Advantech ADAM-5511 Manual page 182

com_232_rx_empty()
com_232_tx_empty()
Syntax:
int com_232_rx_empty(void)
int com_232_tx_empty(void)
Description:
Returns the status of the COM2 (RS-232) transmitting and receiving
queues.
Parameter Description
None.
Return value:
Com_232_rx_empty() returns "TRUE" if the receiving queue is empty.
Com_232_tx_empty() returns "TRUE" if the transmitting queue is
empty.
Example:
void main()
{
unsigned char data;
if( com_232_rx_empty()== FALSE)
data =com_232_rx();
}