5.3 Standard Physical Units
New document uploaded to reflect changes from discussions.
Justification: We want our instance master control device to know whether instances have been set in a device or not (i.e. the device is freshly installed after production). This will increase the speed of instance assignment and reduce unnecessary user input.
Therefore, we want to set an instance value which signifies an unconfigured device.
Instance 0 is a special value according to table 5.3 (means all) and from table 3.2.3b I note the following special cases:
255 – Data not available
254 – Out of range
253 – Reserved
Therefore would like to suggest addition of special case instance 251 = unconfigured device. The idea is that the system can quickly identify devices that have no set zone of operation and allow the user to easily configure the correct device.
Since we are updating the table, I would add the special cases from 3.2.3b to complete the reference table.
| Attachment | Size |
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| 5.3 Standard Physical Units(Revised).docx | 17.08 KB |
If desired, a note stating
If desired, a note stating that for instances, "Out of Range" can mean "Not Configured", could be added to the document.
OK. I think this update is good because we would normally answer out of range with some error message.
There are likely many devices in the field that already use 251
The defention table allows only up to 250 so I am not sure how any currently implemented request for 251 would be answered by any third party device that is implemented purely from the specification. We will implement our solution with 254 as 'not configured'.
OBJECTION There are likely
OBJECTION
There are likely many devices in the field that already use 251. And it seems that the purpose of the submission could be achieved by the submitter using 254 instead. If desired, a note stating that for instances, "Out of Range" can mean "Not Configured", could be added to the document.