LI-COR LI-7815, Instruction Manual

Page: 75 / 98

Setting the span calibration
Follow suitable spanning procedures, as described in Setting the span on page 6-3.
Plumb a span gas to the analyzer air inlet. Use a span gas balanced in air (do not use
a nitrogen-balanced gas).
1
To start a span calibration, enter:
mosquitto_pub -h 172.24.82.42 -t "licor/niobrara/system/CO2_Span"
-m "<CO2 tank in ppm>"
l mosquitto_pub
launches the application to publish (send to the instrument).
l
-h
specifies a host (the Trace Gas Analyzer) followed by the instrument IP
address
l 172.24.82.4x
is the IP address. You can also enter the host name. Both are
given on the instrument display.
l
-t
specifies that you want to subscribe to a topic.
l "licor/niobrara/system/CO2_Span"
is the topic and hierarchy for the LI-
7815.
l -m
specifies that you are sending a message from the command line.
l
"<CO2 tank in ppm>"
is the CO
2
concentration in PPM.
This initiates the span calibration in the LI-7815. The span is implemented imme-
diately.
2
To check if the span is complete, enter the command:
mosquitto_sub -h 172.24.82.42 -t "licor/niobrara/cfg/CO2_Span"
The instrument will reply with the span value (near 1) like
"1.00242"
3 Type
Ctrl + C
to stop the script.
Section 7. Communication with the MQTT protocol
7-5 Setting the span calibration