Write and Read ASCII Data over UDP

In this example, write and read ASCII data with a UDP object.

Configure and Connect to the Server

Use an echo server to experiment with the basic functionality of the UDP objects without connecting to an actual device. An echo server is a service that returns to the sender's address and port, the same bytes it receives from the sender.

echoudp("on",4040)

Create a byte-type udpport object. Datagram-type udpport objects do not support communication with ASCII-terminated data.

u = udpport

u = 

  UDPPort with properties:

     IPAddressVersion: "IPV4"
            LocalHost: "0.0.0.0"
            LocalPort: 53816
    NumBytesAvailable: 0

  Show all properties, functions

Write ASCII Data

Use the writeline function to write ASCII data to the server. Write a string to the echo server.

writeline(u,"Request Time","localhost",4040)

The function suspends MATLAB^® execution until all the data is written or a timeout occurs as specified by the Timeout property of the udpport object.

Check the default ASCII terminator.

u.Terminator

ans = 

    "LF"

The writeline function automatically appends the linefeed (LF) terminator to "Request Time" before it is written to the server, indicating the end of the command.

Read ASCII Data

Confirm the success of the write operation by viewing the NumBytesAvailable property.

u.NumBytesAvailable

ans =

    13

Since the udpport object is connected to an echo server, the data you write is returned to the object. Read a string of ASCII data. The readline function reads data until it reaches a terminator, removes the terminator, and returns the data.

data = readline(u)

data = 

    "Request Time"

Clean Up

When you are finished with the UDP object, clear it and turn off the echo server.

clear u
echoudp("off")