From Friday, April 19th (11:00 PM CDT) through Saturday, April 20th (2:00 PM CDT), 2024, ni.com will undergo system upgrades that may result in temporary service interruption.
We appreciate your patience as we improve our online experience.
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for
Topic Options
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page
Newbie question.
JackMetcalfe
Member
03-19-2001 05:09 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Can I control the voltage being output by the PCI-4451?
If I can control the voltage are there any sample apps that illustrate how?
What is 'update rate' in the Measurement and Automation explorer and why does the output voltage fluctuate based on it? I have a PCI-4451 connected to a BNC-2140 and have been unable to control the output voltage. I have the output from the BNC-2140 going into an osciliscope to verify my waveform's amplitude and frequency. Using the Test Panel in Measurement and Automation explorer I have been able to generate a sine wave that went from about -9 to +9 volts at an 'update rate' of 15 kHz - I had requested voltage from -10 to +10. When I reduced the 'update rate' the voltage dropped to a measured range of
-1 to +1.
When I tried controlling the voltage in software using the ActiveX controls I was not able to impact the voltage at all.
Thanks in advance,
Jack Metcalfe
03-19-2001 05:54 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Ooops! I forgot to multiple my sin() result by the desired voltage. Never mind unless you can explain the measurement and automation explorer behavior.
Jack Metcalfe
Jack Metcalfe
Bryan F
Member
03-21-2001 12:51 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Hello Jack,
The "update rate" parameter in Measurement and Automation Explorer determines how often the 4451 board updates the voltage on its analog output line. This value is not equal to the physical frequency of the analog sine output, but it is directly proportional to it.
I tried a wide range of update rates using the 4451 attached to an analog oscilloscope and I did not see any change in amplitude at lower update rates. It sounds like very low-frequency signals may be experiencing some filtering in your circuit. You can expect this if you are feeding into an oscilloscope set for AC coupling.
There are several examples available in LabVIEW, ComponentWorks, and LabWINDOW/CVI for programminmg analog output. In LabVIEW and ComponentWorks, you can use most hardwar
e-timed analog output examples for your DSA board. If you are programming in CVI, I would suggest taking a look at our example program available in the Developer Zone (search under "DSA" and "output").
If you are still running into problems, please call in for technical support or submit an email support request at:
www.ni.com/support/ask.
Good luck!
Bryan
The "update rate" parameter in Measurement and Automation Explorer determines how often the 4451 board updates the voltage on its analog output line. This value is not equal to the physical frequency of the analog sine output, but it is directly proportional to it.
I tried a wide range of update rates using the 4451 attached to an analog oscilloscope and I did not see any change in amplitude at lower update rates. It sounds like very low-frequency signals may be experiencing some filtering in your circuit. You can expect this if you are feeding into an oscilloscope set for AC coupling.
There are several examples available in LabVIEW, ComponentWorks, and LabWINDOW/CVI for programminmg analog output. In LabVIEW and ComponentWorks, you can use most hardwar
e-timed analog output examples for your DSA board. If you are programming in CVI, I would suggest taking a look at our example program available in the Developer Zone (search under "DSA" and "output").
If you are still running into problems, please call in for technical support or submit an email support request at:
www.ni.com/support/ask.
Good luck!
Bryan
