COmpactLogix - read/interpret diagnostic information after major fault

Hi all,

Trying to remotely diagnose a machine with a 1769-L16ER-BB1B Compact Logix. When I connected I found it had a major fault, power up fault, type 1, code 61. According to the message (and the manual), this means that the controller wrote diagnostic information to the memory card, then cleared the PLC's memory.

As I'm not onsite, I don't have access to the SD card, and in order to get the running again, I have re-downloaded the program. A few questions to help with my post mortem:

1. Now that I have downloaded the program, is the diagnostic information still saved to the SD card?

2. If the answer to #1 is "yes", are these diagnostic files of any use to me, or are they only useful for sending to Rockwell technicians who can interpret further?

3. If they are of any use to me, could I have a local tech remove the SD card, put it into their laptop, and email me whatever files are on it? Or do the diagnostics have to be reviewed via the Logix software while online with the PLC?

ASF said:

Hi all,

Trying to remotely diagnose a machine with a 1769-L16ER-BB1B Compact Logix. When I connected I found it had a major fault, power up fault, type 1, code 61. According to the message (and the manual), this means that the controller wrote diagnostic information to the memory card, then cleared the PLC's memory.

As I'm not onsite, I don't have access to the SD card, and in order to get the running again, I have re-downloaded the program. A few questions to help with my post mortem:

1. Now that I have downloaded the program, is the diagnostic information still saved to the SD card?

2. If the answer to #1 is "yes", are these diagnostic files of any use to me, or are they only useful for sending to Rockwell technicians who can interpret further?

3. If they are of any use to me, could I have a local tech remove the SD card, put it into their laptop, and email me whatever files are on it? Or do the diagnostics have to be reviewed via the Logix software while online with the PLC?

Click to expand...

I have no experience with this specific PLC.



In my experience with many other systems, log files/disgnostics files written to external storage are not generally cleared. If it was important enough to log the exception, it's important enough not to clear the file.


So for question 1 I would guess Yes, Question 2 I would guess Rockwell only, Question 3 depends on if you want to see it anyway before sending on to Rockwell.


It is possible that the files will be over-written on the next fault, if there is one.


The file dumps that I have personally seen have required specific software from the vendor to interpret. Sometimes there is one log file that is plain text and will give you a bit of an overview of what happened.



Modern equipment that is written in C++ or C# has many structures, and the log files are simply dumps of one or more of these structures.


I have never had a diagnostic file where I had to be online with the PLC. In their most explicit case, the diagnostics will refer to a rung number within the program and perhaps a data structure that was found to be corrupt, a pointer invalid, etc.


Personally, I would ask the client to change out the PLC, load the program into it, then send the crashed PLC to Rockwell for investigation (if it is a critical process) or keep it for a 'lab' offline test machine. It depends on how badly you want to find out what went wrong, and what that will cost.


If the machine can be taken offline with no 'downtime' costs, what you have done may be good enough

Thanks. It's certainly not a critical system, and the customer is happy enough to write it off as a freak one-off. These machines are mobile machines, and are frequently unplugged, relocated, and re-powered up. So the chances of a power up MNRF like the one just seen is higher than usual, since most PLC's rarely if ever get powered down. Even this one has been living its itinerant lifestyle for over 5 years now, without any such faults until now.

I just hate not knowing, and if there's information anywhere that can help me not-not-know a little less, well, I always like to not know as little as possible!

Hi ASF,


I recently had an experience with a 5069-L306ERS2 (I know different PLC) with a similar fault code.

When jumping through the hoops with technical support, they asked for the contents of the SD card to be sent to them.
Apparently, these files were not even to be examined in OZ, they had to be sent to the states for someone else to look at.
So, the tech support guys in OZ had no ideas on what they contained (that was what I was told).

My fault was traced back to me doing online editing of the (unlocked) safety program - I don't know if they knew already that they had a bug with this - I was lucky that this was found before the panel went into production.

For more info..
https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/1131169


Also, this one if you have TechConnect
https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/278692/loc/en_US

Thanks Ian, good info. I don't think anyone on that site cares enough to send their data to the US for analysis, they're just happy it's working again. And if that's what RA were going to do with it, I suppose that answers my question as to whether or not I would be able to do anything with the diagnostic info!