Sign in to follow this  
Followers 0
Datman

Help! SLC 505 NVRAM error!

10 posts in this topic

Hi guys i desperately need your urgent help!! I have searched a bit on the net but dont have any definitive answers... Basically we have an AB SLC 505 which is running a bit of devicenet remote I/O. I'm unsure on the exact hardware configuration as i'm new to this project. Anyway, yesterday we had to make some remote changes. There is a modem on site allowing us to dial into the network and we can then reprogram the PLC's on site. Its a slow dialup connection in to the site but it works. Until yesterday that is... I was performing a code download to the SLC, where is suddenly popped up with "communication error" and dropped out. I can still see the processor online with RSLinx but it is now named "DEFAULT". I cannot seem to download a program to it, sometimes i get the error "The selected processor is not a Micrologix or SLC PLC" or it will start to program, get through "Writing IO tables" etc but the drop out with same "communications error" as above. I have tried doing a who active go online, and i get the following dialogue: Default program loaded due to NVRAM error. A corrupt CRC was detedted (loss of battery power may cause this), or a power cycle in the middle of a user program download, initialize memory or memory module load. I hit OK. Says can not go online from default processor (no Program)You must perform a down load. But then when tryign to download it does all the stuff above and i cant download... I have seen articles on the net about having to do a complete processor reset, pulling processor out removing battery and shorting VCC and GND..???? Basically i want to know if its possible to recover this dang thing without having to drive 5 hours to site... It is a bit of a major... Its weird that it is sayign default but it has retained its comms settings and i can still see the processor with RSLinx. There were no errors within my program and i even tried using the old backup program with no success. any advice hugely appreciated! Rockwell have been absolutely no use whatsoever....

Share this post


Link to post
Share on other sites
I just tried again and the comms error message i get when trying to download the program is simply "Download Failed - Communication Errors". Every time, even with a blank program. Is going to site and programming with a serial lead going to fix this??

Share this post


Link to post
Share on other sites
If it doesn't you might try clearing the processor by removing the battery and shorting VBB to ground method. See PDF below. I would make sure the program is gone first by trying to go online locally to see whats in the controller. ClearMemSLC.pdf

Share this post


Link to post
Share on other sites
ah excellent good to have some concrete advice on how to do this thanks very much!! ok so basically there seems to be no way in hell i can recover this thing remotely. Man the missus will be happy, its the weekend here and a 5 hour drive to the customers plant so that means an overnight stop. ruined my weekend!! Dont even get overtime pay :(

Share this post


Link to post
Share on other sites
bummer. Looks like you may have a 5 hour drive ahead of you. I have had a problem in the office where I downloaded a program and had the same error. My program validated with no errors, same processor, etc. but crapped out the processor. I was able to download an older program to the processor successfully. You might want to try downloading a single rung program to the processor just to see if you can install a program remotely. If that works then the drive isnt going to do you any good - you must have some sort of weird error in the program. I never have figured out what the problem was with my program that did that. The fact that you can see the processor is some indication that there is hope to solve this remotely. Beware of those bad phone connections. One of our engineers wiped a remote program because of a bad connection once in the past. Try establishing that you can load a token program first and then work your way up from there. If not then looks like a nice drive in the country.

Share this post


Link to post
Share on other sites
yea i tried the single rung thing, no joy. It came up with the same communication error once. then the next time i got a different error something about a corrupt processor. yay... and the phone connection is definitely crap.. Unfortunately here in New Zealand some places cannot get broadband, this site being one of them. So the process for dialing in to this particular customer is to connect to their modem using a laptop and bluetooth connection through our 3G cellphones, which connects to their modem, which lets us talk to their main network. ie many pieces in the connection puzzle for cock ups to occur. The silly thing is they have a ML1400 on site which i have programmed many times without issue. The first time i try to program the SLC, this happens.

Share this post


Link to post
Share on other sites
ah dang... looking at the instructions above, we have a modular SLC not a fixed IO SLC. Does anyone have any instructions/diagrams on how to reset this memory in a modular SLC?? picture of said culript processor is here:

Share this post


Link to post
Share on other sites
The PDF posted did cover the fixed and modular SLC500s - read through the whole thing. Unfortunately someone still has to be there.

Share this post


Link to post
Share on other sites
One often overlooked "trick" when accessing PLCs via modem is the modem configuration. Now I can hear you saying but I bought the RA recommended unit it's a blah de blah blah top o'line unit with all duh latest bells and whistles. Well that's great if you're in a major american city where the phone system goes almost straight to fiber optic, but in rural america or the rest of the world they still use analog switches, multiplers and such and the audio quality and hence the modem performance is carp. For these reasons I recommend you configure your modems to force themselves to either 9,600 ; 14,400 or possibly 19,200 both at the PLC and the PC. Also set the PLC to match this baud. For a questionable quality phone connection I've had good success with 9,600 where 19,200 would drop out. Forcing the modem to operate at your pre-chosen speed eliminates auto-negotiate waits and losses of comm when it trys to adjust to a faster speed cause it thinks it can when phone line quality says it can't. Just MHO

Share this post


Link to post
Share on other sites
Having the processor name show up as "default" means the controller has erased the application program, though not the IP address configuration. This is actually a good sign; the controller *should* be loadable. If it is not, then you either have a genuine hardware failure, or the network connection is so poor that a program cannot be loaded without data errors. I realize you're probably driving right now, but I'm curious about the long string of devices in the connection. Laptop -> bluetooth -> 3G phone -> cell tower -> [national cellular packet network] -> cell tower -> 3G Modem -> Ethernet LAN -> SLC-5/05 In theory all the error checking and packetization should allow this to work. In practice, not so much. Are you using a serial DF1 drive in RSLinx, or an Ethernet driver ?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0