Serial connection using PRT3

[BLDmad]

I have an IP150 and connected succesfully, but cannot use more than one connection simultaneously (Insight gold for example).
So I bought a PRT3 to connect via serial /dev/ttyUSB0
Even though all settings seem OK, and I see the RX lighting up when HA tries connection, I get:
025-01-11 13:59:09,937 - INFO - PAI.paradox.connections.serial_connection - Connecting to serial port /dev/ttyUSB0
2025-01-11 13:59:09,943 - INFO - PAI.paradox.connections.serial_connection - Serial port open
2025-01-11 13:59:09,944 - INFO - PAI.paradox.paradox - Connecting to Panel
2025-01-11 13:59:14,962 - ERROR - PAI.paradox.paradox - Timeout while connecting to panel. Is an other connection active?
2025-01-11 13:59:14,962 - ERROR - PAI - Unable to connect to alarm

Can anybody help with this configuration?