TGA (TGA100A, TGA200, or TGA200A)
The TGA instruction is used to measure a TGA100A, TGA200, or TGA200A trace gas analyzer system. It can also be used to measure a TGA100 with an upgraded CPU module.
Syntax
TGA ( Dest, SDMAddress, DataList, ScanMode )
Example
Following is an example program for measuring the TGA trace gas analyzer.
'Declare Public Variables
Public RefTemp, batt_volt
Public TGAData(31) 'destination array for TGA data
Alias TGAData(1) = ConcA
Alias TGAData(2) = ConcB
Alias TGAData(3) = ConcC
Alias TGAData(4) = TGAStatus
Alias TGAData(5) = TGApressure
Alias TGAData(6) = LaserTemp
Alias TGAData(7) = DCCurrentA
Alias TGAData(8) = DCCurrentB
Alias TGAData(9) = DCCurrentC
Alias TGAData(10) = TGAAnalog1
Alias TGAData(11) = TGATemp1
Alias TGAData(12) = TGATemp2
Alias TGAData(13) = LaserHeater
Alias TGAData(14) = RefDetSignalA
Alias TGAData(15) = RefDetSignalB
Alias TGAData(16) = RefDetSignalC
Alias TGAData(17) = RefDetTransA
Alias TGAData(18) = RefDetTransB
Alias TGAData(19) = RefDetTransC
Alias TGAData(20) = RefDetTemp
Alias TGAData(21) = RefDetCooler
Alias TGAData(22) = RefDetGainOffset
Alias TGAData(23) = SmpDetSignalA
Alias TGAData(24) = SmpDetSignalB
Alias TGAData(25) = SmpDetSignalC
Alias TGAData(26) = SmpDetTransA
Alias TGAData(27) = SmpDetTransB
Alias TGAData(28) = SmpDetTransC
Alias TGAData(29) = SmpDetTemp
Alias TGAData(30) = SmpDetCooler
Alias TGAData(31) = SmpDetGainOffset
'Declare Constants for TGA
const TGA_SDMAddress = 0
const TGA_DataList = 4
const TGA_ScanMode = 3
'Define Data Tables
DataTable (Test,1,-1)
DataInterval (0,15,Sec,10)
Minimum (1,batt_volt,FP2,0,False)
Sample (1,RefTemp,FP2)
Sample (31,TGAData,IEEE4) 'store all TGA data
EndTable
'Main Program
BeginProg
Scan (1,Sec,0,0)
Battery (Batt_volt)
'Enter other measurement instructions
TGA(TGAData, TGA_SDMAddress, TGA_DataList, TGA_ScanMode)'get TGA data
'Call Output Tables
CallTable Test
NextScan
EndProg
Parameters
Dest
The array in which to store the results of the measurement. The length of the input variable array depends on the values of parameters DataList and ScanMode.
Type: Variable Array
SDMAddress (Address of Device)
Defines the address of the device with which to communicate. Valid SDM 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.
