SIEMENS RS485 Flush Mounted Room Thermostat User Manual

SIEMENS RS485 Flush Mounted Room Thermostat

Specifications:

• Product: Flush-mounted room thermostat with RS485 Modbus communications
• Models: RDF660MB/MM, RDF660MB
• Compatible with: 2-pipe, 2-pipe with electric heater, and 4-pipe fan coil units
• Mounting: Suitable for round and square conduit boxes with 60 mm fixing centers

Product Usage Instructions:

Applications:
The room thermostat is designed for room temperature control in individual rooms and zones using various fan coil units.

• 2-pipe fan coil units
• 2-pipe fan coil units with electric heater
• 4-pipe fan coil units

Controls:
The thermostat can control:

• ECM fan
• On/off valve actuators
• Compressor with electric heater
• Other components based on the system configuration

Commissioning:
The thermostat comes with preset applications that can be activated during commissioning using DIP switches, HMI, or Modbus commissioning tools.

Functions:

• Maintain room temperature using built-in or external temperature sensors
• Changeover between heating and cooling modes (manual or automatic)
• Purge function in 2-pipe systems
• Cleaning filter reminder
• Floor heating temperature limit
• Restore factory settings

Communication:
The thermostat supports RS485 Modbus communication for integration with compatible devices.

Mounting:
The thermostat can be mounted on both round and square conduit boxes with 60 mm fixing centers.

FAQ:

• How do I change the thermostat settings?
  You can change the settings during commissioning using DIP switches, HMI, or Modbus tools.

• Can this thermostat work with both heating and cooling systems?
  Yes, the thermostat is suitable for systems that require both heating and cooling functionalities.

• What is the communication protocol supported by this thermostat?
  The thermostat supports RS485 Modbus communication for seamless integration with Modbus compatible devices.

Flush-mounted room thermostat with RS485 Modbus communications
RDF660MB/MM, RDF660MB

For 2-pipe, 2-pipe with electric heater and 4-pipe fan coil units

• AC 230 V operating voltage
• Large, backlit display
• On/off or 3-position control outputs
• Automatic or manual fan speed control
• ECM fan DC 0…10 V output
• Operating modes: Comfort, Economy and Protection
• Control depending on the room or the return air temperature
• Automatic or manual heating/cooling changeover
• Minimum and maximum limitation of room temperature setpoint
• 2 inputs for external or changeover sensor, keycard or window contact
• Commissioning and control parameters via local HMI or RS485 Modbus
• RS485 communicative interface in Modbus RTU slave mode
• User and parameter settings can be retained or restored with power loss to previous mode, Comfort mode or Protection mode
• Mounting on both round and square conduit boxes, 60 mm fixing centers

Use

Applications
Room temperature control (heating or cooling) in individual rooms and zones by means of:

• 2-pipe fan coil units
• 2-pipe fan coil units with electric heater
• 4-pipe fan coil units

The room thermostat controls:

• One ECM fan
• One or two on/off valve actuators
• One on/off valve actuator and one 1-stage electric heater
• One 3-position valve actuator
• One 1-stage compressor with electric heater

Used in systems with:

• Heating or cooling
• Automatic heating/cooling changeover
• Manual heating/cooling changeover
• Heating and cooling (e.g. 4-pipe system)

The room thermostat is delivered with a fixed set of applications.
The relevant application is selected and activated during commissioning using one of the following tools:

• Local DIP switch and HMI
• Modbus commissioning tools

Functions

• Maintain room temperature via built-in temperature sensor or external room temperature/return air temperature sensor
• Changeover between heating and cooling mode (automatic changeover via local sensor/bus or manual changeover via buttons)
• Select application via DIP switches or commissioning tools
• Select operating mode via operating mode button on the thermostat
• ECM fan control (automatic or manual)
• Display current room temperature or setpoint in °C and/or °F
• Minimum and maximum limitation of room temperature setpoint
• Key lock (automatic, manual or via bus)
• B1 input freely selectable for (RDF660MB/MM only):
  • External room temperature sensor or return air temperature sensor
  • Automatic heating/cooling changeover sensor
• S1 input freely selectable for (RDF660MB/MM only):
  • Window contact
  • Presence detector
  • Hotel keycard
• 2 multifunctional inputs (X1 and X2), freely selectable for (RDF660MB only):
  • External room temperature sensor or return air temperature sensor (AI)
  • Automatic heating/cooling changeover sensor (AI)
  • Window contact (DI)
  • Dew point sensor (DI)
  • Electric heater enabled (DI)
  • Fault input (DI)
  • Monitor input (DI)
  • Monitor input (AI)
  • Automatic heating/cooling changeover sensor (DI)
  • Presence detector (DI)
  • Hotel keycard (DI)
• Advanced fan control function, e.g. fan kick, fan start, selectable fan operation (enable, disable or depending on heating or cooling mode)
• Purge function together with 2-port valve in a 2-pipe changeover system
• Reminder to clean filters
• Floor heating temperature limit
• Reload factory settings for commissioning and control parameters
• User and parameter settings can be retained with power loss and operating mode can be returned to previous operating mode, Comfort mode or Protection mode (depends on P27)
• RS 485 Modbus (terminals +, – and REF) for communication with Modbus compatible devices
• Display on a secondary line: room temperature, outdoor temperature or time of day via Modbus
• Mounting on both round and square conduit boxes, 60 mm fixing centers

