Attempt to extract field 'ThermocoupleType' from 'mxArray'.

Question

haryana thomas 2018-6-8

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https://ww2.mathworks.cn/matlabcentral/answers/404786-attempt-to-extract-field-thermocoupletype-from-mxarray

编辑： cristina9 2018-10-12

I'm trying to write code in simulink block editor to take live input data from a thermocouple, through a DAQ system, to display the data on a scope. The thermocouple is a K type thermocouple. If I don't specify the type, I get an error message asking for the thermocouple type. When I specify K type, I get the error 'Attempt to extract field 'ThermocoupleType' from 'mxArray'.'

What should I do?

Code:

function data  = Thermocouple()
coder.extrinsic('daq.createSession','addAnalogInputChannel','startForeground','T')
T = daq.createSession('ni');
ch0 = addAnalogInputChannel(T,'cDAQ9185-1D2BD3AMod2',0,'Thermocouple');
ch0.ThermocoupleType = 'k';
data = zeros(1,1000);
data = startForeground(T);

Thanks in advance!

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Venkata Siva Krishna Madala 2018-6-12

Since "addAnalogInputChannel" is extrinsic, it returns an "mxArray" object, which overrides the data type of "ch0" to be an "mxArray" as well.

In order to solve this error pre-initialize the desired fields / variables, and then assign the value to the field.

Bob Dekraker 2018-6-19

编辑：Bob Dekraker 2018-6-19

在 MATLAB Online 中打开

I'm not exactly sure what to preinitialize it to. Is this what you were thinking?

function data  = Thermocouple()
coder.extrinsic('daq.createSession','addAnalogInputChannel','startForeground','T')
T = daq.createSession('ni');
ch0 = addAnalogInputChannel(T,'cDAQ9185-1D2BD3AMod2',0,'Thermocouple');
ch0.ThermocoupleType = zeros(1,1)
ch0.ThermocoupleType = 'k';
data = zeros(1,1000);
data = startForeground(T);

Thanks

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Answer 1

cristina9 2018-10-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/404786-attempt-to-extract-field-thermocoupletype-from-mxarray#answer_341000

编辑：cristina9 2018-10-12

Same quesiton! I call "timedelaynet" to train a neural network on line in the simulink, and then hope to get the weight value of the neural network. I specify the type of the variable in advance, but it does not work.

coder.extrinsic('net'); net.IW{1,1}=zeros(5,4); %error message:Attempt to extract field 'IW' from 'mxArray' [net,tr]=train(net,inputs,targets,inputStates,layerStates);

What should I do?