Agilent Technologies TwisTorr Medium Notice De Mode D'emploi page 234

17 Technical Information
RS 232/RS 485 Communication Description
NOTE
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<COM> (Command) = 0x30 to read the window, 0x31 to write into

the window
<DATA> = an alphanumeric ASCII string with the data to be

written into the window. In case of a reading command this field
is not present.
The field length is variable according to the data type as per the
following table:
Tab. 19
Data Type
Logic (L)
Numeric (N)
Alphanumeric (A)
<ETX> (End of transmission) = 0x03

<CRC> = XOR of all characters subsequent to <STX> and

including the <ETX> terminator. The value is hexadecimal coded
and indicated by two ASCII character.
The addressed SLAVE will respond with an ANSWER whose structure
depends from the MESSAGE type.
When the MESSAGE is a reading command, the SLAVE will respond
transmitting a string with the same structure of the MESSAGE.
Using the RS 485 interface, the message structure remains identical to the one used for
the RS 232 interface, the only difference being that the value assigned to the ADDRESS
<ADDR>.
TwisTorr Medium-TMP Rack Controller User Manual / 87-901-049-01 (B)
Field Length Valid
Characters
1 '0' = OFF
'1' = ON
6 '-', '.', '0' . . . '9' right
justified with '0'
Up to 14 from blank to '_' (ASCII)