Allen Bradley PLC Error

fredjohns

Member
Join Date
Dec 2008
Location
Pennsylvania
Posts
119
We have a machine that has been in storage for a while and just came back to the plant to get it ready to send off to one of our other plants. The machine has an Allen Bradley 1747-L40C PLC in it. It shows the following error on the machine display:
CORRUPT NRAM ERROR

What is a possible cause for this error and what is the correct way to get rid of it.


Thanks
 
Is it possible that the error is in the display and not the controller? On that note what display is being used?
 
If you have the original program saved somewhere I would try reloading it to the PLC and display to see if either will accept a new download. If you don't have a the program I would still attempt to go online with devices to see if any more information or faults can be found, I have seen where there are more than one but only certain faults get displayed.

Is the status lights normal on the front of the PLC?

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um009_-en-p.pdf

page 92 that section will walk you through diagnosing the status lights on the PLC
 
The 1757-L40C is a *very* old shoebox style SLC.
Sounds like the battery is dead and you have lost the program.
I hope you have a back up!
How long was the machine in storage?
 
I don't really know how long it was in storage. The machine does have a eprom in it but when I try to get the program out of the eprom, it comes up with a compile error or something like that. I am assuming there is something wrong with the eprom. The company purchased this machine used at a very low price but never saw it run. They are contacting Shanklin, the manufacture of the machine to request a new eprom. The machine acts like there is no program installed in it.
 
The "compile error" might just be a software glitch between the very-very-old SLC-500 Fixed IO controller and modern RSLogix 500 software. I remember that if the "Enable Single Step" bit was set by AI-500, then RSLogix 500 couldn't upload the file.

RA offers a DOS-based upload-only utility based on AI-500 for exactly this circumstance. It's in RA Knowledgebase Article 43708 (TechConnect Required).

Start with the basics; what do the indicators on the 1747-L40 tell you ? There are five:

POWER
PC RUN
CPU FAULT
FORCED IO
BATTERY LOW


What model of HMI device is it ? Does the error change if you disconnect the HMI from the SLC-500 ?
 
The error stays the same wether the HMI is plugged in or not. The HMI is an allen Bradley DATM. When I originally tried to connect to the PLC, I got an error that there was no program installed even though there was an eeprom installed. The power light was on, the PC RUN light was off, the CPU Fault was on and the last two lights were off. I was not able to go online with the PLC so I could see what the fault was or to try and reset it. What I tried was to download a similar program from another machine into the PLC, the program downloaded fine and I was able to go online with the PLC, I did get a fault if I tried to put it online since the configuration of the program I downloaded didn't match the current configuration. Now that I was able to go online, I was also able to go to the UPLOAD EEPROM setting and the program started to upload from the eeprom into my PC but when it was almost complete, that is when I got the compile error.
 
That's great information. I suspected that it was a DTAM, since a vendor-specific HMI is one of the few devices that might have a specific display code that can detect a PLC fault or NRAM fault in the PLC.

If I were in your shoes, I would try to use the AI-500 based upload utility to take another shot at uploading from the EEPROM.

If the EEPROM is really damaged, you need to get a program from the OEM or start a new recontrol effort.
 
I have a program saved from an old Shanklin machine. It to is from an L40C processor. The machine I worked on was a stretch wrap machine with hot wire cutters to cut and seal the wrap. It also has a bunch of old Minarik DC cards to run some of the motors. If it is any use to you I can zip and post it here for you or email it. There may be some slight changes from OEM state but it might be enough to get you started.

Let me know.
 
...or start a new recontrol effort.


Opportunity knocks. Unless there is an expansion rack attached to the L40 then the IO count here is small. If you can extract the program or get it from the vendor then switching to a MicroLogix will be easy at this point. If you do have to create one from scratch then seriously contemplate changing to a Micrologix or if you already have RSLogix 5000 then a CompactLogix.
 
I have some other shanklin programs saved but right now I am trying to get a copy of the original program from Shanklin but I definitely appreciate your offer to send me a program.
Thanks
Fred
 
Where can I get the AI-500 based upload utility that you talked about. All I have right now is the Allen Bradley RSLogix500 software. It would be worth a try to use the AI-500 upload utility. Does that program run on its own or in conjuction with the RSLogix
 
It's in RA Knowledgebase Article 43708 (TechConnect Required).

The AI-500 based upload utility is a standalone software utility; it does not integrate with RSLogix 500.

If you don't have a TechConnect contract, ask nicely with your local RA distributor.
 
What exactly does the RA stand for, I am unfamiliar with that. If I need to purchase the upload utility, do you have an idea what it costs.
Thanks
 

Similar Topics

Hi good day Everyone, I have a cimplicity v10 project with 7 to 8k tags communicating with AB PLC through OPC and Rslinx classic. I have this...
Replies
1
Views
82
I am using Allen Bradley PLC 1756-L81E and EIP module 1756-EN2TR for Ethernet/IP communication. My communication works fine but in Get-Attribute...
Replies
2
Views
165
I have a network with 4 PLCs PLC1 is controllogix and PLCs 2-4 are compactlogix and they all need to communicate. The current way I have this...
Replies
8
Views
224
Hi Everyone, I am currently trying to communicate ControlLogix PLCs via EtherNet/IP with Delta V DCS. There is a VIM2 card configured for...
Replies
1
Views
182
Hi everyone. I have an issue with an Allen Bradley PLC model 1769-L30ER. This PLC had a previous program with a different IP address but when I...
Replies
4
Views
492
Back
Top Bottom