Type summary

Product no.| Stock no.| Operating voltage| Control outputs| Fan types| Backlit LCD| Input| Suitable conduit box| Color
---|---|---|---|---|---|---|---|---
On/Off| 3-pos| DC 0…10 V| 3-speed| DC 0…10 V
RDF660MB/ MM| S55770- T433| AC 230 V| ✓| ✓| –| –| ✓| ✓| Basic B1, S1| Square or round| White
RDF660MB| S55770- T439| AC 230 V| ✓| ✓| –| –| ✓| ✓| Basic X1, X2| Square or round| White

Ordering
When ordering, specify both product number/stock number and name: e.g. RDF660MB/MM / S55770-T433 Modbus room thermostat
Order valve actuators and accessories separately

Accessories

Plastic mounting spacer for flush-mounted thermostats to increase the headroom in the conduit box by 10 mm| ****| ARG70.3| N3009

Note: Order accessories separately.

Equipment combinations

On/Off actuators

3-position actuators

*) The documents can be downloaded from http://siemens.com/bt/download.
For the maximum number of actuators in parallel, refer to information in the data sheets of the selected actuators and to this list, depending on which value is lower:

• Parallel operation of max 6 SS… actuators (3-pos) is possible.
• Parallel operation of max 10 On / Off actuators is possible.
• Parallel operation of SQS35 is not possible.

Mechanical design

The thermostats consist of 2 parts:

• Front panel with electronics, operating elements and built-in room temperature sensor.
• Mounting base with power electronics.

The rear of the mounting base contains the screw terminals. The base fits on a square conduit box with 60 mm fixing centers. Slide the front panel in the mounting base and snap on.

Operation and settings

1. Operating mode selector
2. Change fan operation
3. Adjust setpoints and control parameters

Display

Product documentation

Related documents such as environmental declarations, CE declarations, etc., can also be downloaded at the following Internet address: http://siemens.com/bt/download

Notes

  CAUTION

**| National safety regulations**

Failure to comply with national safety regulations may result in personal injury and property damage.

• Observe national provisions and comply with the appropriate safety regulations.

Engineering

• Device address The device address is assigned to “1” (factory setting). If necessary, engineer/installer can change the address value using the parameter P81.
• Baud rate  The Baud rate is selectable. Four options, 9600 bps, 19200 bps 38400 bps and 57600 bps, are available for the Modbus network (19200 bps is default).
• Parity Parity can be set to none, odd or even (even is default).

Mounting and installation

Mounting

• Mount the room thermostat on a recessed square conduit box with 60 mm fixing centers.
• Do not mount on a wall in niches or bookshelves, behind curtains, above or near heat sources, or exposed to direct solar radiation.
• Mount about 1.5 m above the floor.
• Mount the room thermostat in a clean, dry indoor place without direct airflow from a heating / cooling device, and not exposed to dripping or splash water.
• In case of limited space in the conduit box, use mounting bracket ARG70.3 to increase the headroom by 10 mm.

  WARNING

| Device damage

Carefully read all wiring diagrams prior to installation to avoid damage to the device caused by incorrect wiring of high or low voltages.

Wiring

• See Mounting Instructions A6V12060783 enclosed with the thermostat.
• Comply with local regulations to wire, protect and earth the thermostat.
• The device has no internal fuse for supply lines to fan and actuators. To avoid risk of fire and injury due to short-circuits, the AC 230 V mains supply line must have a circuit breaker with a rated current of no more than 10 A.
• Properly size the cables to the thermostat, fan and valve actuators for AC 230 V mains voltage.
• Use only valve actuators rated for AC 230 V.
• Adapt the wiring cross section for power supply (L, N), and 230 V outputs (Yx-N) to the preceding overload protection elements (max 10 A) under all circumstances. Comply with local regulations under all circumstances.
• Cables of SELV inputs S1 (X2)-M / B1 (X1)-M: use cables with min 230 V insulation, as the conduit box carries AC 230 V mains voltage.
• Inputs S1 (X2)-M / B1 (X1)-M: several switches (e.g. summer/winter switch) may be connected in parallel. Consider overall maximum contact sensing current for switch rating.
• Selectable relay function: Follow the instructions in Basic documentation A6V12114068 to connect external equipment to the relay outputs.
• Isolate the cables of Modbus communication input A+, B- and REF for 230 V.
• Disconnect thermostat from power supply before removing from the mounting plate.
• The device does not support hot-plug.

