Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 177)

Returns
DerrTCE_TYPE Invalid thermocouple type
DerrTCE_PARAM Parameter out-of-range
DerrNoError No error
For more details on error messages refer to the Daq Error Table.
Function Usage
For all functions of the form daqCvt..., raw data to be converted must be unsigned
(i.e., the dafUnsigned value must be set using the daqAdcSetScan function).
For T/C and RTD conversion, users of Daq/2000 Series devices* and/or Daq PC Cards must
be sure that the main unit is using ten volt range gains settings, either unipolar (0 V to 10 V)
or bipolar (-5 V to +5 V).
See the “T/C Gains Settings” section in the daqCvtTCConvert function entry for the
appropriate settings.
* Daq/2000 Series devices include DaqBook/2000 Series, DaqScan/2000 Series, DaqLab/2000
Series, and DaqBoard/2000 Series devices.
Note: The following example assumes a CJC position of “0” and a Channel Zero position of “1.”
The position of these channels is device dependent. Refer to your device-specific hardware
documentation to determine the appropriate position of these channels for your application.
The daqCvtTCSetup function is used to set the values required to convert raw thermocouple (T/C) data to
data on a Celsius scale. It must be follwed with the daqCvtTCConvert function to actually convert the data.
For convenience, both setup and conversion can be performed at once by daqCvtTCSetupConvert. All of
the T/C conversion functions (i.e., functions of the form daqCvtTC…)can convert several consecutive scans
of data in a single invocation.
The cjcPosition parameter determines the positon of the CJC reading in the scan group. Each scan of
temperature data must include a reading of the CJC signal on the expansion board to which the thermocouples
are attached. If zero compensation is being used, then the first two scans in each group are reserved for zero
compensation data, and the CJC scan must follow immediately thereafter. The illustration below shows a how
a typical T/C acquisition with zero compensation would collect data:
Programmer’s Manual 908494 Daq API Command Reference 4.3-51