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Old December 18th, 2015   #4
ericthegeek
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Join Date: Aug 2008
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Quote:
Originally Posted by dj41354 View Post
from ANSI E1.20-2010 Section 6 Message Structure:
sub-section 6.2.8 Message Count:
...
This paragraph certainly makes it sound like the Message Count field is used by QUEUED_MESSAGE, not STATUS_MESSAGES... so I guess I'm still unclear on this..
It's a good question, and your interpretation is perfectly valid. The ambiguity arises because of Section 10.3.1 paragraph 3:
"A responder with no messages queued shall respond to a QUEUED_MESSAGE message with a STATUS_MESSAGES response."

This means that a status message can also be collected by a GET QUEUED_MESSAGE request, thereby fulfilling the requirements of the paragraph that you quote.

I think your interpretation (that only Queued Messages should be included in the message count) is the better interpretation, but there are others who disagree.

Quote:
Originally Posted by dj41354 View Post
1) Is it ok to implement STATUS_MESSAGES and not implement QUEUED_MESSAGE?
(you said in your 4th response to me above: "You have to include Queued Messages, whether you include status messages in the count is up to you."
I'll re-state it like this: "You have to include any outstanding Queued Messages in the Message Count field. Whether you include status messages in the Message Count is up to you."

By way of example: If you have 2 queued messages and 3 status messages waiting, then the message count could be 2 (queued messages only), or 5 (Queued plus Status messages). It's your choice, just as long as you're consistent.

Support for the STATUS_MESSAGES and QUEUED_MESSAGE PIDs is optional. You can support either one of them individually, both, or neither. It's entirely up to you.

Quote:
Originally Posted by dj41354 View Post
2) If Message Count is not used with my implementation of STATUS_MESSAGES, how does the controller know to ask for device status?.. does the controller just do this occasionally on it's own?
Many controllers will poll for status and/or queued messages on an ongoing basis. Common (but not universal) behavior is to poll each responder every few seconds.

Quote:
Originally Posted by dj41354 View Post
Thanks for you help with this..
Happy to help. That's why these forums exist. Hopefully you'll stick around, and maybe in a year or so you'll be the one answering questions!
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