Mute Response Question - E1.20 RDM (Remote Device Management) Protocol Forums

sondericker · July 24th, 2006

Hi Scott,

Yes, I believe I have seen this occur. It stumped us for a few days in fact. It happens if you have just the right 3 UID's that are numerically close to one another. The "wire-or" that makes A&B look like C changes the checksum perfectly, as it is only one bit that changes in the message and one bit that changes in the checksum. A's UID is one bit off of that of C and B's UID is also one bit off of C. We're using a very high speed processor with interrupt driven serial algorithms so the response synchronization across multiple responders is very tight.

We'll deal with it by having the controller notice when its happening and continue to branch. I hope -- unless I'm totally mistaken somehow -- that this thread will some day save someone some frustration.

-John Sondericker
Wybron, inc.

dfleenor · July 28th, 2006

The only controller I've written is the RAD which always goes to the bottom of the tree. If this problem occurs on fast-discovery we should probably write up a description and add it to our knowledge base along with the solution (if a device appears to respond to a discovery message after being muted, branch further down the tree). Do we have a knowledge base as part of this forum?

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July 24th, 2006	#1
sondericker Banned Join Date: Jun 2006 Posts: 11	Hi Scott, Yes, I believe I have seen this occur. It stumped us for a few days in fact. It happens if you have just the right 3 UID's that are numerically close to one another. The "wire-or" that makes A&B look like C changes the checksum perfectly, as it is only one bit that changes in the message and one bit that changes in the checksum. A's UID is one bit off of that of C and B's UID is also one bit off of C. We're using a very high speed processor with interrupt driven serial algorithms so the response synchronization across multiple responders is very tight. We'll deal with it by having the controller notice when its happening and continue to branch. I hope -- unless I'm totally mistaken somehow -- that this thread will some day save someone some frustration. -John Sondericker Wybron, inc.

July 28th, 2006	#2
dfleenor Task Group Member Join Date: Jun 2006 Posts: 8	The only controller I've written is the RAD which always goes to the bottom of the tree. If this problem occurs on fast-discovery we should probably write up a description and add it to our knowledge base along with the solution (if a device appears to respond to a discovery message after being muted, branch further down the tree). Do we have a knowledge base as part of this forum?