DC signal using Counter Output Channel

[bilog1198]

Hello,

I currently have a program that will output a digital signal. I used the Example Gen Dig Pulse Train and placed it in a case structure so it will run when it is true. When the case is false, I want to output a DC signal through the default output channel that the counter signal comes from (in my case CTR0 0 Out). I am not sure how to do this? Would using DAQ assist or DAQmx be better for this?

Thanks,

bilog1198

[aNIta B]

Hi Bilog1198,

        Can you please clarify what you're trying to do, from the sound of it you're not going to be able to output a DC voltage on a counter.  What device are you using?  Is there a reason you can't simply output on a PFI line?  Thanks!

Message Edited by aNIta B on 06-17-2009 05:57 PM

[bilog1198]

Thank you for your response AnitaB. We are using a NI PCI- 6251. We are needing to send a digital signal to a polygon scanning mirror. We are outputing a digital pulse using a counter signal (using Daqmx) when the case structure is true. When the case is false, we wanted to send a DC signal to the mirror so it would stop scanning, but we realized we didn't know how we were going to send this signal to CTR0. Should we re-route the counter signal to a PFI line? How would be go about doing this? Do you have any suggestions to do this in a better way?

Thanks,

Bilog1198

[HeatherBaker]

Good morning Bilog1198,

You can output your DC signal on the same counter line, which is PFI 12 for counter 0.  Be sure to clear the task at the end of the True case structure to prevent resources reserved.  Take a look at the Write Dig Channel example in the LabVIEW Example Finder.

[bilog1198]

Hello h_baker,

We are using a SCB-68 for E series devices and we only have pins up to PFI 9. I rerouted the signal from CTR 0 to PFI 9/CTR 0 GATE. Do you think I would be able to route the DC signal to this terminal?

Thanks,

Bilog1198

[aNIta B]

Hi Bilog,

      When you say "Do you think I would be able to route the DC signal to this terminal?" , does "this" refer to PFI 9/CTR 0 GATE?  Assuming it does, you would be able to route your DC signal to that line.  However, as Heather noted, if you are doing a coutner output task in one case of a case structure, you would need to clear the task before going into your next case where you are using the same line for your DC output.  Happy programming!

[bilog1198]

Thanks for yall's help. I will try that and see how it works!