Festo Электромотор MTR-DCI - Manual (Page 284)

C. The Command Interpreter (CI)
C-10
Festo P.BE-MTR-DCI-DN-EN en 1209a
If the MTR-DCI detects a checksum error then, instead of the
normal response, the value <0xFFFF> is transmitted (see
object 2FF0h).
The checksum is calculated according to the capitalisation
(uppercase/lowercase) of the
command; the response
checksum is always calculated based on uppercase letters.
Checksum <PS> W/R Command Response
Default
(CI object 20F300:00) W =IIIISS:<value><CR> =IIIISS:<value>< PS><CR>
R ?IIIISS<CR> =IIIISS:<value>< PS><CR>
Optionally
(CI object 20F300:01) W =IIIISS:<value>< PS><CR> =IIIISS:<value>< PS><CR>
R ?IIIISS>< PS><CR> =IIIISS:<value>< PS><CR>
W = write, R = read
Tab. C/5: Syntax of a command/response (optionally with checksum comparison by the
MTR-DCI)
Checksum <PS>
Calculation Sum of all transmitted ASCII characters, reduced to
one byte.
W:
<PS> = “=IIIISS:<value>” modulo 256
R: <PS> = “?IIIISS” modulo 256
Example:
Command =IIIISS:<value><CR>
=20F300:00
ASCII > = 2 0 F 3 0 0 : 0 0
HEX 3D+32+30+46+33+30+30+3A+30+30
Sum 212h
Mod 256 212h mod 100h = 12h
Response =20F300:00
12
Format 2 hexadecimal digits, UINT8
Tab. C/6: Checksum