Technical Information
RS 232/RS 485 communication description
Communication Protocol
The communication protocol is a MASTER/SLAVE type where:
Host = MASTER
Controller = SLAVE
The communication is performed in the following way:
1. the host (MASTER) send a MESSAGE + CRC to the controller
(SLAVE);
2. the controller answer with an ANSWER + CRC to the host.
The MESSAGE is a string with the following format:
<STX>+<ADDR>+<WIN>+<COM>+<DATA>+<ETX>+<CRC>
where:
NOTE
When a data is indicated between two quotes (‘...’) it means that the indicated
data is the corresponding ASCII character.
<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:
TwisTorr 304 FS on board Controller User Manual / 87-901-028-01 (C) 161/178
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