BT232 / BT432IS
When BT232 / BT432IS gives error message as “Connection Fail aa”,
there are 2 situations causing such error as below.
The defined COM port in BT-232 is occupied (in use) by another device.
Usually COM1 & COM2 are reserved for PC’s own use.
When you add more virtual COM port devices to PC, such as USB to RS232 (or else device), system will assign COM port from COM3, COM4,….
For example, assuming you already added to your PC with a USB to RS232 (or else device) which takes use of COM3, and you incidentally define the BT-232 also as COM3, then BT-232 will give error message saying “Connection Fail aa” if COM3 is already in use. So please check if BT-232’s defined COM port is being occupied, and if so, please change to else COM port and try again.
When using BT1 utility (accompanied with the serial to bluetooth adapter),
Upon clicking on “Connect” icon to begin connection, you need to push the serial to bluetooth adapter button and let go within 3 seconds, so it will get connected. If the button is not pushed & let go within 3 seconds upon clicking on “Connect” icon, it will give error message “Connect Fail aa”. So please make sure you push the serial to bluetooth button and let go within 3 seconds upon clicking on “Connect” icon.