This function indicates if the device does or does not exist.
Parameter: device
Type: string
Description: This is the house code and unit code or device code of the
device, such as "A1" or "q17".
Return value: status
Type: long (.NET Integer)
Description: Returns -1
if the device does not exist, otherwise it returns the device reference
ID number of the device. The
reference number can then be used with the GetDeviceByRef
function.