If you are experiencing issues connecting your Android phone to the ACDP2 host using a USB cable and the USB prompt pop-up window does not appear, follow the steps below to resolve the issue.
Step-by-Step Solution
1. Connect the ACDP2 Host to Your Android Phone
Connect the ACDP2 host to your phone using a compatible Android USB cable.
Open the ACDP software on your device.
2. Check for the USB Prompt Pop-Up
If the USB prompt pop-up window does not appear, the ACDP host may not be recognized by your phone.
3. Enable OTG Connection
Go to your phone’s Settings.
In the search bar, type "OTG" and select the OTG connection.
You will see a message: "Automatically turns off if not used for 10 minutes."
Turn on the OTG switch.
4. Return to ACDP Software
After enabling OTG, switch back to the ACDP software.
The USB prompt pop-up window should now appear.
5. Confirm the Connection
Click "Close" on the pop-up window.
Then click "OK" to finalize the connection.
Once these steps are completed, your Android phone should successfully connect to the ACDP2 host.
Article source: http://blog.obd2shop.co.uk/fix-android-phone-usb-connection-failure-with-acdp2/