Festo Электромотор MTR-DCI - Manual (Page 268)

B. Supplementary information
B-62
Festo P.BE-MTR-DCI-PB-EN en 1209a
Checksum <PS> The higher-order controller must compare the sent command
with the “echo” from the MTR-DCI and evaluate its checksum.
If checksum checking has been activated for telegrams re-
ceived from the MTR-DCI (see CI object 20F3h), the higher-
order controller must insert a checksum in front of the end
character (CR = Carriage Return).
Checksum (PS)
PS composi-
tion Sum of all sent bytes, abbreviated to 1 byte
(modulo 256).
W: asc(char) “=IIIISS:<value>” modulo 256
R: asc(char) “?IIIISS” modulo 256
PS format 2 hexadecimal digits, UINT8
Syntax W: =IIIISS:<value><PS><CR>
R: ?IIIISS<PS><CR>
Tab. B/13: Checksum
Object 2FF0 Transmission error between host (PC) and destination device,
e.g. due to error in host command:
– Incorrect initial character, separating character or empty
character
– Incorrect hex digit
– Incorrect value type
Name Class IIII SS Type Acc
communication_
error Var 2FF0 00 UINT16 R
Value Comment
0xFF In the case of a transmission error, the value <0xFF>
will be transferred instead of the usual response.
0xFFFF Missing checksum (see CI object 20F3h).