Change Device Assigned to Outbound COM Port

With the Microsoft Bluetooth stack a single outbound virtual COM port is supported, to set this up you have to bond with the device. If you want to switch between several devices at different times this is awkward. You can however alter the registry settings between connections to switch devices.

1. Setup an Outbound COM port for the first device

2. Bond with the other device(s) you wish to use

3. Make a note of the bluetooth IDs of these bonded devices – see the subkeys of [HKEY_LOCAL_MACHINESOFTWAREMicrosoftBluetoothDevice] for details

4. Before switching devices ensure you do not have the outbound virtual COM port opened (often COM 5 but check on your device).

5. Replace the value of “OBBDaddr” in the key [HKEY_LOCAL_MACHINESOFTWAREMicrosoftBluetoothSerialPort] with the bluetooth address of your required device.

6. Open the COM port – now connects to the device specified in the above registry key.

By Peter Freeman Foot

Microsoft Windows Development MVP