National Instruments 321645c-01 用户手册

Chapter 2

Function Reference — AO_Change_Parameter

©

 National Instruments Corporation

2-31

NI-DAQ FRM for PC Compatibles

To change the FIFO transfer count, set paramID to 

ND_FIFO_TRANSFER_COUNT

 and use 

paramValue to pass in a 32-bit integer.

Set channel to one of the channel numbers in your waveform group. For example, if you have 
configured group 1 to contain channels 0 and 1, you can set channel to 0 or 1.

You can ground the reference that the analog output channels use, which causes the output 
voltage to remain at 0 V, regardless of the value you write to the channel.

To change the grounding of the DAC Reference, set paramID to 

ND_GROUND_DAC_REFERENCE

, and set paramValue to either 

ND_YES

, or 

ND_NO

. The effect 

is immediate. Also, grounding the DAC reference on one channel has the effect of grounding 
it for both channels, so you can specify either 0 or 1 for channel number.

Some devices have a lowpass analog filter after the DAC. You can switch this filter ON or 
OFF. By switching this filter OFF, the analog lowpass filter stage is bypassed. To change the 
digital filter setting, set paramID to 

ND_ANALOG_FILTER

.

Some devices have a lowpass digital filter before the DAC. You can switch this filter ON or 
OFF. By switching this filter OFF, the digital lowpass filter stage is bypassed.

To change the digital filter setting, set paramID to 

ND_DIGITAL_FILTER

.

Table 2-7.  Parameter Setting Information for the Analog Filter

DAQArb AT-5411 
DAQArb PCI-5411

Yes

ND_ON

 and 

ND_OFF

ND_ON

Table 2-8.  Parameter Setting Information for the Digital Filter

DAQArb AT-5411 
DAQArb PCI-5411

Yes

ND_ON

 and 

ND_OFF

ND_ON