Writing a structure to the serial port

[RobWalls]

I need to write a structure to another computer via the serial port, but if i use
fwrite(COM1, structure);
then MATLAB complains that it will only accept a string or numerical argument, not a structure. Is there a different function that i could use to get round this, or do i have to write each member of the structure to the port separately? Thanks for your help,
Rob.