CONTREX CX-1200 - Manual (Page 243)

7 - 4
CX-1200 Serial Communications ASCII Data-Link Protocol
(Message Transmission / Response Structures)
STX 1 Byte ^B Char(2)
Address 2 ASCII Chars
Function 2 ASCII Chars
Message Error 2 ASCII Chars
Data Field Number of characters defined by Function
ETX 1 Byte ^C Char(3)
CRC 4 ASCII HEX Chars (0000 - FFFF)
Number of constant characters per Transmission = 10 characters (Minimum # of characters)
CX-1200 Serial Communications Buffer Size = 255 characters (Maximum # of characters)
(leaves a maximum of 245 characters for the data field)
Note: In this document pertaining to ASCII protocols, any reference to ASCII HEX or “0-F” refers to ASCII
representation of a HEX number using ASCII characters “0-9” & “A-F”.
Functions that are included in the ASCII Protocol:
01) Data Read Single Parameter
02) Data Write Single Parameter
03) Data Read Parm Block (14 parameter limit)
04) Data Write Parm Block (14 parameter limit)
05) Control Command Send
08) Data Read Custom Engineering Units
09) Data Write Custom Engineering Units
10) Data Read Constant Table (4 parameter limit)
Example:
Request Value for CP-210
Table 7-1 Data Read Single Parameter, Host Transmission
STX ADDR FUNC DATA EXT CRC
^B 0 1 0 1 2 1 0 ^C F 4 4 6