LI-COR LI7200RS, Instruction Manual

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Appendix D. Configuration Grammar
The Connection Protocol
The purpose of this section is to describe the protocol used to establish com-
munications with the instrument when it is operating in an “unknown” mode.
That is, when the baud rate is not known, nor are any other details about the instru-
ment’s configuration.
For simple data collection, the instrument can be configured with the PC software,
and you will not have to deal with this protocol at all. If you want to write your
own interface program or driver for the instrument, and you want to get the instru-
ment to send its configuration to you, then this protocol must be used.
Establishing Communications: Step by Step
1 Set a break condition on the RS-232 line. 500 ms should be sufficient.
The instrument will cease normal activity, change its baud rate to 9600 baud, and
begin to send ascii ENQ characters (decimal 05) at a rate of 2 Hz for up to 10
seconds. Before 10 seconds are up, the host should:
2 Send an ascii ACK character (decimal 06) to the instrument.
Upon receipt of an ACK, the instrument will output its current configuration, ter-
minated with a line feed (decimal 10). After this is sent, the instrument will
resume its normal operation, except it will remain at 9600 baud.
3 The host can then send the desired configuration changes, if any, to the instrument.
4
If the configuration change involves a baud rate change, the instrument will send its (Ack..) record
before changing baud rates.
D-22 LI-7200RS Enclosed CO₂/H₂O Analyzer