plc5 question

Hello group
I had a PLC5/80 with eprom go south. I could not connect through the ethernet and the proc led was solid red. All outputs had been turned off but the plc was in REM mode. I connected through DH+ and I was promted to upload and merge existing project. When I did this, it was some old stuff that I did not recognize. The switches on the plc are not set to burn to eprom. I guess the question is do you think the plc dumped it's memory and I uploaded an original generic project burned into the eprom? My apoligizes if I'm not being very specific, I'm still trying to understand what I'm trying to understand!!
Thanks,
Jeff

The switches you mentioned are used to determine when the PLC READS from the EEPROM. Not write.

The PLC-5 never burns to the EEPROM on it's own. You use the RSLogix5 software to burn the contents of the PLC-5 RAM to the EEPROM.

Sounds like an old program has loaded from the EEPROM to the controller.

OG

Oh no! It sounds like you have caused an old obsolete program to load. I really hope that you have a backup of the actual running program somewhere.....Your tail could really be in a crack now!

I actually changed the processor and downloaded the correct program so I could try and figure out what happened. When I got the plc on the bench I found the odd-ball project. Now I am trying to understand why it dumped it's memory and how the eprom works. It seems that we don't even use the eprom, should I remove it or does that even matter?

I think you have answered your own question. If you don't use it then remove it. Or write the current program to it. ( simple) See PDF below.

The EEPROM IMHO is more of a PITA than anything else when you maintain your batteries and have people on staff who are capable of using RSLogix in case of emergencies.

The advatage to the EEPROM is when you need to be able to restore a processor without goning online, for instance when there are no qualified personnel on hand.

The biggest problem I have had with eeproms is that you must shut down the process in order to save the latest edits to them. If you can do that everytime you make edits to the software and stand to gain from the advantage stated above then keep it.

Also, when the PLC reads from EEPROM, it will overwrite the data tables so you may lose all the settings that have been changed from an HMI/SCADA system.

Look at the status file bits to see how the EEPROM is configured. I can't access RSLogix5, but there should be several choices for how/when to load from eeprom, and also a bit that will tell you when a load from eeprom has occurred.

I would ditch EEPROMS here if given a choice, because keeping up with batteries is pretty foolproof, and reloading a PLC from RSlogix is no problem for me. Our boss likes EEPROMS though and wants us to have one in every machine. I always set them up to only load on memory error, so the only nuiscance for me now is making sure I keep them updated with the latest program edits.

Paul

Thank you for the input and clarification. Mickey I'll hold on to that PDF just in case and thank you. I'm still confused on why we lost the program from that processor. As you can tell I'm just an electromech that has been thrown into the PLC fire, stuff like this is way over my head. (1st time replacing and downloading to controller) I was a bit nervous.
Anyways, thanks again for all the advice that this group gives.
Jeff

DIP Switches:
6 7

ON ON EEPROM memory transfer to PLC-5, if RAM is invalid.​

Click to expand...

Also check PLC5 Status bits S:2/13, -14, and -15 in your program.

EEPROM S:2/13 - S:2/14
This single field indicates that the EEPROM transfer is either disabled or enabled. It is based on the settings for mutually exclusive bits S:2/13 and S:2/14. Bit 13=1 indicates load from EEPROM enabled. Bit 14=1 indicates RAM backup not configured.

Memory Protection Disabled S:2/15
This indicates Yes or No. Yes means that the EEPROM memory does not transfer to processor memory.
Rockwell Software Inc., 1997, 1998, 1999, 2000

Click to expand...

Hi Lancie,Yep, switches 6-7 are open and transfer disabled. I guess I can rule out any eeprom issues. Where did you get that "quote" I've been downloading some very good material from the RA site but have not found anything with that kind of detail.
Thanks again for all the help.
Jeff

It is a copy of part of the RSLogix5 software program Help file on EEPROM.