I’ve spent quite a while trying to figure out how to REST call the QA403 generator with a user defined signal with just no success. Is there any chance you could provide a small working C# snippet that I could insert and start testing with?
The REST documentation is very sparse. I tried using the TEST REST application but first it crashed when I tried it so I built the application here and then it didn’t crash but it also didn’t output any user signal - it just sent whatever the generator had set prior. When I call it with the documented syntax it outputs nothing and there’s no error result - quite the opposite it returns a SessionId and 0. Trying other syntactical stuff (like adding a Dx) didn’t help.
Take a look around line 353 of the QA402_REST_TEST file linked below. The way it works is that if you generate an array of doubles, and then convert those to base64 and send that to the QA40x app via REST, then the QA403 hardware will “play” the waveform you specify. The doubles are the actual voltage you want. So, an array of doubles with sin that peaks at +/- 1.41, then you’ll measure 1Vrms on the output
I absolutely tried the test application already and it didn’t work for me. Could you please ensure it does what you think? When I tried these exact lines of code it produced no output afaik.
To test this over the weekend, I downloaded the Rest Test app from github and compiled it and ran it here. When I ran it I checked the time and frequency results from the acquired data and they had nothing in them other than noise. Am I just totally missing something?
By the way, I’m not sure I know what left and right are in the acquisition call. Can you send different output to each channel?
Hi @MarkZ, make sure the size of the buffers you are preparing match the size of the FFT you have selected, and that they are both powers of two. I just cloned RESTTEST, ran it, pushed the POST /Acquisition w/User Data button while the main QA40x app was set to 32K fft. Nothing came out. Then, I set the main app to 8K fft, pushed the same button again, and the clipped waveform appeared on my scope.
I updated the REST localhost webpage to indicate the buffer size needs to match, and also pushed up a new version of the QA402_REST_TEST with an explicit call to set the buffer in the UserSubmittedStimulus().
Can you see if this fixes your issue? Thanks very much for reporting!
Yes, that’s correct. if you write your own code, you can independently control the left and right channels. You can send a square to the left channel, and a triangle the right channel, for example.
