data acquisation

[xpzhan]

I want to use the example "Con Acq&Graph Voltage-Int Clk-Analog Start" to develop my daq system.

I will play sound and use sound signal as analog trigger. Once it receive the analog signal , it will start to do sampling. I am using USB-6218 , but it does't have a APFIO. Can I just change this default setting into any of my AI pin?  If I can not use this one, what I should do?

"APFI0 is the default Analog Trigger pin for M Series devices. 
Please refer to your device documentation for information
regarding valid Analog Triggers for your device."

Thanks

[jyang72211]

You can create a virtual channel, which would allow you to specific which physical channel is of interest (DAQmx >> Create Channel).  Then, you can feed the virtual channel to a triggering (DAQmx >> Create Channel).  I hope this help.

[xpzhan]

Thank you. jyang72211 ,

Do u mean to create a virtual channel to specific to a physical channel such as the analog for input the analog signal from the sound card?  But I heard USB-6218 doesnot support a analog triggering.

[Margaret F.]

Hello,

Thank you for posting to the NI Forums! You are correct, the USB-6218 does not support analog triggering. You will need to trigger your analog task off of a digital line. Please post back with any further questions.

[xpzhan]

Hi,Margaret ,

Do u have any suggestion for analog-digital triggering? Is there any simple way to do that? Thanks.

[aNIta B]

Hi Xpzhan,

         I would recommend taking a look at the example "Cont Acq&Graph Voltage-Analog SW Trigger.vi".  This can be found in the NI Example Finder»Browse»Hardware Input and Output»DAQmx» Analog Measurements»Voltage.  Though your device doesn't support analog triggering, this can be done through software.  Please let me know if this example won't work for you.  Have a great day, and happy programming!

aNItaB

Applications Engineer

National Instruments

[xpzhan]

Hi,aNIta B ,

If I use SW to trigger, the timing will be a problem. I want to trigger sampling when the sound play starts (or starts earlier exactly at a certain time).

[Margaret F.]

Hello,

It seems that you may need to look into a different DAQ device since this one cannot do hardware timing and software timing is too slow for your application. Please let me know if you have any further questions. Have a great day!

[xpzhan]

Hi, What's your recommendation? Any one in M series has this function? (analog triggering)

[A_Person]

Hi xpzhan:

The best way to find a DAQ device that suits your needs is to start at http://ni.com/daq.  From there, you can select devices with the specifications that you require.  This link already has M Series DAQ cards that support analog triggering presented.  You can then select your required form factor on the left.