LI-COR LI-7500, Инструкция по эксплуатации

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Appendix D
D-34 Appendix D
The Connection Protocol
Introduction
The purpose of this section is to describe the protocol used to establish communications with
the LI-7500 when it is operating in an “unknown” mode. That is, when the baud rate is not
known, nor are any other details about the instrument’s configuration.
Note: For simple data collection, the LI-7500 can be configured with the LI7500 Windows
program, and you will not have to deal with this protocol at all. If you wish to write your own
interface program or driver for the LI-7500, and you wish to get the LI-7500 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.
2.
The LI-7500 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:
3.
Send an ascii ACK character (decimal 06) to the LI-7500.
4.
Upon receipt of an ACK, the LI-7500 will output its current configuration, terminated
with a line feed (decimal 10). A sample configuration is shown below. After this is sent,
the LI-7500 will resume its normal operation, except it will remain at 9600 baud.