I want to send a matrix to arduino by matlab but i m unable to open the serial port. using command 'instrfind' i get the status of com3 as close. so fopen() command doesnt execute it gives an error message (Open failed: Port: COM3 ). what to do now?

I want to send a matrix to arduino by matlab but i m unable to open the serial port. using command 'instrfind' i get the status of com3 as close. so fopen() command doesnt execute it gives an error message

Open failed: Port: COM3 is not available. No ports are available. Use INSTRFIND to determine if other instrument objects are connected to the requested device

By instrfind command i am getting Instrument Object Array

   Index:    Type:     Status:   Name:  
   1         serial    open      Serial-COM3
   2         serial    closed    Serial-COM3

 what to do now?

[Bushra Ali]

after clearing the workspace I run the instrfind command again and get these results. Can someone plz specify where I am going wrong.

instrfind

   Serial Port Object : Serial-COM3

   Communication Settings 
      Port:               COM3
      BaudRate:           9600
      Terminator:         'LF'

   Communication State 
      Status:             closed
      RecordStatus:       off

   Read/Write State  
      TransferStatus:     idle
      BytesAvailable:     0
      ValuesReceived:     0
      ValuesSent:         0

Answer 1

[Madhu Govindarajan]

Clearing the workspace is not sufficient to delete existing connections. Try

>> delete(instrfindall)

This should delete existing connections. Then you should be able to create a new connection by typing

>> s1 = serial('COM7') 
>> fopen(s1)

Madhu

PS - Accept the answer if this works. I feel like this will be a frequent flyer and would be great to establish an answer that works for everyone.

[Madhu Govindarajan]

The 'COM7' was an example based on my COM port settings.

[Bushra Ali]

sir is there any way to check the sent data at arduino serial monitor? I have wrote a code:

int a;
void setup() 
{
  Serial.begin(9600);
  pinMode(13, OUTPUT);
}

void loop()
 {
if(Serial.available()>0)
{
a=Serial.read();
Serial.print(a);
if(a==5)
{
  digitalWrite(13,HIGH);
  }
}

}

just to check if data is sent or not. but serial monitor is showing message:

Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

Error opening serial port 'COM3'. (Port busy)

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

[Walter Roberson]

See https://docs.microsoft.com/en-ca/sysinternals/downloads/portmon for one serial port monitor for Windows.

[Madhu Govindarajan]

Here are my thoughts - MATLAB and Serial monitor are fighting for the same resource. So maybe if you close the connection once you are done sending, then hypothetically you should be able to open Serial monitor after that. But all of this is manual and might not work for you, best would be to test it manually and then use the digital pin like you are doing to test if you received the data.

HTH, Madhu