Advantech ADAM-5511 Manual page 274

Detect Port Carrier
Detect the carrier signal of specified port
int port_carrier(int portno)
portno
0 : no carrier been detected or bad command or parameter
1 : detect carrier
void main ()
{
port_install(1);
:
:
port_enable_fifo(1);
//if port1 detected carrier, print out the message
if(port_carrier(1));
{
printf("\n port1 detect carrier");
{
}
The specified port number