GENERAL AIRSTAGE | CONTROLS REFERENCE

RTPU Controls and anywAiR iO

External Inputs, Modbus RS485, SMT-770 and UTY-RTPU-ANYWIO

Applicable to AIRSTAGE PREMIUM and RAQ single skin rooftop package units using R410A or R454B.

The rooftop unit has an internal Danfoss controller that can operate the machine and provide control inputs and communication to external devices. Where local room control, automatic mode selection or building management integration is required, additional control arrangements may be necessary.

1. Available Control Methods

MethodApplication
Danfoss local controlCommissioning, parameter adjustment and direct unit operation.
External dry contactsRemote on/off, heating/cooling selection and emergency stop.
Modbus RS485Integration with a BMS or compatible external control system.
anywAiR iOOptional programmed controls integration with the Smart Temp SMT-770.

2. External Inputs – Terminal X2

The supplied single skin controls reference identifies the following dry-contact inputs.

X2 TerminalsOpen CircuitClosed Circuit
1 and 2Forced stopRemote start enabled
5 and 6Cooling modeHeating mode
7 and 8Emergency stop activeEmergency stop inactive
  • When remote forced stop is not being used, terminals 1 and 2 should be bridged as specified in the control reference.
  • When emergency stop is not being externally controlled, terminals 7 and 8 should be bridged as specified in the control reference.
  • Do not use the external heat/cool selection input when an in-room controller is also installed, as directed by the control reference.
Important: These are dry-contact control inputs. Do not apply external voltage to these terminals. Any required safety interlocks must remain compliant with the installation design and applicable regulations.

3. Modbus RS485 Integration

Rooftop units can be integrated with building management systems using Modbus RTU over RS485.

ProtocolModbus RTU slave
Default address10
Default baud rate19200
Default serial configuration8N1

A BMS must be appropriately mapped and programmed for the required operating commands, temperature controls, schedules and feedback. A full Modbus points list should be obtained through GENERAL Technical Support where required.

A third-party temperature sensor may be connected to the documented X1-103 and X1-104 inputs for compatible applications. Verify the sensor type and controller programming before connection.

4. Optional UTY-RTPU-ANYWIO Kit

The UTY-RTPU-ANYWIO is an optional control package designed to interface the rooftop unit with an SMT-770 room controller through an anywAiR iO Rubix Compute device.

Kit Components

  • anywAiR iO Rubix Compute controller.
  • 240 V AC to 24 V DC power supply.
  • Smart Temp SMT-770 room controller.

Control Architecture

Danfoss RTPU Controller
Internal machine control
RS485 / Modbus
anywAiR iO Rubix Compute
24 V DC supply
Integrated control and communication arrangement
Smart Temp SMT-770
24 V AC room controller

This is a functional overview only. Follow the UTY-RTPU-ANYWIO installation wiring diagram for the actual wiring connections.

5. Wiring Reference

DeviceConnectionFunction
RTPU X524V / 224 V AC for SMT-770
RTPU X5D1+ / D1-RS485 communication
RTPU X50V / 240VSupply for 24 V DC power supply
SMT-770COMS A / COMS BRS485 + / RS485 -
SMT-77024 / 24C24 V AC active / common
Rubix Compute485-1RS485 connection
Rubix ComputeETH-1Optional Ethernet modem connection

Do not use the Rubix Compute 485-2 connection for this application. Verify that the 24 V AC and 24 V DC power supplies are not interchanged.

6. SMT-770 Configuration

The supplied installation instructions specify:

Modbus address (ad)7
Baud rate (bd)192 (19200 baud)
Parity (pa)0 (None)

To access the installer settings, the UTY-RTPU-ANYWIO guide instructs technicians to hold the O/RIDE button for approximately 15 seconds and follow the installer-menu PIN procedure detailed in the manual.

The supplied guide documents DIP switch 6 as ON when the seven-day timer function is required. The remaining DIP switches must be left in the documented application-specific positions.

7. Rubix Compute and Danfoss Setup

  • Rubix Compute must be powered from the correct 24 V DC supply.
  • Use RS485 port 485-1.
  • Verify RS485 positive, negative and ground connections against the wiring schematic.
  • Confirm that the device switch and status LEDs are in the required state.
  • Configure the Danfoss controller for Modbus address 10 and 19200 baud unless an approved project-specific configuration requires otherwise.
  • The installation manual specifies Danfoss serial format 8N1.

8. Communication Troubleshooting

If the expected communication indicator is absent or the local controller is not communicating:

  1. Verify 24 V AC at the SMT-770.
  2. Verify 24 V DC at Rubix Compute.
  3. Confirm RS485 cable continuity and polarity.
  4. Confirm controller addresses are correct.
  5. Confirm baud rate and parity settings.
  6. Verify Rubix Compute status LEDs and switch settings.
  7. Check for conflicting devices or incorrect BMS configuration.
  8. Confirm machine operation independently before diagnosing complex external control issues.
Supporting Documents
  • R410A and R454B AIRSTAGE_RTPU_Control_Logic V1.pdf
  • Install manual - VERSION 3 - suited to half page.pdf
  • RTPU Commissioning instructions 1.4.pdf

GENERAL AIRSTAGE | Controls reference for qualified technicians.