PLC-5/40L Ethernet connection problems

We have had an issue on a machine which needed us to go online to the PLC to check certain operations. We have never had any issues doing this in the past but today we are getting a fault where rslogix 5 pops up the windows fault screen asking if we want to send an error report, when clicking either send or don't send rslogix then shuts down. To go online I normally open rslogix then use the "who active go online" option, this is when we get the error message. If I open the rslogix file and then use the online button I get "unable to connect application layer time out" message but rslogix doesn't shut down. If I open rslogix 5, but don't open the project file and then click the go online option and create a new file, then I can go online OK. When comparing this new file to the original I find the differences between the two files is in the I/O configuration, images attached to show the differences ( "Original file not working.jpg" is the correct I/O). I have tried a different PC and get the same results, also tried deleting the harmony files. Never had an issue like this so no idea how to resolve the problem.

The PLC is a PLC-5/40L with a1785-ENET card. I should say that the machine is working and connected to remote racks and also use DH+ all this functions correctly, we needed to go online to find some conditions that disable certain functions, there was no actual fault.

If windows message error, I believe it is a software problem. Have you changed any of the environment (OS,software updates) since you have last been online with PLC?

"fault"? are you sure you are getting fault or just windows error? Been awhile since I have used rslogix5 but from what I remember you must have the current program to go online.

robo77, as I have shown in the attached images, the file that allows us to go online does not reflect the actual configuration. No changes have been made to the PC and we have tried a different PC with the same results.

Not sure what the issue is, but a suggestion to get around it....

Go online as you have. Save the PLC to the new file.

Open your original file and export the comments etc, then go to the new PLC file and import the comments. Save as a new file, then try and go online again.
Do you get the same fault?

The online configuration does not contain the chassis information of the offline project. That is normal.

RSLogix saves the online connection method of the last time you were online and saved the project. For some reason this online connection method is not possible any more. That is why you get errors when you try to use the "who active go online" or the "online" button to go online.
You may have to configure your online connection from new again. Select "Communication" from the main menu.

Apart from that, JohnCalderwood is correct in that you should be able to merge the old offline program and the new uploaded program.

N.B. all of the above is from memory since I havent worked with RSLogix5 for more than 10 years. Maybe the details are a bit off.

If it is an "online" setup issue then that will be what is saved in the project as the "project path".

If the PC you are using to access the PLC does not have RSlinx setup with the exact config as saved in the PLC Project Path, then it will not find the PLC. It will prompt you to find the PLC in your RSLinx configuration, where you can see it online, then you would "save Project Path" with the project.

Tools, Options, System Communications will show you the project path as "Comms Path"

I haven’t seen any mention of RSLinx. I’m wondering if it was running in the background in the past and now isn’t running. I’d check to see if RSLinx is running and can see the PLC.

Thanks all,
John - I had already exported and imported before you suggested it, this does work and I can go online again with this file, however one of the first commands is a MSG instruction, If I try to view this instruction I get a message that the instruction is not possible as there is no module configured in the I/O configuration.I have copied the I/O Configuration from the old file but still get this message. The MSG instruction is BTR and BTW for analogue cards.

I had tried editing the project path but still the old file shuts down rslogix with the error message. Even though the connection is via ethernet and is connected to a switch the original file had a long CIP path as the project path, don't know why as the physical setup is:
PC---->switch---->PLC.

I suspect one of the techs is doing something wrong when trying to go online as I imported all the comments yesterday and could reconnect to the PLC, but when I have come to work tonight the tech said he had the same problem as yesterday and had lost all the comments again, and the PLC was in test when he did get online. I left the machine running before he came on shift. Comments are a pain as many get truncated during import.I found my file from yesterday in the recycle bin and it crashes rslogix again. One thing I did notice is the original file is 2680kb but the new file with imported comments is only 1400kb

Thanks again chaps, will continue to investigate.

Food for thought. I’ve had problems going on line with a PAC (a CompactLogix in my case) if it was busy executing a message instruction that was not responding. It’s not until the message instruction finishes can I then go online. When I see this I put the processor in program mode so that when it finally errors it won’t re-enable keeping me locked out. I don’t know if this is what you are/were seeing but just a thought.

The I/O configuration on a PLC-5 is purely for your convenience, it only matches your configuration if you type in the information correctly. It is not built by exploring the chassis like a SLC.

That being said, the one thing that uses the I/O configuration data is the wizard for the MSG instruction.

Thanks mellis that is good to know.

CRMCC,

get the techs to leave it alone!

Make sure you take your own backups on a USB stick or rename them with your initials and/or date and file them away safely....