

Some of the most recent things we tried were:

• Every fiber cable has been changed
• The direction of the fiber network has been reversed and changed back
• Every Ultra3000 drive has been changed with a new replacement
• A new 1756-M08SE was installed
• A new 1756-A13 rack was installed
• A new 1756-L61 CPU was installed
• A new power supply has been installed
• Every possible combination of firmware for the CPU and Sercos module. Current CPU Rev = 17.5 and Sercos Rev = 18.5. Like I said, firmware versions don't seem to make any difference
• Cycle times of 0.5, 1 and 2ms were tried
• High and low transmit power was tried
• I didn't adjust "transition to phase" - it's set to "4"
• A copy of a "similar" program from another filler of the same generation was provided by the manufacturer. The logic matches, but a lot of the settings under Motion Groups - AxisMotionGroup are different. I tried the settings from the new program, but get approximately the same results.

The filler has been giving us issues for years, but usually would only act up once or twice a month. now, it's acting up every few minutes, although we did operate the whole day last Friday without issue.

Any suggestions? We've easily spend $20K+ on parts, not to mention untold hours of troubleshooting and machine downtime.

I can send a copy of the most recent version of the Logix5000 program to anyone who would be willing to take a look.If you're looking for work and have confidence in your ability to solve the issue, PM me and we'll arrange a contract.

Have you tried to move the Sercos card to one of the first few slots in the rack?

I have tried moving the module into both empty slots. Didnt help.

rguimond said:

Any suggestions? We've easily spend $20K+ on parts, not to mention untold hours of troubleshooting and machine downtime.

Click to expand...

I would call Rockwell and get one of their Motion Service Engineers on site, if you have spent that much time and money already then it must be worth getting them in for a day.

Explain to Rockwell Tech Support exactly what you have tried already so that the engineer knows what to expect and can do his homework before he arrives on site.

What do the error logs say?

Recheck the firmware and get them all to the same rev (ie 17 or 18)

especially the Ultra 3000 - make sure its the latest revision

Also please post the error code (if one) that occurs on the drive and is it the same drive?

what is the cabinet temperature? Had an ultra that would misbehave intermittently and ended up installing an air con and the problem went away.


there is a version compatibility matrix on the rockwell site - I don't seem to be able to find it at the moment

When you say you checked the cycle times, does the ultra have the dip switch setting on the drive as well as the setting in the software. I have only done the 6200 drives.

Did you check to make sure the drive is properly grounded per specs.

Upgrading to version 20 along with firmware updates may be worth trying.

Solved!

After much troubleshooting, it was determined that the 2090-U3CBB-DM12 break-out board connecting the servo to the Ultra-3000 was the issue. No one thought this unit was anything other than a 90-degree cable connector. Turns out there's a diode, a resistor, a capacitor and a 24VDC - 5VDC converter in the housing. We haven't started a forensic analysis to determine what component failed, but my guess is that the resistor was overheating, based on slight discoloration at one end.

Thanks for all your suggestions.

rguimond said:

After much troubleshooting, it was determined that the 2090-U3CBB-DM12 break-out board connecting the servo to the Ultra-3000 was the issue. No one thought this unit was anything other than a 90-degree cable connector. Turns out there's a diode, a resistor, a capacitor and a 24VDC - 5VDC converter in the housing. We haven't started a forensic analysis to determine what component failed, but my guess is that the resistor was overheating, based on slight discoloration at one end.

Thanks for all your suggestions.

Click to expand...

thank you for posting your solution
I have not seen that one but will keep it in my bag of things that may happen