I wish to have simple GUI communicate serially with microcontroller (PIC) through UART. When press button1 in GUI, LED1 will light up. Press button2, LED2 will light up. I use USB to RS232 converter. In my computer management, under the port category, it shows USB-to-RS232 converter port (COM14). So I use COM14 in my GUI. Unfortunately, it shows an error when I run them. "??? Error using ==> serial.fopen at 72 Port: COM14 is not available. Available ports: COM5, COM12." Why COM14 is not available? But it shows in my computer management. when I use instrfind command, the following information I get:
Instrument Object Array
Index: Type: Status: Name: 1 serial open Serial-COM14 2 serial closed Serial-COM14 3 serial closed Serial-COM14 4 serial closed Serial-COM14
What does it mean? why COM14 is open then closed? Thank you.
Did you turn on the device after you started MATLAB? USB devices have to be fully connected before you start MATLAB or else you will not be able to use them.
If the problem continues, try
and then try to find the port.
There are a few things that you might want to check:
From the output of instrfind, it appears that a serial object for COM14 was created but not cleaned up correctly (it is still available in the memory, which is why instrfind is finding it). Which means as per point 2 above, it will not be available when you try to create another object using the same port.
You might want to check the code to find all the places where you create a serial object and make sure that you are not trying to create multiple objects to the same port. You should use the same object for all your serial communication to that port.
[EDIT: 20110616 08:57 CDT - reformat - WDR]
After collected all the opinions, I successfully change my coding and the program can run. The code is as shown:
function pushbutton3_Callback(hObject, eventdata, handles) delete(instrfind); pause(0.1); s = serial('COM1'); set(s,'BaudRate',9600,'DataBits', 8, 'Parity', 'none','StopBits', 1, 'FlowControl', 'none','Terminator','CR/LF'); fopen(s); fprintf(s,'g'); fclose(s); delete(s); clear s;
Thank you. But it is quite slow, around 3 minutes to react. Does any idea to make it faster? I already change the baud rate but it is still the same. Thank you.