Increase Samples/Second for slow Analog Input

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timosmd
Posts: 5
Joined: Mon Oct 14, 2019 3:26 pm

Increase Samples/Second for slow Analog Input

Post by timosmd » Tue Oct 15, 2019 3:14 pm

Hello all,

for a project I need to acquire measurement data from a current (Hall-)sensor via MatLab.

To achieve this target I chose a Stemlab 125-14 as the datasheet for the slow analog input pins states that there is the possibility for 100kS/s.

Yesterday I set up my redpitaya and tried to gather the input voltage with MatLab, altered by a Potentiometer from 0-3.3V.

The problem I encountered is that I was able to achieve a maximum of 20(!) samples per second (with the most minimalistic matlab code possible), which is far away from the sample rate I need to achieve for the project (I would need at least a few thousand kS/s).

My guess is that the query function (volts1 = str2num(query(tcpipObj,'ANALOG:PIN? AIN1'))) in the MatLab code takes too long to read enough samples during a certain time period.

Is there any way to increase the sample rate per second? It seems like you are able to start an acquisition which writes the values to a buffer (which can then be read) by using SCPI commands.
I think this is what I need to do, but I just found commands for the fast RF input but not slow analog inputs (which I need to use).

Sorry for these questions but I already googled/researched a lot and can't find any helpful information regarding this problem.

Hope you can help me with this.

Thanks!
TS

timosmd
Posts: 5
Joined: Mon Oct 14, 2019 3:26 pm

Re: Increase Samples/Second for slow Analog Input

Post by timosmd » Mon Nov 11, 2019 5:31 pm

Update on how I came closer to my goal (in case anyone got the same problem):

I wrote an UDP-Server in C which is running on the RedPitaya and constantly reading the AI and sending the data in chunks to an UDP-socket.

At the same time, my MatLab program is receiving the datagrams from the UDP socket in realtime.

With this workaround I can get around 10-16kS/s which is not enough for my project yet but still much better than 20 samples per second.

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