ASYNC GETMODEMOUTPUT

Returns the modem control output signals.

Category

IOCTL_ASYNC (01h)

Function

ASYNC_GETMODEMOUTPUT (66h)

Parameter Packet Format

None. Packet pointer must be NULL.

Data Packet Format

┌──────────────────────────────────────────────────────┐
│Field                          Length     C Datatype  │
├──────────────────────────────────────────────────────┤
│Modem Control Output Status    BYTE       UCHAR       │
└──────────────────────────────────────────────────────┘

Modem Control Output Status

If a bit has a value of 1, the condition is on. If a bit has a value of 0, the condition is off.

Bit 0

:Data Terminal Ready (DTR)

Bit 1

:Request To Send (RTS)

Bits 2-7

::Undefined

Returns

If the call is made with an invalid Parameter Packet value, a general failure error is reported and valid information is not returned in the Data Packet.

Remarks

If a general failure error is not returned, the physical device driver returns the current modem control output signals of the COM device.