In order to connect to a focuser you must first select the proper COM port name so that the program knows where to look for the device. To change the selected COM port name, click Settings on the top menu bar and select Change COM Port. All available port names will be displayed to the right as shown in the image below. Click the name of the port you wish to use. If you do not see the desired port name listed, check if another program is currently using the port.
The COM port name can be selected via the ASCOM Driver Setup Dialog form or the TCF-S Focuser Control Program. Since these two programs share the same settings storage file any changes made in one program will be reflected in the other.