Advantech ADAM-5511 Manual page 279

Read Modem Status (MSR)
Read from specified port modem status register
int port_get_modem_status(int portno)
portno
0x00XX
0xFF00
void main ()
{
int MSR_Value;
port_install(1);
:
:
port_enable_fifo(1);
//get MSR value
MSR_Value=port_get_modem_status(1);
}
Register Description
Name
MSR Modem
Status
Register
The specified port number
:
:
Bit7 Bit6 Bit5
DCD RI DSR
modem status
bad command or parameter
Bit4 Bit3 Bit2
CTS Delta Trailing
DCD RI edge
Bit1 Bit0
Delta Delta
DSR CTS