Daikin Setup Bacnet (Service Tool Software)
I find this very handy for checking systems, confirming BACnet settings, and configuring IP addresses on Daikin gateways.
To connect successfully:
Set your laptop IP address to the same subnet as the D-BACS device.
Connect your laptop directly to the D-BACS network or via the same switch.
Open the D-BACS Setup Tool and run device search.
The tool will discover the gateway and allow you to view or modify BACnet/IP settings.


U4 – System Transmission Fault
The fault indicates a communication issue between indoor units. Based on the ability to retrieve the code, I suspect a possible outdoor PCB failure. However, the interconnecting wiring should also be checked to rule out any loose connections or damage.
For reference, I have attached a PDF listing the full set of Daikin fault codes.
Let me know what you find