KROHNE CORIMASS MFC 85 Interface EN - Manual (Page 17)

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5. Converter Configuration
Setting up the RS 485 System:
Use the 3.11.0 Serial I/O menu to set up the RS 485 communications:
Fct. 3.11.0 Serial I/O
Fct. 3.11.1 Protocol
Select OFF to disable
communications or “KROHNE”
to use the Krohne Bus Protocol.
Fct. 3.11.2 Address
Enter an address number
between 0 and 239. The
converter will only respond to
Bus messages which have a
matching address.
Fct. 3.11.3 Baudrate
Select the required
communications baudrate from
the following list:
1200, 2400, 4800, 9600, 19200
If the instrument is connected correctly, it should now communicate with an external master.
6. Transmission format
The data string has the following format:
syn ... syn STX < Data-Field > CS ETX
The transmission is initiated through an arbitrary number (at least 3) of Synchronisation bytes.
(Syn hex 16). This initialises the receiver to receive a data string. The string itself begins with
a start byte (STX, Hex 16) followed by the data field. The transmission is concluded with a
verification sum (Check sum, CS) and the end byte (ETX Hex 3).
The checksum byte is the sum [module 256 of all the bytes in the bus telegram (including
STX)] plus the number of bytes.
If one of the control characters (Syn, STX, ETX) appears in the data field or in the check sum,
then the symbol DLE (Hex 10) is placed in front of it. This is true for the symbol DLE itself.
These intentional prefix symbols are not entered in the check sum.
Examples (all values in hex code):
16 – 16 – 16 – 02 – AO – 01 – 6F – 07 – 1E – 03
Syn Syn Syn STX DEV ADR VER FKT CS ETX
16 – 16 – 16 – 02 – AO – 10 – 03 – 6F – 07 – 20 – 03
Syn m Syn m Syn m STX DEV DLE ADR VER FKT CS ETX
Address 03 represented as DL03
DLE is not included in checksum calculation