TMReadDefaultPort Overview Group

The TMReadDefaultPort API call reads the default 1-Wire port number and type from the system registry. The port number and port type are both integers that describe on which port the 1-Wire network is connected and through which port adapter type.

The port numbers can be an integer from 0 to 16. Most valid port numbers on PCs are 1, 2, or 3. The following is a list of port adapter types:

1           Older DS9097E-type serial port adapters
2           Parallel port adapters
5           Standard DS90907U-type serial port adapters
6           USB port adapters

short far pascal TMReadDefaultPort(

short far *portnum,     // port number of port (serial, parallel, or usb)
short far *porttype,    // the type of port adapter used.

For a description of the above types, see the TMEX Type Descriptions.



Specifies the port number of the specific port (serial, parallel, or usb) where the 1-Wire network is located. Most port numbers on PCs are 1, 2 or 3.


Specifies the port adapter type. There are a variety of PC-to-1-Wire adapters available. For a short list, see above. For a more in-depth list of adapters and their respective port type numbers, please see the TMEX API Overview. Currently used numbers are: 1, 2, 5, and 6.

Return Value

1 => defaults were returned

-2 => defaults not found

Code Example

See Also