Matlab does not recognize serial port

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Daniel Ramos 2018-5-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/401974-matlab-does-not-recognize-serial-port

编辑： vibhorag 2019-6-28

Right now I'm trying to use Matlab to read in serial data through an FTDI interface with an RS422 on a laptop running Centos 6. The data is passed through every 25 seconds or so. I already have code that runs with another computer, and I know the laptop itself can receive the data (have confirmed this using cutecom). The current issue is that I cannot access the serial port in Matlab.

So far I have tried to create a symbolic link from /dev/ttyUSB0 (what the laptop recognizes as the port going to the RS422) to /dev/ttyS101 as described here. I also tried adding a java.opts file to specify which serial ports Matlab should be looking as described in the answer here.

I've verified permissions: used ls -l /dev/ttyUSB0 and got the following result:

crw-rw---- 1 root dialout 188

And I made sure I was in the dialout group.

Any suggestions on what to try next?

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Ameer Hamza 2018-5-22

How are you trying to access the serial port and what is the error given by MATLAB?

Daniel Ramos 2018-5-22

在 MATLAB Online 中打开

Through a USB-to-RS422 cable. Running the following code:

s = serial('/dev/ttyUSB0')
fopen(s)

I get:

Error using serial/fopen (line 72)
Open failed: Port: /dev/ttyUSB0 is not available. No ports available.
Use INSTRFIND to determine if other instrument objects are connected to the requested device.

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Answer 1

Ameer Hamza 2018-5-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/401974-matlab-does-not-recognize-serial-port#answer_321410

在 MATLAB Online 中打开

Make sure that no other program is accessing the serial port. Close all other programs which might be accessing the serial port and then try again. Also in MATLAB check the output of

instrfind

If it is non-empty then run the following lines before trying again