National Instruments 321645c-01 用户手册

Chapter 2

Function Reference — AI_Check

©

 National Instruments Corporation

2-3

NI-DAQ FRM for PC Compatibles

Returns the status of the analog input circuitry and an analog input reading if one is available. 

AI_Check

 is intended for use when A/D conversions are initiated by external pulses applied 

at the EXTCONV* pin or, if you are using the E Series devices, at the pin selected through 
the 

Select_Signal

 function; see 

DAQ_Config

 for information on enabling external 

conversions.

readingAvailable represents the status of the analog input circuitry. 

1:

NI-DAQ returns an A/D conversion result in reading. 

0:

No A/D conversion result is available.

reading is the integer in which NI-DAQ returns the 12-bit result of an A/D conversion. If the 
device is configured for unipolar operation, reading ranges from 0 to 4,095. If the device is 
configured for bipolar operation, reading ranges from –2,048 to +2,047. For devices with 
16-bit ADCs, reading ranges from 0 to 65,535 in unipolar operation, and –32,768 to +32,767 
in bipolar operation.

i16

assigned by configuration utility

i16

whether a reading is available

i16

integer result