Rs 232/Rs 485 Communication Description; Communication Format; Communication Protocol - Agilent Technologies TwisTorr Medium-TMP Rack User Manual

Technical Information

RS 232/RS 485 Communication Description

Both the RS 232 and the RS 485 interfaces are available on the connector P2.
The communication protocol is the same (see the structure below), but only the RS
485 manages the address field. Therefore, to enable the RS 485 is necessary to
select the type of communication as well as the device address by means of the
serial communication software.

Communication Format

8 data bit

no parity

1 stop bit

baud rate: 600 / 1200 / 2400 / 4800 / 9600 / 19200 / 38400 programmable

(default setting: 9600).

Communication Protocol

The communication protocol is a MASTER/SLAVE type where:
Host = MASTER

Controller = SLAVE

The communication is performed in the following way:
the host (MASTER) send a message + CRC to the controller (SLAVE);

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:
When a data is indicated between two quotes ('...') it means that the indicated data
NOTE
is the corresponding ASCII character.
168 Agilent TwisTorr Medium-TMP Rack Controller User Manual