Matlab and USB NI 9211A measurement
in [Matlab]
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From: lungu sabin on 25 May 2010 09:05 Hello all, I am student and I start working whit Matlab just 1 month ago but and I need help to synchronizer my acquisition board (NI 9211A). I start whit “ai=analoginput ,channel = addchannel(ai,0)”, I have the results in volt and after the exchange in temperature I don’t find a good values. And I can save just one value, whit getsample. What can I do?
From: us on 26 May 2010 03:53 "lungu sabin" <sabin.lungu(a)yahoo.com> wrote in message <htghu2$cl5$1(a)fred.mathworks.com>... > Hello all, I am student and I start working whit Matlab just 1 month ago but and I need help to synchronizer my acquisition board (NI 9211A). I start whit “ai=analoginput ,channel = addchannel(ai,0)”, I have the results in volt and after the exchange in temperature I don’t find a good values. And I can save just one value, whit getsample. What can I do? > a hint: - carefully read the manual, again - look at the very good demos us
From: Ariane on 1 Jun 2010 10:09 "lungu sabin" <sabin.lungu(a)yahoo.com> wrote in message <htghu2$cl5$1(a)fred.mathworks.com>... > Hello all, I am student and I start working whit Matlab just 1 month ago but and I need help to synchronizer my acquisition board (NI 9211A). I start whit “ai=analoginput ,channel = addchannel(ai,0)”, I have the results in volt and after the exchange in temperature I don’t find a good values. And I can save just one value, whit getsample. What can I do? > I am working on this issue as well. So far I think that the hardware will not support a continuous acquisition, so the matlab demos are not very helpful. You may just have to set it up to get one sample at a time. The reason you are not getting good temperature values is that using the Matlab data acquisition toolbox does not let you reference the internal cold junction sensor (CJC) of the 9211a. You need the voltage value of the CJC in order to extract a true temperature from your thermocouple. However, to access that value, you are going to have to use a C based API to talk to the NI DAQmx driver. Check out these websites, and you should be able to piece together how to get a good temperature reading from your box: http://www.jr-worldwi.de/work/matlab/index.html this one is the most helpful: http://www.mathworks.com/matlabcentral/fileexchange/27609-daqmx-examples http://forums.ni.com/ni/board/message?board.id=250&thread.id=10165&view=by_date_ascending&page=1 good luck
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