Measurement Computing TempBook rev.3.0 - Manual (Page 103)

TempBook User’s Manual Enhanced API Programming Models (TempBook) 10-7
Temperature Acquisition Using One-Step Commands
This example demonstrates the Enhanced API’s high-level one-step routines to
read thermocouple input from the TempBook/66 device. These functions
combine scan sequencer setup, ADC data collection, and thermocouple
linearization. Functions used include:
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VBdaqSetDefaultHandler&(handler&)
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VBdaqGetDeviceCount&(deviceCount&)
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VBdaqGetDeviceList&(deviceList&, deviceProps)
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VBdaqOpen&(daqName$)
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VBdaqAdcSetDataFormat&(handle&, rawFormat&,
postProcFormat&)
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VBdaqAdcRd&(handle&,chan&, sample%, gain&, flags&)
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VBdaqAdcRdScan&( handle&,startChan&, endChan&, buf%,
gain&, flags&)
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VBdaqAdcRdScanN&( handle&,chan&, buf%, scanCount&,
triggerSource&, rising&, level%, freq!, gain&, flags&)
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VBdaqAdcRdN&(handle&,chan&, startChan&, endChan&, buf%,
scanCount&, triggerSource&, rising&, level%, freq!,
gain&, flags&)
•
VBdaqClose&(handle&,daqEvent&)
Const Scans& = 5000
Const Level% = 0
Const Rising& = 0
Const Start& = 0
Const End& = 0
Const Freq! = 6000.0
Const Gain& = TbkBiTypeJ&
Const Flags& = DafBipolar& + DafDifferential& + DafTcTypeJ&
Const Chans& = End& - Start&+1
Dim buf%(80), handle&, ret&, flags&
Dim I&, j&, deviceCount&, handle&, deviceIndex&
Dim temp%, temps%(Scans&*Chans&)
Dim sum!, totals!(Chans&)
Dim ret&
First, we need to open the TempBook/66 device. This example uses a device named “TempBook0”. The
device name must be a valid device name for a configured device.
handle& = VBdaqOpen&(“TempBook0”)
Set the raw data format to native and the post-processing data format to temperature in tenths of a degree C.
The post-processing data format controls the format of the data returned by the one-step acquisition
functions such as daqAdcRd. In this case, daqAdcRd returns temperatures rather than raw ADC
readings.
ret& = VBdaqAdcSetDataFormat& (handle&, DardfNative&, DappdfTenthsDegC&)
The following statement retrieves a single ADC sample from a type J thermocouple on channel Start&
and converts the reading to a temperature. The temperature is returned in the sample% parameter and is a
16-bit quantity which represents tenths of degrees C.
ret& = VBdaqAdcRd& (handle&, Start&, temp%, TbkBiTypeJ, Flags&)
Now the results for the single-sample read are displayed:
Print "Results of daqAdcRd for channel “, Start&, “: (single reading)"
Print "Temperature: “, temp/10.0, “C"
The next statement retrieves Scans&(5000) number of samples from a type J thermocouple on channel
Start&
and converts the readings to a single temperature using block averaging. The trigger source is set
to DatsImmediate& so the scans will be acquired immediately. Again, the temperatures are returned as
16-bit words representing tenths of degrees C.