Does anyone have any experience with similiar faults? It seems to happen when two or more online users accept a rung edit at the same time (different rungs, different routines). When it occurs, we loose all communications but the PLC remains in run mode. In order to restore communications we have to cycle power to the processor. In doing this we recieve a major fault that clears all memory within the processor (even with the battery in place), requiring us to download and restart the processor. AB tech support recoqnizes the problem with no real solution other than coordinating our online editing. We are considering upgrading to Ver. 10. Any insight regarding these issues would be much appreciated.

Thank-you,
Jason Hineman

 

The RSLogix5000 version 10 online help also mentions possible faults like yours. I suggest you consult the documentation (online help) that you received with the software.

It describes how RSLogix 5000 allows multiple users to be online on the same controller simultaneously. But there can be problems.

I suggest that you lock the controller to avoid these errors. The “Lock Controller” command is also covered in the online help.

Hope that helps,

- Chip Hinde

 

First, what should happen is that one of the users should be booted offline. This is what happens with the SLC processors. So, as with other things, AB probably didn't properly implement this function in ControlLogix, resulting in your cleared memory.

Second, I'm curious to know under what circumstance two programmers need to edit logic in one processor. Could you imagine the chaos that might ensue if two programmers assembled edits to the same rung at one moment?

Anthony Kerstens P.Eng.

 

Jason,

I recieved a Product Service Advisory Notification recently advising to upgrade firmware to 10.26 and it may be what you are experiencing.

"Ref: ACIG 2002-06-001

"With the 1756-L55M12, -M13, -M14, -M16, -M22, -M23, and -M24 ControlLogix5555 Controllers, Series A, Firmware Revisions 8.x, 9.x, and 10.25, hereafter referred to as the controller, the following functional issue exists:

"Functional Issue - Running Out of Memory Causes Communication Lock-Up or Controller Failure"

Regards,
Trevor Ousey

 

I have seen both of these problems but they were not related specifically to online edits. If a Controllogix Ver. 8 is executing a message and the link is lost the proccessor will stop communicating and will require a reboot to recover. In the case that I saw this, it was a
result of loose wires on the power supply to the processor and ethernet switch. The processor is sensitive to power bumps and can lose it's
memory, even with a good battery. The problem with communications should be solved by upgrading to Ver. 10. There is a tech note on the Rockwell web site regarding this. Check the power supply to the processor and you will probably find the
source of the memory loss problems.

Cheers,
Dave Campain

 

Your ControlLogix is running out of memory whilst editting. Rockwell posted a fix for the L55 processor firmware (v10.25) recently. You can get it from their support download site.

 

Anthony,
Thank-you for your input. I think that you are probably right in saying that AB didn't properly implement a multiple connection reguest handling into Controllogix.

Chip Hindes suggestion of locking the controller before editing does provide a solution, although this is a cumbersome process (I will look into the online help with Ver.10). I have heard that Ver.10 has some substantial improvements in other areas and was wondering if this issue had been resolved.

To answer your second question, I believe that it is fairly common on large projects to have multiple programmers working online on the same processor. I am currently working on developing a large assembly line, we have four programmers working online on the same processor. We break the line up into stations and designate a separate routine to each station. This way no two programmers are working within the same routine.

This works well except for the occasional instance when two programmers accept a rung edit at the exact same time. This causes a connection request conflict that seems to crash our communications, and cause a major fault. Once the development of the project is complete, we will probably never see the problem again due to fact that there only be one person working online. However, during our 3-6 month development stage this issue gives us headaches (this is where all you Siemens fans jump in...I know it's not an issue on with Step7 sofware).
Anyway, if anyone has any insight it would be much appreciated.

Thank-you,
Jason