daq create channel

[oldpan]

Hi all,

Here is my story - I have a daq application. I basically use the cont acq&graph voltage.VI (in the examples coming with LV) to do the acquisition, but instead of one channel, I have like 20. What's wrong with this?:Nothing, the application goes well. But after this, I run the same application on another computer, with the settings all right, and I get problems seemingly just because I have too many channels. On this second computer, when I leave only one channel, the daq stars aquiring. From this I get 2 questions:
1. Why the same application runs well on one computer and works bad on another?
2. Why does the application, copied on the second computer, runs well for one channel and pops up an error when I switch to more channels?
If you can have some answer for this, I appreciate it a lot.

Thank you,
Dana

[oldpan]

Hello,
I come with the answers of my question:
1.THe channels I have are a constant, and since I tranferred the program from one computer to another, a computer names the device differently: for one, the daq was seen as Dev1, and for the 2nd, Dev2.
2. To test the one channel/N channels behavior, I used the constant form an example from the host computer, which previously captured the right label for the device, and the constant with wrong label from the other computer.

Best wishes,
Dana

[kmous]

Hi dana , well this example was with LV i think , any ways i need a VI that works with 4 channels , would you mind showing me ur VI ...it is a small part from my project !!!! so let me know plz Thank you
kmous83@hotmail.com

[Dennis_Knutson]

The shipping examples and the DAQ Assistant work with multiple channels. You just have to select them. With a physical channel control, right click on the arrow on the right side and select Browse. You will get a list of available devices and channels. To select multiple channels, use Crtl-Click or Shift-Click to select more than one. The same option is avaliable in the DAQ Assistant. You could also simply enter in your channel list with the correct syntax. For consecutive channels, use for example Dev1/ai0:3. For non-consecutive channels, use for example Dev1/ai0,Dev1/ai2.

p.s. It's also not a good idea to post an email address in a public forum. All question are answered in the forum and all you will get is spam.

Message Edited by Dennis Knutson on 06-13-2008 08:09 AM

[kmous]

thank you i will try to do that 🙂 u are right about the email thx 🙂
I got a question : how can i insert Daqmx to create channels.vi function ? i could not find ?
thank you

[Dennis_Knutson]

I'm not sure I understand what you mean. The DAQmx Create Channel function is on the Measurement I/O>DAQmx palette. If you want a physical channel constant, the simplest way is to just right click on the physcial channel input of this and select 'Create>Constant'. If you want a front panel control, select 'Create>Control'. A block diagram constant can also be placed with the Measurement i/O>DAQmx>Advanced>I/O Constants palette. A front panel control can be placed with the I/O>DAQmx Name Controls palette.

[kmous]

if u look at Acq Thermocouple Sample.vi u will see DaqMx for AI Temp TC where can i find it ?

[Dennis_Knutson]

It is the DAQmx Create Channel. See the little box with a down arrow below the DAQmx functions? Click it to select the type of channel you want.

This is LabVIEW/DAQmx basics. See http://www.ni.com/academic/lv_training/how_learn_lv.htm and http://zone.ni.com/devzone/cda/tut/p/id/5434. You should also have the context help window open at all times and be using it.

Message Edited by Dennis Knutson on 06-13-2008 08:41 AM

[kmous]

Thank you man i am learning alot from you 🙂 really many thx