National Instruments 321645c-01

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 e xample, if you ha ve

configured group 1 to contain channels 0 and 1, you can set channel to 0 or 1.

Note This option is valid only for PCI E Series devices.

Ground DAC Reference

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 groundi ng

it for both channels, so you can specify either 0 or 1 for channel number.

Note This option is valid only for PCI E Series devices.

Analog Filter

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. T o change the

digital filter setting, set paramID to ND_ANALOG_FILTER.

Digital 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

Device Type Per Channel

Selection Possible Legal Range

for paramValue Default Setting

for paramValue

DAQArb AT-5411

DAQArb PCI-5411 Yes ND_ON and

ND_OFF ND_ON