PC to CPU:

'STX' 'ADR' 'a' channelno_value 'CHK' 'ETX''

'a'
ASCII-Code 0x61 OR 0x80 = 0xE1
channelno
one byte in ASCII OR 0x80
_
blank = 0x20 OR 0x80 = 0xA0
value
format XXX.X (for negative values -XX.X) per byte in ASCII OR 0x80
Remark:
If several channels are available, each one must be set separately.
Example:
ADR = 1, channelno = 0 (temperature channel), value = -14.5°C
String =
0x02 0x81 0xE1 0xB0 0xA0 0xAD 0xB1 0xB4 0xAE 0xB5 0xC3 0x03 (12 Bytes)
CPU to PC

'STX' 'ADR' 'a' 'CHK' 'ETX'

'a'
ASCII-Code 0x61 OR 0x80 = 0xE1