Bronkhorst RS232 interface - Manual (Page 12)

BRONKHORST ®
Page 12 RS232 interface 9.17.027
3.3.3 RS232 ASCII protocol
An ASCII protocol is used on the existing RS232‐HOST. To be compatible with existing driver software the ASCII
protocol is available.
A basic data link message is coded in ASCII as follows:
length node data
: len1 len2 node1 node2 data1 data2 CR
Byte Explanation
: Initial character (semicolon)
Len1, len2 Length of message including the node address in bytes, so (len1, len2) is
the basic message length +1.
node1, node2 node address of destination (PC to HOST)
node address of source (HOST to PC)
data1, data2 message field
CR termination character
All bytes (except the initial and termination character) are converted from 1 binary byte to 2 hexadecimal bytes in
ASCII representation.
Example: binary data byte 0x2A ‐‐> hexadecimal ASCII characters 0x32, 0x41.
A special message type is used to pass error messages from the HOST to the PC. Its structure is as follows:
0x01 error
: 0x30 0x31 error1 error2 CR

Byte Explanation
: initial character
0x30, 0x31 length of the message (1 byte)
error error code, two digit HEX number
CR termination character

The error code can have the following values:
Value Meaning
3 propar protocol error
4 propar protocol error (or CRC error)
5 destination node address rejected
9 response message timeout
1,2,8 general error