ControlLogix 5000 EtherNet/IP Mystery
ControlLogix 5000 EtherNet/IP Mystery
(OP)
We have an Allen Bradley ControlLogix 5000 system operating for about eight months. It controls a stamping machine. anyway, it broke down on December 28, 2009. Then suddenly started to work from the next day morning. No surprise that it has broken down again two days ago, after running for about 12 days. I'll explain the symptom of the breakdown. But let me describe a strange thing that I noticed here.
Description of the PLC.
1. Power supply
2. CPU ControlLogix 5555 (slot 0, catalog 1756-L55 A)
3. 2-Axis servo controller (slot 1, catalog 1756-M02AE/A)
4. DC Input card (slot 5, catalog 1756-IB32)
5. DC Output card (slot 7, catalog 1756-OB32)
6. EtherNet/IP communication bridge (slot 8, catalog 1756-ENBT A)
7. DeviceNet card (slot 9, catalog 1756-DNB)
Now, from my limited IT knowledge I think the EtherNet/IP bridge should connect the PLC system with some external IP network. But strangely enough, there is absolutely no connection to this module, except the backplane.
There is an HMI connection in the system, but that is on the DeviceNet card, and through a CANbus cable.
Does anyone know why the EtherNet/IP card is there? Can it have any function I'm missing?
Now about the breakdown. The symptoms are . . .
- CPU starts up. "OK" and "RUN" LEDS glow right. "I/O" LED blinks.
- Servo controller - "OK" LED blinks. "FDBK" and "DRIVE" LEDs for both channels remain off.
- DC Input card - "OK" blinks.
- DC Output card - "OK" blinks.
- EtherNet/IP card - "OK" on. "NET" blinks. "Link" off. Scrolling display says "Link Lost".
- DeviceNet card - "OK" blinks, "I/O" blinks, "MOD/NET" on.
- HMI starts up, cannot read any param from the PLC
I need to fix the breakdown and get the production line back immediately. But I cannot find any clue. Is it possible that the EtherNet/IP card is looking for a link and finding none, it is stopping the CPU?
We have two other machines like this, and both have similar Ethernet card with NO external connections. None of them are reporting "Link Lost".
Thanks much for your time. I really need some insight into this mystery. Best regards.
Description of the PLC.
1. Power supply
2. CPU ControlLogix 5555 (slot 0, catalog 1756-L55 A)
3. 2-Axis servo controller (slot 1, catalog 1756-M02AE/A)
4. DC Input card (slot 5, catalog 1756-IB32)
5. DC Output card (slot 7, catalog 1756-OB32)
6. EtherNet/IP communication bridge (slot 8, catalog 1756-ENBT A)
7. DeviceNet card (slot 9, catalog 1756-DNB)
Now, from my limited IT knowledge I think the EtherNet/IP bridge should connect the PLC system with some external IP network. But strangely enough, there is absolutely no connection to this module, except the backplane.
There is an HMI connection in the system, but that is on the DeviceNet card, and through a CANbus cable.
Does anyone know why the EtherNet/IP card is there? Can it have any function I'm missing?
Now about the breakdown. The symptoms are . . .
- CPU starts up. "OK" and "RUN" LEDS glow right. "I/O" LED blinks.
- Servo controller - "OK" LED blinks. "FDBK" and "DRIVE" LEDs for both channels remain off.
- DC Input card - "OK" blinks.
- DC Output card - "OK" blinks.
- EtherNet/IP card - "OK" on. "NET" blinks. "Link" off. Scrolling display says "Link Lost".
- DeviceNet card - "OK" blinks, "I/O" blinks, "MOD/NET" on.
- HMI starts up, cannot read any param from the PLC
I need to fix the breakdown and get the production line back immediately. But I cannot find any clue. Is it possible that the EtherNet/IP card is looking for a link and finding none, it is stopping the CPU?
We have two other machines like this, and both have similar Ethernet card with NO external connections. None of them are reporting "Link Lost".
Thanks much for your time. I really need some insight into this mystery. Best regards.





RE: ControlLogix 5000 EtherNet/IP Mystery
I do not think the Ethernet card is faulting the system. You would have a solid red LED on the Processor card. Is the Processor faulting? If so, can you go online and see what fault is being enumerated?
The Processor I/O LED flashes green when the Processor has been configured for a certain I/O layout but it is having problems communicating with one or more I/O modules.
I would guess the Ethernet card is an unused part of the system - installed but unused - maybe for future data collection. Or it could be configured as an adapter for remote I/O. This scenario might explain most or all of the flashing LED's.
Go to these links and download the user manuals for the Processor and Ethernet card:
http:/
http:/
RE: ControlLogix 5000 EtherNet/IP Mystery
However while that process will clear a processor fault, it will not fix the issue that caused that fault. In order to do that, you will need to get a working copy of the RsLogix 5000 programming software. Or call the people that built the machine.
RE: ControlLogix 5000 EtherNet/IP Mystery
Nothing wrong with the PLC system according to your description.
I suggust that: Check the linkage between Servo controller and the stamping machine, and the status of the machine.
RE: ControlLogix 5000 EtherNet/IP Mystery
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: ControlLogix 5000 EtherNet/IP Mystery
As indicated by all contributors here, the EtherNet/IP card was not a problem. The OEM placed it there to download their program into the system (faster than the serial link). It did not do anything useful in my system, and it was NOT the cause of the failure I faced.
I made a gross mistake in evaluating the AB system's health. I thought the CPU still has its program in place. The "OK" LED was green, indeed. And on a couple of occasions, the system came back to life, after the failure. But the revivals did not last long. I was hopeful that the program inside is OK. I was wrong.
ControlLogix CPU will glow the OK led green, even if it doesn't have a program but the CPU hardware is OK. It has a flash backup, and it does try to restore the application from flash, if it detects any corruption in the main copy of the app.
So, I speculate that, somehow my application memory got corrupted, and the system went down. But upon next power up, the CPU tried to copy the app into the main memory, and the system cam back to life. However, the main problem in the CPU memory was not rectified, naturally and the system failed repeatedly.
All these conclusions were reached externally, because we do not have AB software (RSLogix 5000). I did download free copy of RSLinx which showed that the whole system backplane and the DeviceNet network are fine.
The OEM finally sent another CPU with program loaded, and plugging that in solved everything. We lost more than a week of productivity in that line.
RE: ControlLogix 5000 EtherNet/IP Mystery
RajeevCell:
Thanks for the follow-up. The solution to the original problem is always nice to know.
RE: ControlLogix 5000 EtherNet/IP Mystery
Yes thank you for letting us know what the problem was. Your next step is very important also. Most people will mark this off as problem solved and move on. I would suggest that your team get together and evaluate the reaction to this issue and what methods would have brought the line up faster. It is much easier to look back at reactions to an issue and see ways to do it better than it is to evaluate things in the middle of the problem. I suspect when you figure your lost revenue due to downtime, it would have been cost effective to have the OEM tackle the issue. At the bare minimum, the cost of this downtime should justify you having a copy of RSLogix5000 onsite. You may also want to look into giving your OEM remote access if they dont already have it. I am glad you are back up, but dont forget to look back and see what hampered your efforts.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com