There are two versions of firmware of BT2232 / BT2485 as below

Версия пин-кода

Pin code will be required from Master to pair and connect with BT2232 / BT2485 when it is Slave.

No password version

Pin code will not be required from Master to pair and connect with BT2232 / BT2485 when it is Slave.

Behaviour of the BT2232 / BT2485 as Slave in the No password version

When the BT2232 / BT2485 Slave is paired and locked with a certain Master
It will be only paired with the Master device locked with it

How to lock a BT2232 / BT2485 as Slave with a Master

Reset BT2232 / BT2485
Connect BT2232 to PC via RS232
Connect BT2485 to PC via RS485
Run bluetool utility from PC
Select the accordant COM port & click “Open Port”
Click “Read Parameters” to load the current parameters
Configure “Role” as “S” (means Slave)
Configure “Link” as “1”
Checkmark “Hide”
Click “Write Parameters”
Power on Master device and search this BT2232 / BT2485 Slave
Pair the Master with the BT2232 / BT2485 Slave
BT2232 / BT2485 Slave will be paired only with this Master device once they are paired

How to configure BT2232 / BT2485

Connect BT2232 to PC via RS232
Connect BT2485 to PC via RS485
Run bluetool from PC

How to check if the BT2232 / BT2485 is Pin code version or No password version

Install “Bluetooth V2.1 SPP Setup” from Android mobile

https://play.google.com/store/apps/details?id=com.uconnect.sppsetup&pcampaignid=web_share

Run Bluetooth V2.1 SPP Setup

It will display the connected BT2232 / BT2485 firmware version

If the firmware version ending as ‘D’ means Pin code version

Default pin code is 1234