LI7200 (Measure LI-7200 Gas Analyzer)

The LI7200 instruction is used to measure an LI-7200 LI-COR Closed Path CO2 and H2O gas analyzer.

Syntax

LI7200 ( Dest, Reps, SDMAddress, LI7200Cmd )

The following example shows the use of the LI7200 instruction.

Public wind(5)
Public irga(5)
Alias wind(1) = Ux
Alias wind(2) = Uy
Alias wind(3) = Uz
Alias wind(4) = Ts
Alias wind(5) = sonic_diag
Alias irga(1) = CO2
Alias irga(2) = H2O
Alias irga(3) = agc
Alias irga(4) = irga_cell_tmpr
Alias irga(5) = irga_cell_press
Units wind = m/s
Units Ts = C
Units sonic_diag = arb
Units CO2 = umol/mol
Units H2O = mmol/mol
Units agc = arb
Units irga_cell_tmpr = C
Units irga_cell_press = kPa

DataTable (ts_data,TRUE,-1)
  DataInterval (0,0,mSec,10)
  CardOut (0,-1)
  Sample (5,Ux,IEEE4)
  Sample (5,CO2,IEEE4)
EndTable

'Main Program 
BeginProg
  SDMSpeed (30)
  Scan (50,mSec,3,0)
    CSAT3 (Ux,1,3,91,20)
    LI7200(CO2,1,7,5) 
    CallTable ts_data
  NextScan
EndProg

Remarks

The LI7200 instruction is used to communicate with the LI-7200 via SDM.

Parameters

Destination

The input variable name in which to store the data from each LI-7200 associated with this instruction. The length of the input variable array will depend on the number of repetitions and on the selected command.

Command Input Variable length per LI-7200
0 2
1 5
2 10
3 12
4 10
5 5
6 1
7 5

Type: Array

Reps

Determines the number of gas analyzers with which to communicate using this instruction. The gas analyzers must have sequential SDM addresses if the Reps parameter is greater than 1.

Type: Constant integer (or expression that evaluates as a constant).

SDMAddress (Address of Device)

Defines the address of the device with which to communicate. Valid ClosedSDM Synchronous Device for Measurement. A processor-based peripheral device or sensor that communicates with the datalogger via hardwire over a short distance using a protocol proprietary to Campbell Scientific. addresses are 0 through 14. Address 15 is reserved for the SDMTrigger instruction.

Some SDM instructions support repetitions. If a Reps parameter is present and it is greater than 1, the data logger will increment the SDM address used in the instruction for each subsequent device with which it communicates.

LI7200Cmd

Requests the data to be retrieved from the sensor. The command is sent first to the device specified by the SDMAddress parameter. If the Reps parameter is greater than 1, subsequent LI-7200s will be issued the command with each repetition. The results for the command will be returned in the array specified by the Dest parameter. A numeric code is entered to request the data:

Code Description
0 CO2 dry (μmol/mol), H2O dry (mmol/mol)
1 CO2 (mmol/m^3), H2O (mmol/m), Ptotal (kPa), Tin (C), Tout (C)
2 CO2 dry (μmol/mol), H2O dry (mmol/mol), CO2 (mmol/m^3), H2O (mmol/m^3), AGC (%), Ptotal (kPa), Tin (C), Tout (C), Tavg_Tin_Tout (C), Aux channel #1
3 CO2 dry (μmol/mol), H2O dry (mmol/mol), CO2 (mmol/m^3), H2O (mmol/m^3), AGC (%), PTotal (kPa), Tin (C), Tout (C), Aux channel #1, Aux channel #2, Aux channel #3, Aux channel #4
4 CO2 (mmol/m^3), H2O (mmol/m^3), CO2 absorptance, H2O absorptance, AGC (%), Ptotal (kPa), Tin (C), Tout (C), Block Temperature (C), diagnostic
5 CO2 dry (μmol/mol), H2O dry (mmol/mol), AGC (%), Tavg_Tin_Tout (C), Ptotal (kPa)
6 Diagnostic
7 Get CO2 dry (μmol/mol), H2O dry (mmol/mol), AGC (%), Ptotal (kPa), and Tavg_Tin_Tout (C) after an SDMTrigger instruction