Operating mode
In Protection mode, press any button to activate the screen, then press the mode button to change to another operating mode.

Commissioning

Applications

• The room thermostat is delivered with a fixed set of applications.

• Select and activate the relevant application during commissioning using one of the following tools:

  • Local DIP switch and HMI
  • Modbus commissioning tools

• Set the DIP switches before snapping the front panel onto the mounting plate, if you want to select an application via DIP switches.

• All DIP switches need to be set to “OFF” (“remote configuration”), if you want to select an application via commissioning tools.

• After power is applied, the thermostat resets and all LCD segments light up, indicating that resetting was correct. After the reset, which takes about 3 seconds, the thermostat is ready for commissioning by qualified HVAC staff.

• Display “NONE”  If “NONE” is displayed on the LCD, the DIP switches are set to OFF-OFF-OFF for remote configuration, but the application has not yet been assigned to the device.

• The application can be set using commissioning tools via RS485 Modbus.
  Note

• When the application is changed, the thermostat reloads the factory settings for all control parameters, except baud rate (P82), parity (P83) and zone addresses (P81)!

• Control  parameters  The thermostat’s control parameters can be set to ensure optimum performance of the entire system.
  The parameters can be adjusted via

  • Local HMI
  • Modbus commissioning tools

• Control sequence
  The control sequence may need to be set via parameter P01 depending on the application. The factory setting for the 2-pipe application is “Cooling only”; and “Heating and cooling” for the 4-pipe application.

• Compressor-based application
  When the thermostat is used with a compressor, adjust the minimum output On- time (P48) and Off-time (P49) for Y1/Y2 to avoid damaging the compressor or shortening its life due to frequent switching.

• Calibrate sensor  Recalibrate the temperature sensor if the room temperature displayed on the thermostat does not match the room temperature measured (after minimum 1 hour of operation). To do this, change P05.

• Setpoint and range limitation  We recommend reviewing the setpoints and setpoint ranges (P08…P12) and changing them as needed to achieve maximum comfort and save energy.

Disposal This symbol or any other national label indicate that the product, its packaging, and, where applicable, any batteries may not be disposed of as domestic waste. Delete all personal data and dispose of the item(s) at separate collection and recycling facilities in accordance with local and national legislation.
For additional details, refer to www.siemens.com/bt/disposal.

Open Source Software (OSS)
All open source software components used within the product (including their copyright holders and the license conditions) can be found from the website
https://www.siemens.com/download?A6V11893104.

Warranty

Technical data on specific applications are valid only together with Siemens products listed under “Equipment combinations”. Siemens rejects any and all warranties in the event that third-party products are used.

Technical data

Power supply

Operating voltage| AC 230 V +10/-15 %
Frequency| 50/60 Hz
Power consumption| 9 VA
**No internal fuse!
External preliminary protection with max. C 10 A circuit breaker required in all cases.
Outputs**

DC fan control DC 0…10 V; Y50| SELV DC 0…10 V, max. 5 mA
Control output

Y1-N / Y2-N (N.O.)

Rating

| **** AC 230 V

Max. 5(2) A

Multifunctional inputs

S1 (X2)-M/B1 (X1)-M
Temperature sensor input
Type| NTC (3 kΩ at 25 °C)
Temperature range| 0…49 °C
Cable length| Max. 80 m
Digital input
Operating action| Selectable (NO/NC)
Contact sensing| SELV DC 0…3.3 V, max. 1 mA
Parallel connection of several thermostats for one switch| Max. 20 thermostats per switch
Insulation against mains voltage (SELV)| III (4 kV), reinforced insulation| Modbus

Interface type| RS485 Modbus RTU

Wire (ref.): 16 AWG, 1 pair, shielded serial line with 1.5 mm2 and length < 1200 m

Bus current| Max. 50 mA
Bus topology: See Modbus manual (Modbus over serial line specification and implementation guide from http://www.modbus.org)
Operational data

