Agilent Technologies TwisTorr 84 FS AG X3508-64001 Bedienungshandbuch Seite 238

17 Technical Information
Letter Protocol Description
<STX> (Start of transmission) = 0x02
<ADDR> (Unit address) = 0x80 (for RS 232)
<ADDR> (Unit address) = 0x80 + device number (0 to 31)
(for RS 485)
<WIN> (Window) = a string of 3 numeric character indicating the
window number (from '000' to '999'); for the meaning of each
window see the relevant paragraph.
<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. 14
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
NOTE
used for the RS 232 interface, the only difference being that the value assigned
to the ADDRESS <ADDR>
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Field Length
1
6
10
TwisTorr 84 FS AG Rack Controller User Manual / 87-901-037-01 (D)
Valid Characters
'0' = OFF
'1' = ON
'-', '.', '0' . . . '9' right justified with '0'
from blank to '_' (ASCII)