Advantech ADAM-5511 Manual page 295

Send Character
Send a character to the THR of the specified port
void port_tx(int portno, char c)
portno
c
None
main()
{
char character
port_installed(1)
:
:
//check whether FIFO empty or not, if empty, send a character
if(port_tx_empty(1);
{
character='a'
port_tx(1, character)
{
}
The specified port number
The character you would like to send