output 5v signal using PCI-6251

[kirkland4]

I have an actuator that is enabled when hit with a 5v signal. I'm using PCI-6251 card and an SCB-68 connector block.

If I hook up the actuator the the +5v slot in the connector block it does work, however this is useless as I cannot control the enabling/disabling of the actuator with labview.

I want to use the DAQ card to output a 5v signal every once in a while. Right now, I have set up a task in NI-MAX to attempt to get the signal talking but it isnt working. I am forced to oscillate my signal between 4.99 and 5v (as it appears I cannot keep a constant voltage), but even then, my voltmeter does not read any voltage coming out of the connector block.

Has anyone had experience with this and may know what i'm doing wrong?

Thanks

[AnalogKid2DigitalMan]

What pin numbers on the block are you attempting to use? Do you know how much current the actuator requires? I presume that it works when connected to +5V line, but not when connecting to an actual ouput (analog or digital) since those lines cannot supply enough current to drive the actuator.

[kirkland4]

I'm not sure of the pin numbers exactly, but I use the AOCH1 and a GND.

I believe that the actuator has its own power supply, the 5 volts simply acts as a trigger.

[Brian F.]

Hello kirkland. 

Thank you for contacting National Instruments

From what I am reading, you would like to toggle voltage between 5 volts and 0 volts at your discretion to power an actuator.  I would recommend using a digital line instead of an analog output to control your actuator for this application.  Since digital lines are by default 5 volts when high and 0 volts when low, it will make for easier development on your end.  I actually created a quick example program in LabVIEW 8.2 that can do exactly what you desire.  I used the exact same hardware you have (PCI-6251 and SCB-68) to test this program.  The program outputs either 5 volts or 0 volts on port 0, line 0.  The level of the voltage can be changed by the user by simply clicking on the boolean control "data" on the front panel of this VI.  Port 0, line 0 corresponds to pin 52 on the 6251 and thus pin 52 on the SCB-68 since the SCB-68 maps 1 to 1 on all pins of the 6251.  So, if you connect a wire to pin 52 and one to pin 53 (digital ground), you should measure 5 Volts between these two pins when the program is running and the boolean control is true.  If you change the boolean control to false (off), 0 volts will be measured between pins 52 and 53.   

Let me know if this answers your question and helps your application be successful.  If my statements require additional clarification or spur new questions, please do not hesitate to ask! 

Have a great day!

Brian F
Applications Engineer
National Instruments

[kirkland4]

Brian,

Thanks for making the VI, but is there any way you can save it as version 8? I have yet to upgrade to 8.2

Thanks

[Brian F.]

Hi kirkland. 

I have saved the VI attached above to be compatible with LabVIEW 8.0.  Let me know how it goes!

[greentea2]

Hello,

I have tried the program above on the 6009 oem but it does not work. I connect the positive lead of a voltmeter to P0.0 and negative lead of the voltmeter to D GND. Before I ran the program, the voltmeter readout was -5.06 V and does not change even though I toggle the "data" button on the front panel.  I am trying to output a 5V signal to control a relay and am not sure why the program isn't working. Please help.

[Wee-Bey]

Can you check if you're writing to the correct channels? That can be a problem when using other code.