Sending same data through two TXs

[dalexander98]

Hi,

I've been struggling sending the same data through two different TXs, one on channel 0 and one channel 1, the VI works for a single TX but when I change the "niUSRP Write Tx Data" block to 2D complex double it doesn't take the data in anymore and displays "you have connected two arrays of different dimensions". I was hoping the data in would just be sent out on both channels. I have tried fixing the problem using arrays and the channel writer both to no avail, but it is possible I have been using them wrong.

I believe I just need an in-line function to send the data duplicated side-by-side so that each channel has a stream of data to send, but I am just unsure how to do this.

Any help would be greatly appreciated,

Thanks,

Daniel

[NPowl · Accepted solution]

Hi Daniel,

The reason you're getting the behaviour you're seeing is because you now need to write a 2D array rather than a 1D array. 

When writing for a single TX as a complex double, the input is a 1D array. This is so that you can write a buffer of values into the single channel:

However, when writing for a multi-channel write, you need to change this to a 2D array. This is effectively a 1D array per channel:

If you're just wanting to write the same data through two different channels, you just need to include a "Build Array" function, size this to 2 (for 2 channels) and wire the same value to both inputs of the array function, as in the screenshot above. 

Cheers,

Nick

[dalexander98]

Hi Nick,

Thanks for the guidance, it was very appreciated. The last point you made what exactly what I was looking for, I knew there was probably an array or something I just had to stick in to fix it but wasn't comfortable enough with LabView yet to figure it out.

Thanks again and all the best,
Daniel

[NPowl]

Hi Daniel,

No worries. Have you considered looking at the LabVIEW Core 1 course as an introduction to LabVIEW? It's general-purpose use with DAQ so doesn't explicitly cover the use of the USRP drivers but will help you be more comfortable with the LabVIEW environment in general.

Cheers,

Nick