Honeywell UDC2300 Product Manual page 32

3.4 Request Messages,
Request message
field selections,
continued
22 RS422/485 ASCII Communications Option Product Manual
Continued
Table 3-4 Request Message Fields Definitions, Continued
Selection
Data Type Field A two-digit number that specifies the format, or data type,
of each of the parameters that can be accessed in the
UDC controller.
11 =
18 =
DD = ASCII Text – Used with loopback protocol only.
Data Field The data in this field is determined by the type of request:
• READ – three digit parameter code which identifies a
• WRITE – three digit parameter code, which identifies a
• READY – three zero's (000) – used in conjunction with
• LOOPBACK – ASCII Text
Checksum Field This field is a one byte hexadecimal value (two ASCII
(Optional) characters) representing the binary sum, ignoring carries,
generated by adding the ASCII code for each character
in the message exchange, up to but not including the
checksum and the CR and LF characters.
• No Characters = No Checksum
• HH = two digit hexadecimal number representing the
Carriage Terminates a message. The message will not be
Return/Line Feed exchanged unless used in this order (CR LF).
Definition
Single Byte Decimal (unsigned) – used with
configuration protocol for digital parameter code
numbers 128 through 255.
Floating Point Format – used with configuration
protocol for analog parameters code numbers 001
through 125.
particular parameter for which you want to know the
value or selection.
particular parameter you want to change, a comma (,),
and the value or selection you want to enter.
a write request. Sent after a write request to verify that
the information transmitted was received.
calculated checksum
10/00