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SensorDAQ real time data acquisition and plotting in matlab

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Hi,

 

I am trying to use Vernier's SensorDAQ to acquire and plot data from a dyanometer in real-time in matlab (see http://www.vernier.com/products/interfaces/sdaq/).

 

I am using the exact same code as I have previously used with an X-series multifunction DAQ (NI USB-6343 ) connected to a pressure sensor. This worked perfectly.

 

Example code: https://uk.mathworks.com/help/daq/examples/acquire-continuous-and-background-data-using-ni-devices.h...

 

However, with the SensorDAQ, it will not plot any data until after the code has finished running. I've tried alternative code and so on, but to no avail. I can only conclude there is a difference in the hardware / on-board software. Any suggestions?

 

Many thanks in advance,

 

Ed

 

 

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Message 1 of 12
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Sorry, I should add the one slight difference in code is you connect to the device using vernier's toolbox:

 

addpath('SensorDAQ')
s = sdaq.createSession;
sdaq.addSensor(s,1,sdaq.Sensors.HandDynamometer);

 

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Hi all,

 

An update from this morning, so I have narrowed it down further:

 

Dev1 is the SensorDAQ, Dev2 is the X series.

 

This code plots both datasets at the end of the script:

 

 

s = daq.createSession('ni');
ch1 = s.addAnalogInputChannel('Dev1','_sensor0_5V','Voltage');
ch2 = s.addAnalogInputChannel('Dev2','ai0','Voltage');
s.Rate = 100;
s.DurationInSeconds = 10;
s.NotifyWhenDataAvailableExceeds = 100;
lh = addlistener(s,'DataAvailable', @(src,event) plot(event.TimeStamps, event.Data));
startBackground(s);
disp('Go')
s.wait();
delete(lh)

 

Whereas, if I comment-out Dev1, this code plots the data from Dev2 in realtime. 

 

 

s = daq.createSession('ni');
% ch1 = s.addAnalogInputChannel('Dev1','_sensor0_5V','Voltage');
ch2 = s.addAnalogInputChannel('Dev2','ai0','Voltage');
s.Rate = 100;
s.DurationInSeconds = 10;
s.NotifyWhenDataAvailableExceeds = 100;
lh = addlistener(s,'DataAvailable', @(src,event) plot(event.TimeStamps, event.Data));
startBackground(s);
disp('Go')
s.wait();
delete(lh)

 

Any idea what in the SensorDAQ might be causing this?

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Message 3 of 12
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Hi Ed,

 

Thanks for getting touch regarding this issue. Can I just confirm, are you using the Vernier toolbox to interface with the sensorDAQ rather than DAQmx? 

 

If so, I believe this issue is best handled by Vernier support as this is their toolbox and is subsequently not supported by National Instruments.

 

EDIT:

Alternatively, if it's this package you're using - https://uk.mathworks.com/matlabcentral/fileexchange/32636-matlab-support-package-for-vernier-sensord...

 

Matlab support may be who you're look for. Please see here for the answer forum from Matlab - https://uk.mathworks.com/matlabcentral/answers/?s_tid=hp_ff_s_answers

 

Best Regards, 

James

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Hi,

Thanks for replying, I have tried both. My first reply above is using the Vernier Toolbox:

 

sdaq.addSensor...

The second reply is using the normal session based DAQmx functions:

s.addAnalogInputChannel...

All the vernier toolbox does is call the standard functions. 

 

Both methods connect to the sensor fine (validated using a single scan e.g.data = s.inputSingleScan).

 

I have tried everything I can think of to get this working! That's why I believe it is something related to the configuration of NI card itself, but that's beyond my technical expertise...

 

Best regards,

Ed

 

 

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Message 5 of 12
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Ah ok, thank you for the clarification. I don't have a particular working familiarity with the usage of the Vernier toolbox however, have you tried creating a session for each of the devices? 

 

Best Regards, 

James Kinch 

Message 6 of 12
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Yes, unfortunately that didn't work.

 

I was initially only using the SensorDAQ so it had it's own session. I only added the other NI card to check my code was correct.

 

(I'm guessing the SensorDAQ is a modified version of NI myDAQ, if anyone is familiar with whether this issue also exists for this card.)

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Message 7 of 12
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Also, looking further into this function pack - https://jp.mathworks.com/hardware-support/nidaqmx.html - you should speak with Matlab support regarding this issue. 

 

Apologies for not being able to offer further support. 

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Message 8 of 12
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Hey Ed,

 

You are correct in saying that the SensorDAQ is essentially a re branded version of a USB DAQ sold by NI (kind of like this - http://sine.ni.com/nips/cds/view/p/lang/en/nid/201986 although this may not be the specific equivalent).

 

From the sounds of things, it's likely a software implementation issue and as such, as I mentioned before it's best supported by Matlab. This said, it may be worth taking a look through the specification document (http://www.vernier.com/files/manuals/sdaq-specifications.pdf) to ensure that you're asking the card to operate within specification.

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Thanks - I took look through the spec, but I'm not really sure what I can change. I've reduced the sampling rate to 10Hz, which it should be more than capable of. Unfortunately, I've had no response from Matlab, so I might have to admit defeat!

 

 

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