GV3000 ControlNet/ControLogix write error

Hi all,

Been in the industry for many years and this is the 1st time I've encountered this error message. I'm using a 1756-L51 v20 PLC with a Reliance GV3000 on ControlNet. A couple of months ago thr writes stopped working. (Just got the call last week.) The message reads work fine as do scheduled communications. The error code I get back is 16#f00b - "Privilege error - access denied."

I'm trying to write 5 words to the drive but have tried reducing this to word. Even so ALL of thr other communications work. Finally, when we cycle power to the drive the data DOES get written over, evidently just once.

Any ideas?

Thanks!

Yosi

So the Read instructions from the drive work, but Write instructions don't? This might be a dumb suggestion, but is there any security/login settings on the drive, that prevent unauthorized users from changing drive parameters?

Thanks for your reply.

Not only do the reads work but the scheduled reads AND writes work! It's just this unscheduled write. What's really strange is:
* It used to work and for some reason stopped
* If we cycle power to the drive it will get the data we're writing over. I don't know if write works just once or for a short period of time.

This drive is very old and according to the drive guy there is no security/login. I started thinking along the lines of PLC-2 protected write but, again, why would it stop working? Why would the scheduled writes work? Why would writes work after PTO? Very strange...