Serial Port I/O (External Interfaces/API)

Writing and Reading Data

For many serial port applications, there are three important questions that you should consider when writing or reading data:

• Will the read or write function block access to the MATLAB command line?
• Is the data to be transferred binary (numerical) or text?
• Under what conditions will the read or write operation complete?

For write operations, these questions are answered in Writing Data. For read operations, these questions are answered in Reading Data.

Example: Introduction to Writing and Reading Data

Suppose you want to return identification information for a Tektronix TDS 210 two-channel oscilloscope connected to the serial port COM1. This requires writing the *IDN? command to the instrument using the fprintf function, and then reading back the result of that command using the fscanf function.

• s = serial('COM1');
  fopen(s)
  fprintf(s,'*IDN?')
  out = fscanf(s)
  

The resulting identification information is shown below.

• out =
  TEKTRONIX,TDS 210,0,CF:91.1CT FV:v1.16 TDS2CM:CMV:v1.04
  

End the serial port session.

• fclose(s)
  delete(s)
  clear s