DataList
Specifies the data to be retrieved from the sensor. If DataList = 1, only concentration and status are returned. If DataList = 2, then laser temperature, pressure, and DC Current are returned in addition to concentration and status. If DataList = 3, then the TGA analog signal 1 and TGA temperatures are also returned. If DataList = 4, then all data except DutyCycle1 and DutyCycle2 are returned. If DataList = 5, then all data are returned. See the list below for complete information:
| Name | Description | DataList | ScanMode |
|---|---|---|---|
| ConcA | Trace gas concentration measured in ramp A (ppmv) | 1 | 1 |
| ConcB | Trace gas concentration measured in ramp B (ppmv) | 1 | 2 |
| ConcC | Trace gas concentration measured in ramp C (ppmv) | 1 | 3 |
| TGAStatus | Status flags: see table below | 1 | 1 |
| TGAPressure | Pressure in the analyzer vacuum manifold (mb) | 2 | 1 |
| LaserTemp | emperature of the laser mounting plate (K) | 2 | 1 |
| DCCurrentA | Laser DC current for ramp A (mA) | 2 | 1 |
| DCCurrentB | Laser DC current for ramp B (mA) | 2 | 2 |
| DCCurrentC | Laser DC current for ramp C (mA) | 2 | 3 |
| TGAAnalog1 | TGA Analog Channel 1 voltage (V) | 3 | 1 |
| TGATemp1 | Temperature of TGA detector mounting plate (°C) | 3 | 1 |
| TGATemp2 | Temperature of TGA dewar mounting plate (°C)> | 3 | 1 |
| LaserHeater | Voltage applied to the heater on the laser mounting plate to maintain the laser at the specified temperature (V) | 4 | 1 |
| RefDetSignalA | Reference detector signal at the center of the spectral scan for ramp A (mV) | 4 | 1 |
| RefDetSignalB | Reference detector signal at the center of the spectral scan for ramp B (mV) | 4 | 2 |
| RefDetSignalC | Reference detector signal at the center of the spectral scan for ramp C (mV) | 4 | 3 |
| RefDetTransA | Reference detector transmittance at the center of the spectral scan for ramp A (%) | 4 | 1 |
| RefDetTransB | Reference detector transmittance at the center of the spectral scan for ramp B (%) | 4 | 2 |
| RefDetTransC | Reference detector transmittance at the center of the spectral scan for ramp C (%) | 4 | 3 |
| RefDetTemp | Reference detector temperature (°C) | 4 | 1 |
| RefDetCoole | Current applied to the thermoelectric cooler to maintain the reference detector at its specified temperature (arb) | 4 | 1 |
| RetDetGainOffset | Gain and offset settings for the reference detector preamplifier (arb) | 4 | 1 |
| mpDetSignalA | Sample detector signal at the center of the spectral scan for ramp A (mV) | 4 | 1 |
| SmpDetSignalB | Sample detector signal at the center of the spectral scan for ramp B (mV) | 4 | 2 |
| SmpDetSignalC | Sample detector signal at the center of the spectral scan for ramp C (mV) | 4 | 3 |
| SmpDetTransA | Sample detector transmittance at the center of the spectral scan for ramp A (%) | 4 | 1 |
| SmpDetTransB | Sample detector transmittance at the center of the spectral scan for ramp B (%) | 4 | 2 |
| SmpDetTransC | Sample detector transmittance at the center of the spectral scan for ramp C (%) | 4 | 3 |
| SmpDetTemp | Sample detector temperature (°C) | 4 | 1 |
| SmpDetCooler | Current applied to the thermoelectric cooler to maintain the sample detector at its specified temperature (arb) | 4 | 1 |
| SmpDetGainOffset | Gain and offset settings for the sample detector preamplifier (arb) | 4 | 1 |
| DutyCycle1 | Duty cycle for the TGA heater 1 | 5 | 1 |
| DutyCycle2 | Duty cycle for the TGA heaster 2 | 5 | 1 |
Status Flags - The TGAStatus value gives an indication of the overall status of the TGA. A value of zero indicates a normal condition. A nonzero value indicates one or more of the bits are set. The meaning of each of the bits is given below.
|
Bit |
Decimal Value |
Description |
|---|---|---|
| 0 | 1 | Line Lock for ramp A is OFF |
| 1 | 2 | Line Lock for ramp B is OFF |
| 2 | 4 | Line Lock for ramp C is OFF |
| 3 | 8 | Sample detector signal exceeded input range |
| 4 | 16 | Reference detector signal exceeded input range |
| 5 | 32 | Sample detector temperature is outside its specified range |
| 6 | 64 | Reference detector temperature is outside its specified range |
| 7 | 128 | Laser temperature outside its specified range |
| 8 | 256 | Pressure is above is upper limit |
Type: Constant
ScanMode
Specifies the number of values to be retrieved for scan-specific data. Normally the ScanMode parameter corresponds to the TGA100A "number of ramps" parameter that specifies how many absorption lines are being measured. If ScanMode is set to a lower number than the TGA100A "number of ramps" parameter, the data for ramp B and/or C will not be retrieved from the TGA100A. If ScanMode is set to a higher number than the TGA100A "number of ramps" parameter, the TGA100A will return zero for the ramp B and/or C values.
Type: Constant