To write a waveform to two analog outputs of DAQ(USB-6215)

[dataacq]

Hello,

          I am using USB-6215 which has two analog outputs and need to send the same waveform through the two analog outputs of my DAQ. simultaneously. actually, i have a text file consisting of a code word(please see the attatchment) with dt, freq and appended 0's in the first column and remaining columns contain the the codeword. Withe the help of dt, rate and data i made a waveform with the build waveform VI.I am able to write this wavefrom through one analog output A01 right now. i want to know how i could write the same waveform to another analog out AO0 simultaneously. i am using an external trigger source through PFI0 in  for triggering. right now i am using the DAQmx write.vi ( analog 1D DBL 1 channel N samples) and DAQmx create virtual channel.vi with dev1/ao1 as the physical channel. for more information i am attatching the program as well as the text file. please see the page2 of my case structure in the VI attatched.

                                                                                Thank you.

regards,

Raja

[Steve_B]

Hi Raja,

You will be able to include an additional channel into your task in a manner similar to entering "Dev1/ai0:1" into the channel input. This will include channels 0-1 into your task. You will have to be sure that you write the appropriate data for both channels (for instance a 1D Waveform may be suitable). This will provide the functionality you were looking for.

[dataacq · Accepted solution]

Hi Steve,

               its working now. I changed the DAQmx write instance to analog waveform N channel N samples. still i have only one waveform now. How could i make it as two as it(DAQmx write ) will not accept single waveform as input as the number of channels in task will now be 2 where as the waveform has one output.

regards,

raja

[Dennis_Knutson]

It's really pretty basic. If you have a single waveform or a 1D DBL array wired to DAQmx Write 1Ch NSamp, then you need to wire a 1D waveform array or 2D DBL array to a DAQmx Write NCh NSamp.

[dataacq]

Hello Steve,

                    Hope you remember me. I am trying to read the samples(voltage) from my DAQ board(NI-USB 6215) by running the example vi ( Cont Acq&Graph Voltage-int clk.vi). I am getting a negative 10 volts constantly for a period of time before it actually starts reading my samples and sometimes gives a continous positive 5 volts . please see the text file attached.I am actually writing samples of +0.25V and -0.25V to the DAQ.

[Steve_B]

Hi Raja,

What type of connection are you making to the USB-6215 and what type of measurement have you configured? It seems as if the measurement may be floating for a period of time and settling back down. If you open Measurement and Automation Explorer you will be able to find your device listed under Devices and Interfaces>>NI-DAQmx Devices. You can right-click on the device and choose to open Test Panels. This interface will allow you to see the voltage that is being read at your selected input. Do you see the same issue here? You may need to change the input configuration to match your connection type. Is this issue repeatable for multiple iterations of your program?