Switching differential, adjustable
Heating| (P30)| 2 K (0.5…6 K)
Cooling| (P31)| 1 K (0.5…6 K)
Setpoint setting and setpoint range
Comfort| (P08)| 21 °C (5…40 °C)
Economy| (P11-P12)| 15 °C/30 °C (OFF, 5…40 °C)
Protection| (P65-P66)| 8 °C/OFF (OFF, 5…40 °C)
Multifunctional input B1 (RDF660MB/MM only)| Selectable (0, 1, 2, 9)
Input default value| (P38)| 9: H/C changeover (DI)
Multifunctional input S1 (RDF660MB/MM only)| Selectable (0, 3, 10, 11)
Input default value| (P40)| 3: Window contact (DI)
Multifunctional inputs X1/X2 (RDF660MB only)| Selectable (0…11)
Input X1| 3 (P38) Window contact (DI)
Input X2| 1 (P40) External temperature sensor
Built-in room temperature sensor
Measuring range| 0…49 °C
Accuracy at 25 °C| < ±0.5 K
Temperature calibration range| ±5 K
Settings and display resolution
Setpoint| 0.5 °C
Current temperature value displayed| 0.5 °C
Environmental conditions

Storage| IEC 60721-3-1
Climatic conditions| Class 1K3
Transport| IEC 60721-3-2
Climatic conditions| Class 2K3
Operation| IEC 60721-3-3
Climatic conditions| Class 3K5 1)
Standards and directives

EU conformity (CE)| A5W00156993A
RCM conformity| A5W00156996A
Safety class| II as per EN 60730-1
Pollution class| Class 2
Degree of protection of housing| IP30 as per EN 60529
Housing flammability class according to UL94| V-0
Environmental compatibility| The product environmental declaration (A5W00139322A *) contains data on environmentally compatible product design and assessments (RoHS compliance, materials composition, packaging, environmental benefit, disposal).
General

Connection terminals| Solid wires or prepared stranded wires

1 x 0.4…1.5 mm2

Housing front color| RAL 9003 white
Weight without/with packaging| 148 g/241 g

The documents can be downloaded from http://siemens.com/bt/download.

1. No condensation is allowed.

Diagrams

Connection terminals

output for compressor or output for electric heater

B1, S1 (RDF660MB/MM

only)

| Multifunctional input for temperature sensor (e.g. QAH11.1) or potential- free switch

Factory setting:

B1 = H/C changeover (DI) S1 = Window contact

X1, X2 (RDF660MB

only)

| Multifunctional input for temperature sensor (e.g. QAH11.1) or potential- free switch

Factory setting:

X1 = Window contact

X2 = External temperature sensor

M| Measuring neutral for sensor and switch
REF| RS485 signal / common ground (differential common)
A +| RS485 Modbus connection
B –| RS485 Modbus connection

Connection diagrams

S2       Switch (keycard, window contact, presence detector, etc.)
B2        Temperature sensor (return air temperature, external room temperature, changeover sensor, etc.)
+         RS485 Modbus connection| –          RS485 Modbus connection
REF     RS485 signal/common ground (differential common)
M1       DC 0…10 V fan| E1       Electric heater (RDF660MB only)

Application examples
The thermostats support the following applications, that can be configured using the DIP switches inside the front panel of the unit or a Modbus commissioning tool.
Remote  configuration
All DIP switches need to be set to OFF (factory setting) to select an application via commissioning tool.

Applications for fan coil systems

V1     Heating or heating/cooling valve actuator| B1    Return air temperature sensor or external room temperature sensor (optional)
---|---
V2     Cooling valve actuator| B2    Changeover sensor (optional)
E1     Electric heater (RDF660MB only)| M1 ECM fan

V1     Heating or heating/cooling valve actuator| B1    Return air temperature sensor or external room temperature sensor (optional)
---|---
V2     Cooling valve actuator| B2    Changeover sensor (optional)
E1     Electric heater (RDF660MB only)| D3 Dewpoint sensor

Application for heat pump systems

N1 Thermostat

Terminal Y1: Heating (H&C) or Heating/Cooling Terminal Y2: Cooling (H&C)

| B1 Return air temperature sensor or external room temperature sensor (optional)
---|---
E1 Electric heaters (RDF660MB only)| D3 Dewpoint sensor

Dimensions

© Siemens Switzerland Ltd, 2021
Technical specifications and availability subject to change without notice.

• Issued by
• Siemens Switzerland Ltd
• Smart Infrastructure
• Global Headquarters
• Theilerstrasse 1a
• CH-6300 Zug
• +41 58 724 2424
• www.siemens.com/buildingtechnologies
• Document ID  A6V12005486_en–_d
• Edition  2022-11-14

References

• Smart Information Delivery
• SIOS
• Building technology - Siemens Global
• Smart Information Delivery

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