90-70 Failure

robertm1 · Mar 17, 2009

Hi all, I am a maintenance engineer. I have had three GE 90-70 complete failures in the last two weeks. Has anyone ever had complete communication failure on these processors, only to find after replacing the module that they start communicating again.
Communicating through ethernet card on network. Model number IC697CPX935.

Steve Bailey · Mar 17, 2009

Need more information. Which CPU model? Serial communications or ethernet? Communicating through a port on the CPU or through a communications module?

robertm1 · Mar 17, 2009

Communicating through ethernet card on network. Model number IC697CPX935.

Money4Nothing · Mar 17, 2009

It's hard to believe that 3 consecutive processors would fail in the same way like that. Its sounds very much to me like you have a problem with your communication wiring. Eliminate that as a potential source of problem before looking at the processor. Check for broken wires, incorrect terminations, crossed conductors, improper shielding.

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robertm1 · Mar 17, 2009

Hi all, I am a maintenance engineer. I have had three GE 90-70 complete failures in the last two weeks. Has anyone ever had complete communication failure on these processors, only to find after replacing the module that they start communicating again. These are on three different applications but all on the same network. When they quit they dump the memory with no faults in the table. I can replace the module and then place the bad one a test stand the next day and it has no issuses. I have sent one off to GE for failure analysis. I still have the other two in shop.
Communicating through ethernet card on network. Model number IC697CPX935.

Steve Bailey · Mar 17, 2009

Now I'm more confused than I was earlier. When you say "dump the memory", do you mean there is no longer a program or configuration or data in the PLC? That would mean the entire process controlled by the PLC shuts down as well. Is that what is happening? Or is the problem in the ethernet communications module?

rkicklighter · Mar 18, 2009

IC697CPX935 is a 90-70 CPU, it's only onboard communications is serial. Are you using a 90-70 Ethernet card? Which one? What else is in the racks? When the system "goes down", is the processor still in run mode? What is the LED status on both the processor and Ethernet card?

Have you tried connecting the the processor via serial port during an episode and view the fault tables? We need much more information to assist.

robertm1 · Mar 18, 2009

I am using Ethernet communication card IC697CMM742HJ. I have not had time during the breakdown to hook up to the CPU via serial due to line downtime. I first tried changing out the Ethernet card. All CPU and Ethernet card indicator lights will show normal. I did hook up to one via serial and it would not communicate. When I say the memory dumps, I mean that when I hook the CPU up on the test stand all registers have been written to zero and all RM are reset. This is even when there is still battery power. Also I did after several power ups and down get one CPU to come back to life on the line and all memory was dumped. What is getting me is I still have both hooked up right now on test benches and on the network and neither has faulted out.

rkicklighter · Mar 18, 2009

It would be nice to see what's in the Fault Tables if possible. If the CPU is still in run mode, communications should be possible. The fault table will narrow down the problematic area.

Did this start all of a sudden on all 3 or has it been happening for sometime. It's really a weird problem I have never seen on a 70 series. 30 series, early 374 CPU, yes. But never on a 70.

Just going from what is posted here, sounds like something is generating a massive flood of faults to the point where the CPU can't handle them anymore and goes down.

Is there anyway to run the line without Ethernet connected?

robertm1 · Mar 18, 2009

Can not run the line without ethernet communications. This had happened all of a sudden with no prior history. All three CPU systems were in different areas of the plant. That is why I'm so concerned. We have about 41 90-70 series plcs running in the plant.

robertm1 · Mar 19, 2009

Update on these post: When I say dumped the memory I also meant to say that the CPU dumps all programs. It is like you removed power with no battery back up. It is dump just like a new CPU. We have GE reps coming in today to analyze the back plane and the CPUS. I was successful in pulling up one string of fault history so maybe this will help. Also, most of these failuers have had a checksum fault. Thanks guys for all your help and please offer anymore information that you might have.

90-70 Failure

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