Rockwell Automation Allen-Bradley ControlLogix 1756-MVI Programming Reference Manual page 106

5-18 Serial Port API
Publication 1756-RM004B-EN-P - October 2000
MVIsp_GetDCD
Syntax:
int MVIsp_GetDCD(int comport, int *state);
Parameters:
comport port for which DCD is requested
state pointer to int for desired state
Description:
This function allows the state of the DCD signal to be determined.
comport must be previously opened with MVIsp_Open. The current
state of the DCD signal is copied to the int pointed to by state.
Return Value:
MVI_SUCCESS
MVI_ERR_NOACCESS
MVI_ERR_BADPARAM
Example:
int state;
if (MVIsp_GetDCD(COM1, &state) = = MVI_SUCCESS)
{
if (state = = ON)
printf("DCD is ON\n");
else
printf("DCD is OFF\n");
}
the DCD state was read successfully
comport has not been opened
invalid pointer