6.1
Data format
For transmission of block length and checksum, the hexadecimal format is used,
whilst set-points and process values are transmitted in BCD format. For
transmission, hexadecimal values are converted into ASCII. For simplification,
values above 9 (A-F) are coded as 3Ah - 3Fh instead of 41h-46h (ASCII A-F).
6.2
Protocol structure
1
2
3
4
5
6
...
n n+1
n+2
Address
Length
Identificaton
Message
Checksum
Byte 1:
Device address of instruments 1 – 32, default 1
•
Master
→
slave (range: B1h...D1h, B0h: reserved)
•
Slave
→
master (range: 31h...51h, 30h: reserved)
Byte 2-4:
Block length; each message contains 3 bytes, which include
(ASCII-coded) the binary number of bytes of the overall message
(including checksum bytes). When receiving, the correct number of
bytes is checked
(range: 30h,30h,37h ... 3Fh,3Fh,3Fh)
Byte 5:
Identification marks the message type,(range: 41h, 7Fh), see below
Byte 6-n:
Information bytes, see below
Byte n+1,n+2:
Checksum; every message is completed by 2 checksum bytes, which
are also counted in the block length bytes. The checksum bytes are the
(ASCII-coded) 8 bit wide sum of all bytes of the message including
block length bytes, checksum bytes not included.
(range: 30h,30h...3Fh,3Fh)
g
Hexadecimal numbers are coded in form xxh, e.g. 41h means decimal 65 or ‘A’
in ASCII.
Communication protocol
Operating note KS 50-1
TCont
15
Data format
