LI-COR LI7200RS, Instruction Manual

Page: 198 / 226

Appendix D. Configuration Grammar
In this case, we are setting the RS-232 output frequency to 10Hz, requesting that
Pressure be included in the output records, and that the bandwidth be 5 Hz. Notice
the 2 parentheses at the end of
(Pres TRUE))
. This is because
(Pres..)
and
(Freq..)
are
(RS232..)
commands, while
(BW..)
is not.
(BW..)
and
(RS232..)
are both
(Outputs..)
commands, however, and the “extra” parenthesis at the end
of
(BW 5))
signals the end of the
(Outputs..)
command.
An illegal command string would be
(BW 5)
because the
(BW...)
command is only recognized within the context of an
(Out-
puts...)
command.
The configuration grammar is case sensitive. That is,
(Outputs(BW 10))
will work,
while
(outputs(bw 10))
will not.
Who Sends What
Not all of the commands in the instrument grammar are really commands. Some
are designed to be used by the instrument to package outgoing data. The
(Data..)
command, or record, might look like this
(Data (CO2D 2.2083146e1)(H2OD 3.5485935e2)(Temp 2.5886261e1)(Pres
9.8157062e1))
This record is showing the latest values of CO
2
and H
2
O mole density (mmol m
-3
),
temperature (°C), and pressure (kPa). The fields present in a
(Data..)
record, and
how often they are output, is determined by the
(Outputs..)
command.
Once it has established communications with a host computer (discussed in the
next section), the instrument’s RS-232 communications is largely made up of out-
going
(Data..)
and
(Diagnostics..)
records. The only other type of records it
might send are
(Error..)
and
(Ack..)
. The
(Error..)
record is sent whenever
the instrument receives a command it cannot parse or recognize, and the
(Ack..)
record acknowledges a configuration change. It is also used to pass back the new
zero or span setting after a
(Calibrate..)
command.
Command Summary
In the following sections, some abbreviations are used:
D-2 LI-7200RS Enclosed CO₂/H₂O Analyzer