AB 842D Series Absolute Encoder

Hello all. Looking for a bit of help concerning the service code necessary to save parameters to an 842D absolute encoder. The user manual is junk. From previous experience, when using RSNetWorx to change the rotation parameter, you need to also save to EEPROM by accessing the class instance editor. I don't have the luxury of the end user having RSNetworx to change this (if necessary - also, I really don't want techs to be able to gain access, for fear of REALLY messing things up). I can sucessfully change the rotation param via messaging, but there seems to be no documentation explaining what the service code is needed to save to EEPROM. Has anyone else ever run into this (and had success)? Any help would be appreciated. I'm slowly going bald over this, from self-punishment.

I read in the Knowledgebase that the User Manual used to have an error, but the copy I downloaded tonight (Jan 2004 revision) appears correct.

On page 4-7, in the section titled "Saving Parameters to EEPROM", it says that you must send the Save service (0x16) to the Encoder Object (Class 0x2F, Instance 0x01). If you are using the RSNetworx SCIA editor, you uncheck the "send attribute" box so that the message contains only the Class and Instance.

I think if you were doing this message with a controller, you would just leave the Attribute value at 0.

Is that section in the copy of the manual you have ?

Are you using a Logix or a SLC/PLC controller ? I presume that you are familiar enough with explicit messaging to give this a try.

(and no, I haven't used that device. I just have nothing to do but laundry tonight.)

Eddie,

Thanks for pointing that out to me. In my haste to get this segment of the project done (3/16/05 deadline), I overlooked it. I've got it going sort of.

Now..........................

I get a connection failure error in my save message. The change rotation message works fine. After doing a search on 'connection failure', I am still stumped. Any insight?

Thanks,

bone

Sorry,

I'm rushing things again. Just need to step back and do a little more reading. I think I found the error. My link address is not available. Will wait longer before I jump the gun and come crying Wolf.

"Connection Failure" and "Link Address Not Available" generally means that you mis-typed the node address for the message instruction. I suspect that the 845D is a "group 2 only slave", so the scanner should easily message to it once it has realized that it won't respond to UCMM messages (that will take 2 seconds the first time you send a message, after which it should remember).