Situation #1

Crossover type of RS232 cable should be used for connection between PC and Bluetooth Serial adapter.
Please check if the RS232 cable type is correct or not.

Situation #2

The Bluetooth Serial adapter assigned COM port is occupied (in use) by another Serial host device.

PC system usually reserves COM1 & COM2 for other use.
So the new assigned COM port will start from COM3, COM4,… when more Serial host devices are added to PC.
Please check if the Bluetooth Serial adapter assigned COM port is being used by other device, if so, please change the Bluetooth Serial adapter to other COM port.

Situation #3

Upon clicking “Connect” icon in the BT1 utility to connect with the Bluetooth serial adapter, the Bluetooth Serial adapter button must be pressed and released all within 5~6 seconds so connection can be successful. If not, it will give error message “Connect Fail aa”.