Issues with Red Pitaya DAQ board LabVIEW development

[AMixon]

Hi,

I am using a Red Pitaya 125.14 DAQ board for controlling a 2D scanning Multiphoton Microscope (MPM) system. From the board, I need to generate two signals, viz., a triangular waveform with 100 Hz and 1 Vpp (the maximum the board can generate from its fast output channels) and a sawtooth up waveform with 1 Hz and 1 Vpp. These two signals control the X- and Y-galvo mirrors installed in the MPM system. There are Analog Output pins with which corresponding voltages will get generated. After running the scan, the detection system being a PMT, the pixel intensity values are fed to Analog Input pins of the Red Pitaya DAQ board which will then have a corresponding voltage to convert to.

The issue is when I run the subVI, a 2016 version of LabVIEW VI is attached to this query, that generates the waveform, I can see exactly what is to be expected on the oscilloscope. For example, generating a triangular wave with 100 Hz and 1 Vpp, the oscilloscope shows it the way it is, as shown in the attached snapshot. But the waveform array just gives out a noise-like output as shown in the attached subVI front panel snapshot. In the subVI while loop, and outside, I have introduced the waveform chart and graphs at different places such that I can get a better idea of what might be happening.

Can anyone please guide me as to why this might be happening? What are the remedial steps? Has anyone worked with the Red Pitaya board found it any easier to work with it on LabVIEW for complicated tasks? The response to the queries related to LabVIEW from Red Pitaya hasn't been that helpful. Also, I haven't developed programs with LabVIEW that often, therefore, the whole process becomes furthermore on the slower side. Particularly for Red Pitaya software development, I have found it easier to work with Python. With LabVIEW for Red Pitaya development, I have faced challenges for even simpler tasks because quite a few necessary blocks aren't provided by them.

Also can you please show me the correct way to stop the signal generated from the Red Pitaya DAQ board upon pressing a stop button in this VI? Other than the non-functional way of doing so in the subVI attached, I have tried other ways too but it hasn't worked.

Any solutions/pointers/suggestions regarding these will be greatly helpful. Thank you!

[VA.KI]

Hello AMixon,

I think this behavior was expected.

I noticed that you are writing and reading from the same channel at the same time.

So what you expect?

When you read from the channel you will get values applied to it and in your case there is nothing driving that input.

It looks like that you are trying to drive (to make it output) the channel and read (make it input) it at the same time. You don't have loop-back there.

So what is the task?

[pranavrs]

I am facing the exact same issue as posted by AMixon

On the oscilloscope I can see the correct shape of the waveform generated. However, when I try to read the generated waveform it using Red Pitaya's fast input channels, I am unable to see the waveform (only random noise is observed). 

I am using the generate and read waveform vi provided in the LabView examples for red pitaya (as available in the library). I would like to know if someone has found a solution for this issue.