Is it possible to send different types of data via UDP?

I am trying to send an array of data composed of both double() and uint32() values via UDP as the receiving application requires such a configuration. The size of the data packet should become 40 bytes eventually (4 doubles and 2 ints) However when I inspect the data packets manually the length of the data in the UDP packet drops to 24 bytes when I try to send both types of data.

Does Matlab automatically convert all the data into uint32() data as soon as I try to send both data types?

Thank you all in advance, Bas

Answer 1

[Bas Holten]

I found a (rather sloppy) workaround myself by creating a dummy double precision value to fool the receiving application.

 I1 = uint32(x);
 I2 = uint32(y);

 % Create two 8 hexadecimal byte strings for each of them
 I1_hex = dec2hex(I1,8);
 I2_hex = dec2hex(I2,8);

 % Combine them into a single 16 hexadecimal byte string
 hex_string = strcat(I2_hex,I1_hex); % switched order of the ints to comply with the endianness of the readout

 % Create a dummy value to send via UDP
 dummy = hex2num(hex_string);

This seems to work for the application. As this interface only serves as a testing application it is not terrible that it uses a workaround rather than a solution.

[Dmitriy Makovkin]

Bas, thanks for answering your own question - it has helped me with my own application. Do you know whether it matters if I1 & I2 are declared as uint32? It looks like no matter the type, the dec2hex(I1,8) command will always produce a 16 byte variable. Also, in your example, what is the significance of using 2 variables of the same type? How would the code change if I were interested in sending a uint32, uint16, and a uint8 in one string instead of 2 uint32s?

[Walter Roberson]

dec2hex requires that its input have positive integral value (but not necessarily positive integer data type), and it outputs the hex representation of that integer.