Figure 3-8 Failure Response Message Fields - Honeywell UDC2300 Product Manual

3.7 Checksum Protocol (for Data Security),
Failure response
Figure 3-8 "Failure Response" Message Fields
"failure" response
Request Message Status Code
(checksum protocol indicates a problem or parity error)
The failure response may also show that there is a problem with the UDC.
In this case, the response would be:
Request message status code (CHECKSUM O.K.)
UDC Status Code (01 through 07 indicating an error)
UDC State and Mode
Alarm Status
Checksum (for the 4 previous characters)
Checksum Calculation
If there is a problem with the UDC itself, a UDC Status Code indicating an error will be returned.
32 RS422/485 ASCII Communications Option Product Manual
If the checksums disagree, UDC ignores the request and returns the failure
response Request Message Status Code 04. To recover, your computer
repeats the operation. Figure 3-8 indicates this response.
After receiving a response that has checksum protocol, your computer
should perform the checksum calculations on the characters received, and
compare the results to the checksum in the response message. If the
checksums disagree, your computer should repeat the operation.
Continued
0 4
0 0
CR LF
CR LF
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