Connecting mBox to the ATU
The Messana ATU communicates with the mBox controller (mBox, mBox Maxi, mBox5, and mBox10) via Modbus over the RS485. Use a twisted pair cable designed for RS485 communications.
Â
Follow these steps to establish the connection correctly:
- On the mBox side. Connect your cable to the terminals labeled ATU BUS D+/D-. If your cable has a shield, connect it to the terminal labeled SHL only on the mBox side.
- On the ATU main board, connect the cable as follows:
- Connect terminal A to D+
- Connect terminal B to D-
- GRN terminal, leave it unconnected
CAUTION
Do not connect to the terminals labeled (+) and (-):These terminals are dedicated to the unit display and might damage the RS485 port.
Polarity: Ensure correct polarity by maintaining A as positive and B as negative.​
Ground connection: Do not connect anything to the GND terminal on the ATU side. If your cable has a ground wire, only connect it on the mBox side.
Additional Tips for Connection
Daisy chain configuration: If you have more than one unit or other Modbus devices, connect them in a daisy chain configuration. You can connect up to 15 devices.
Using Messana mWire: You can also use the Messana mWire, which is the same wire used for the mSense room sensors. To do this, use the Data Communication twisted pair (White/Green) with aluminum foil shielding and drain wire. Connect the White cable to D+ and A, and the Green cable to D- and B. Connect the Drain Wire to the SHL terminal on the mBox.
Remember to follow these instructions carefully to ensure a successful and safe connection between the mBox and the Messana ATU.