Readwrite command in Data Acquisition toolbox returns "Unexpected exception in plug-in: 'Input data can only contain ASCII characters.'" Even with no input plugged in.

John Sterling

2021 12 6

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I am trying to write an mfile to take an arbitrary signal vector, output it, and read the response from an accelerometer. On the way to this, I have successfully used the read command on the accel data from an accelerometer, and in my main code, the shaker triggers from the output signal. I have used this DAQ for a while with no problems in LABVIEW. But, once I invoke the readwrite command, nothing works. I kept getting the following error, with a square symbol as the only explanation for the error. Edit: I actually had to edit out the symbols because it broke the rest of the post.

>> sigreader

Error using sigreader (line 15)

So I copied the code directly from https://www.mathworks.com/help/daq/acquire-data-and-generate-signals-at-the-same-time.html

dq = daq("ni");
addinput(dq, "Dev1", "ai0", "Voltage");
addoutput(dq, "Dev1", "ao1", "Voltage")  %%Updated this for my personal DAQ
output = cos(linspace(0,2*pi,1000)');
plot(output);
title("Output Data");
data1 = readwrite(dq, output);
plot(data1.Time, data1.Variables);

This generates the following error:

>> rwtest

Error using rwtest (line 10)

Unexpected exception in plug-in: 'Input data can only contain ASCII characters.'

At this point I have disconnected all of the sensors so the daq block is just empty. To reiterate, input works just fine using the read command, and the output will trigger using the readwrite command. I am at a loss and any ideas would be appreciated.

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策符洪 2022-3-1

I had a similar error, when I am trying ros command(ros2 topic list). I changed the character encoding to US-ASCII(slCharacterEncoding), but error still happened.