Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 163)

daqCvtRtdConvert
Also See: daqCvtRtdSetup, daqCvtRtdSetupConvert
Format
daqCvtRtdConvert(counts, scans, temp, ntemp)
Purpose
daqCvtRtdConvert takes raw acquisiton data and converts it to a Celsius scale.
Parameter Summary
Parameter Type Description
counts PWORD Array of one or more scans of raw data as received from the device
scans DWORD Number of scans of raw data in counts parameter (number of pre-
trigger + post-trigger scans)
temp PSHORT Variable array to hold converted temperatures
ntemp DWORD Size of temperature array
Parameter Values
counts: valid pointer to an array of integer words (2 bytes) which contain the raw data to perform the RTD
conversion
scans: the number of scans to be converted from 1 to the size of the counts array (in scans)
temp: valid pointer to an array of single precision floating point (4 bytes) values which will store the
converted readings upon return from this command
ntemp: The value of the ntemp parameter should be equal to number of RTDs specified in setup times the
number of scans. If averaging is used, then ntemp should be equal to: [(the number of RTDs) *
scans * (the value of the avg parameter as set in the daqCvtRtdSetup function)]
Returns
DerrRtdNoSetup Setup was not called
DerrRtdTArraySize Temperature array is not large enough
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.
The daqCvtRtdConvert function takes acquired data from a resistance temperature detector (RTD) and
converts them to temperature readings in Celsius, with a resolution in tenths of a degree (0.1°C). Before this
commannd is executed, the RTD conversion should be configured using the daqCvtRtdSetup function.
The total number of data conversions [scans * (RTD channels per scan) * 4] must be less than 32,767.
For convenience, both setup and conversion can be performed at once by daqCvtRtdSetupConvert.
Programmer’s Manual 908494 Daq API Command Reference 4.3-37