Measurement Computing DAQFlex User Guide - Manual (Page 38)

DAQFlex Software User's Guide DAQFlex Message Reference – Programming messages – AI
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value The channel value.
Example "?AI{0}:VALUE"
 Get the calibrated A/D count of a specified channel.
Message
"?AI{ch}:VALUE"
Response "AI{ch}:VALUE=value"
ch The channel number.
value The calibrated A/D count.
Example "?AI{0}:VALUE"
 Get the A/D value in the specified format.
Message
"?AI{ch}:VALUE/{format}"
Response "AI{ch}:VALUE/{format}=value"
ch The channel number.
format The data format of the measurement:
 RAW: returns uncalibrated A/D counts
 VOLTS: returns a calibrated A/D voltage
 DEGC: returns a calibrated temperature value in °C
 DEGF: returns a calibrated temperature value in °F
 KELVIN: returns a calibrated temperature value in Kelvin
value The A/D value.
Example "?AI{0}:VALUE/DEGC"
Note This message is processed by the DAQFlex Software library, and is not sent to the
device.
Working with the CAL and SCALE properties
The ENABLE/DISABLE setting of the CAL and SCALE properties affect the kind of data that is returned:
 CAL=DISABLE, SCALE=DISABLE
If CAL and SCALE are both disabled, the data returned will be raw A/D integer values within the
range of 0 to 2 resolution -1 of the device. If the calibration factors are stored on the device and applied
to the data by the application software, the data range may be limited to well within these values.
 CAL=ENABLE, SCALE=DISABLE
When CAL is enabled and SCALE is disabled, the format of the analog data returned will depend on
the type of calibration implemented. If the calibration factors are stored on the device and applied
to the data by the application software, the data will be floating point values, not integer values,
and may exceed the theoretical limits and include negative values and values above 2 resolution -1.
 SCALE=ENABLE
When SCALE is enabled, scaled floating point values are returned. The limits of the data will depend
on the implementation of calibration, as described above. Data range limits may be a small
percentage less than or greater than the full scale range selected for devices for which the
calibration factors are stored on the device and applied to the data by the application software.