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5
Technical Information
RS 232 Communication Description
RS 232 Communication Description
The RS 232 interface is available on the connector P2.
Communication Format
8 data bit
no parity
1 stop bit
baud rate: 600/1200/2400/4800/9600 programmable
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:
When a data is indicated between two quotes (‘...’) it means that the indicated
NOTE
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)
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PHD-4 Portable Helium Detector User Manual / 87-900-120-01 (F )
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