Serial Read Error

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skyimager
skyimager 2012-5-30
评论： Muhammad Munam Naseer 2016-8-27
I am trying to read data from serial port. The port being used is COM1. I am getting the following error :
??? Error using ==> serial.fopen at 72
Port: COM1 is not available. Available ports: COM8, COM17, COM19.
Use INSTRFIND to determine if other instrument objects are connected to the requested device.
Please suggest possible reasons.
[Merged information from duplicate question]
I am using Windows 7 32 bit. Matlab verison is 2011a.
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Thisara
Thisara 2016-8-13
编辑：Thisara 2016-8-13
use this code on first line of script
delete(instrfindall);
Muhammad Munam Naseer
Muhammad Munam Naseer 2016-8-27
@ Thisara Thanx it worked

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采纳的回答

Walter Roberson
Walter Roberson 2012-5-30
1) The COM port name you are trying to use perhaps does not correspond to a valid COM port
2) The COM port might already be in use in that MATLAB session. Quit and restart MATLAB and try again.
3) COM1 might already be allocated for the mouse (serial mouse, older systems)
4) COM1 might already be allocated for use as a modem (a problem seen more often on laptops)
5) You are using a virtual COM port over USB and you did not have it connected at the time you started MATLAB
6) You are using a virtual COM port over USB and you disconnected it at least once after you started MATLAB
7) You are using an older system in which COM1 shares the interrupt line with COM5 and COM5 is already in use
8) Installation problems
9) User Access Controls set up on COM1 do not allow you to use it
10) It is MS Windows; it doesn't need any good reason to act oddly.
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skyimager
skyimager 2012-5-31
I checked in my device manager. COM1 is the port that the arduino is connected to. Also using instrfind command i confirmed that COM1 is available.
I read somewhere that we have to define the ports we propose to use in our program in the matlab library. But I don't know how to define that.
Walter Roberson
Walter Roberson 2012-5-31
I _suspect_ that you might be referring to defining the port when using Linux, as Linux's serial port names are a lot more complex than "COM1".
Anyhow, if you had the program crash (easy enough to have happen during development) then the serial port might not have gotten closed properly. Try fclose('all')

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Thisara
Thisara 2016-8-13
use this code on first line of script
delete(instrfindall);

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