Filter
Top Products
Chapter 2 Function Reference — AO_Change_Parameter
NI-DAQ FRM for PC Compatibles 2-32
©
National Instruments Corporation
Output Enable
On some of the devices, you can disable the output even when the waveform generation is in
progress. You can use this feature to bring the output to a known level at any time.
On DAQArb 5411 devices, there is a relay just in front of the I/O connector. By disabling the
output, this relay switches so that the I/O connector output shorts to ground. The waveform
generation can still continue, but no signal appears at the I/O connector output. You can
enable or disable the output at any time.
To change the output enable setting, set paramID to
ND_OUTPUT_ENABLE.
Output Impedance
On some of the devices, you can select the output impedance to match the impedance of
the load.
Output impedance of 50 Ω is good for testing most of the devices. You can use output
impedance of 75 Ω for video testing. If you select an output impedance of 0 Ω, you should be
driving an unterminated load (that is, a load with a very high input impedance).
To change the output impedance setting, set paramID to
ND_IMPEDANCE.
Note
The values are set up in milliOhms (mΩ).
Table 2-9.
Parameter Setting Information for Output Enable
Device Type
Per Channel
Selection Possible
Legal Range
for paramValue
Default Setting
for paramValue
DAQArb AT-5411
DAQArb PCI-5411
4451 devices
4551 devices
Ye s ND_YES and
ND_NO
ND_NO
Table 2-10.
Parameter Setting Information for Output Impedance
Device Type
Per Channel
Selection Possible
Legal Range
for paramValue
Default Setting
for paramValue
DAQArb AT-5411
DAQArb PCI-5411
Yes 0, 50,000, and
75,000
50,000