Problem with fprintf

I am trying to write some data to my serial port using the 'fprintf' command. The command works fine when i run it in my command window but when i try to run the same command in my script file it is unable to write data to the serial port. Please suggest the possible reasons and solutions.

No sir. This question is different. this is my code. It runs well in command window but in my gui it shows error...

global s
s = serial('COM8','BaudRate', 9600,'Parity', 'none','DataBits',8, 'StopBits',1);
s.Terminator = 'CR/LF';
s.BytesAvailableFcnMode = 'terminator';
fopen(s);
pause(0.5);
fprintf(s,'WelkinSat');
pause(0.5);
fprintf('CanSat is Now Ready for Communication--Go WelkinSat \n');
fprintf('Sample data from the main Program... \n');
a=fgetl(s);
disp(a);

[Ryan]

Perhaps sharing a bit of your code will help clarify the issue/causes?

[Oleg Komarov]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Walter Roberson]

I suspect this question is really about sharing variables between functions, which Pradip asked about in a further post http://www.mathworks.com/matlabcentral/answers/40164-calling-variables

[skyimager]

No sir. This question is different. this is my code. It runs well in command window but in my gui it shows error...

global s

s = serial('COM8','BaudRate', 9600,'Parity', 'none','DataBits',8, 'StopBits',1);

s.Terminator = 'CR/LF';

s.BytesAvailableFcnMode = 'terminator';

fopen(s);

pause(0.5);

fprintf(s,'WelkinSat');

pause(0.5);

fprintf('CanSat is Now Ready for Communication--Go WelkinSat \n');

fprintf('Sample data from the main Program... \n');

a=fgetl(s);

disp(a);

[skyimager]

Communication should start after the code "WelkinSat" is written to the device.....but the program is unable to print it....

[Walter Roberson]

What error does it show?

Have you considered the possibility that a pause(0.5) might not be long enough?

[skyimager]

It says....Warning...Terminator Reached before it was called for. I get this error when i try to read from serial port before writing the code WelkinSat to it. That means it is not able to write to the Serial port.

[skyimager]

I first gave the command without pause only but it was nt wrkng. So i thgt pause mite wrk bt no results.

Answer 1

[per isakson]

There are two "different" fprintf. Note "serial" and "object, obj" in the documentation

Doc says:

fprintf (serial)

Write text to device 
Syntax

fprintf(obj,'cmd')
fprintf(obj,'format','cmd')
fprintf(obj,'cmd','mode')
fprintf(obj,'format','cmd','mode')

Description
fprintf(obj,'cmd') writes the string cmd to the device connected to the serial port object, obj. The   default format is %s\n. The write operation is synchronous and blocks the command-line until execution completes.

--- more ---

The object handle shall always be the first argument to fprintf. Doc has this example.

Specify an array of formats and commands:
s = serial('COM1');
fopen(s)
fprintf(s,['ch:%d scale:%d'],[1 20e-3],'sync');

Your statements

fprintf('CanSat is Now Ready for Communication--Go WelkinSat \n');
fprintf('Sample data from the main Program... \n');

should print to the command window according to the documentation.

[per isakson]

I cannot find anything in the documentation that suggest that fgetl(s) can read from a serial port. I think you need to read the documentation more carefully. I added a few lines to my answer above.

[Walter Roberson]

fgetl is implemented for serial.

http://www.mathworks.com/help/techdoc/ref/serial.fgetl.html

[per isakson]

My mistake