MATLAB REAL-TIME WORKSHOP 7 - TARGET LANGUAGE COMPILER Manual de usuario descargar pdf (Pagina 368)

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8 Serial Port I/O

8-48

Events and Callbacks

You can enhance the power and flexibility of your serial port application by

using events. An event occurs after a condition is met and may result in one or

more callbacks.

While the serial port object is connected to the device, you can use events to

display a message, display data, analyze data, and so on. Callbacks are

controlled through callback properties and callback functions. All event types

have an associated callback property. Callback functions are M-file functions

that you construct to suit your specific application needs.

You execute a callback when a particular event occurs by specifying the name

of the M-file callback function as the value for the associated callback property.

Example: Introduction to Events and Callbacks

This example uses the M-file callback function instrcallback to display a

message to the command line when a bytes-available event occurs. The event

is generated when the terminator is read.

s = serial('COM1');

fopen(s)

s.BytesAvailableFcnMode = 'terminator';

s.BytesAvailableFcn = @instrcallback;

fprintf(s,'*IDN?')

out = fscanf(s);

The resulting display from instrcallback is shown below.

BytesAvailable event occurred at 17:01:29 for the object:

Serial-COM1.

End the serial port session.

fclose(s)

delete(s)

clear s

You can use the type command to display instrcallback at the command line.

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