Rotenso RAC

Use cases

• Monitor the on/off state and operating mode of Rotenso RAC units across multiple customer sites.
• Adjust the target temperature remotely when a building schedule or season changes.
• Create an alert when the AC unit switches off unexpectedly or enters an unintended mode.
• Log fan speed and operating mode over time to verify comfort and energy performance.
• Set fan speed to Auto or Low during unoccupied hours to reduce energy consumption.

Installation

1. 1Connect the ModbusCloud gateway (MCG or MLP series) to the Rotenso RAC unit using a shielded twisted pair cable on the RS-485 terminals (A, B, GND).
2. 2Set the Modbus slave address on the Rotenso RAC unit according to the manufacturer instructions and note the address for gateway configuration.
3. 3Ensure the communication parameters on the gateway match the RAC defaults: 9600 baud, 8 data bits, 1 stop bit, no parity.
4. 4Import the Rotenso RAC template from the ModbusCloud template library into your project.
5. 5Assign the correct Modbus slave address in the template configuration and verify communication by reading the current on/off state and operating mode.
6. 6If using Modbus TCP/IP, configure the serial-to-TCP bridge on the gateway to forward traffic to the correct COM port and baud rate.

Things to watch for

01

The gateway cannot communicate with the Rotenso RAC unit. What should I check?

Verify that the RS-485 wiring is correct, with A connected to A and B connected to B. Confirm the baud rate is set to 9600 on both the gateway and the AC unit. Also check that the Modbus slave address in the template matches the address configured on the unit.

02

Can I control multiple Rotenso RAC units on the same Modbus bus?

Yes. Each unit must have a unique Modbus slave address. Connect all units in a daisy chain on the RS-485 bus and add a separate template instance for each address in ModbusCloud.

03

Do I need to enable Modbus on the Rotenso RAC before connecting?

Some Rotenso models require Modbus communication to be enabled via the indoor unit settings or a dedicated interface board. Consult the Rotenso installation manual for your specific model to confirm.

04

What is the correct byte order for temperature registers?

The template is preconfigured with the correct byte order and scaling for Rotenso RAC registers. If you see unexpected temperature values, confirm that no byte swap settings have been manually changed on the gateway.

Registers (15)

12 read / 3 write

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