Loopback; Table 3-9 Example Of Loopback Request Message - Honeywell UDC2300 Product Manual

3.9

Loopback

Making sure all the
UDC2300 controllers
are on-line
Loopback message
exchange
Request message
34 RS422/485 ASCII Communications Option Product Manual
Once you have established communications between the UDC2300
controller and your computer and understand the message exchange, it is a
good idea to test communications to all the controllers on the RS422/485
link. The LOOPBACK operation is an easy way to do this. By including
the appropriate address in the loopback operation, you can send a series of
characters from your computer to any device on the link.
After receiving these characters, the device addressed "echoes" back the
same characters. By comparing the characters sent to those returned, you
can tell whether communications are working correctly.
With this message exchange, you can test the communication link
between your computer and any controller.
• In the request message, your computer sends a series of characters to
the desired device.
• In the response message, the device returns the characters it received to
your computer.
Table 3-9 is an example of the Loopback Request Message with or
without the checksum.
Table 3-9 Example of Loopback Request Message
Protocol
With Checksum AA,4204,E8,DD,123456789ABC,CS CR LF
(12 characters max.)
Without Checksum AA,0204,E8,DD,123456789ABCDE, CR LF
(14 characters max.)
Where:
Message Format
AA = Status Address
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