How to get virtual com-port number if DBT_DEVNODES_CHANGED event accrues?
- by Nick Toverovsky
Hi!
Previously I defined com-port number using DBT_DEVICEARRIVAL:
procedure TMainForm.WMDEVICECHANGE(var Msg: TWMDeviceChange);
var
lpdb : PDevBroadcastHdr;
lpdbpr: PDevBroadCastPort;
S: AnsiString;
begin
{????????? ?????????}
lpdb := PDevBroadcastHdr(Msg.dwData);
case Msg.Event of
DBT_DEVICEARRIVAL:
begin {??????????}
if lpdb^.dbch_devicetype = DBT_DEVTYP_PORT {DBT_DEVTYP_DEVICEINTERFACE} then begin
lpdbpr:= PDevBroadCastPort(Msg.dwData);
S := StrPas(PWideChar(@lpdbpr.dbcp_name));
GetSystemController.Init(S);
end;
end;
DBT_DEVICEREMOVECOMPLETE:
begin {????????}
if lpdb^.dbch_devicetype = DBT_DEVTYP_PORT then begin
lpdbpr:= PDevBroadCastPort(Msg.dwData);
S := StrPas(PWideChar(@lpdbpr.dbcp_name));
GetSystemController.ProcessDisconnect(S);
end;
end;
end;
end;
Unfortunately, the hardware part of a device with which I was working changed and now Msg.Event has value BT_DEVNODES_CHANGED.
I've read msdn. It is said that I should use RegisterDeviceNotification to get any additional information.
But, if I got it right, it can't be used for serial ports.
The DBT_DEVICEARRIVAL and
DBT_DEVICEREMOVECOMPLETE events are
automatically broadcast to all
top-level windows for port devices.
Therefore, it is not necessary to call
RegisterDeviceNotification for ports,
and the function fails if the
dbch_devicetype member is
DBT_DEVTYP_PORT.
So, I am confused. How can I define the com-port of a device, if a get DBT_DEVNODES_CHANGED in WMDEVICECHANGE event?
