CDHolding

Retrieves the state of the Carrier Detect (CD or DCD) line.

Read Only at Run-Time.

MSComm32 and Comm32 have identical behavior.

Syntax value = object.CDHolding   object Name of the communications control. value A boolean expression indicating the state of the DCD line.   Example     if object.CDHolding Then       MsgBox ("DCD is On")    Else       MsgBox ("DCD is Off") End If

Remarks:

The DCD line is a 'Modem Control' line. Not usually used when connecting two computers or other 'Terminal' equipment.

When you connect your computer to a modem your modem will change the state of this line to indicate whether a carrier is present.

When the modem is simply powered on and idle this property will be False. Any data you send will only be sent as far as your local modem. For example AT commands etc.

When your modem dials a number and negotiates a connection to a remote modem then this property will become true once the connection is established. Once this property becomes True it means that the modems have finished negotiating and you have a through connection to the remote computer and any data you send will be sent, via the modems, to the remote computer.

If this property unexpectedly goes False during a modem connection then it means that your connection was lost.