Siemens RWF55
Burner and boiler controller for temperature or pressure with modulating or two-stage output.
The Siemens RWF55 is a compact universal controller that keeps the boiler temperature or steam pressure on setpoint by driving a modulating or two-stage burner. This Modbus RTU template reads the actual value, active setpoint, inputs, actuator position and alarm states, and lets you set setpoints, PID parameters and remote operation from ModbusCloud.
- Protocol
- Modbus RTU
- Connection
- RS485, 4800 baud
- Registers
- 66, read and write
- Brand
- Siemens
- Key readings
- Actual value · Active setpoint · Outside temperature input · Actuator position · Burner alarm · Output states
- Available commands
- Setpoint 1 and 2 · PID parameters · Switching thresholds · Weather curve · Remote setpoint
- Compatible models
- RWF55.50A9 · RWF55.51A9 · RWF55.60A9 · RWF55.61A9
- Last updated
Registers (66)
66 read, 53 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Analog Input 1 | Read | ||||
| Actual Setpoint | Read | ||||
| Analog Input 2 | Read | ||||
| Analog Input 3 | Read | ||||
| Analog Input 3 Unfiltered | Read | ||||
| Actual Angular Positioning | Read | ||||
| Burner Alarm | Read | ||||
| Outputs And States | Read | ||||
| Binary Signals And Hardware | Read | ||||
| Setpoint 1 | Read and write | ||||
| Setpoint 2 | Read and write | ||||
| Proportional Band | Read and write | ||||
| Derivative Time | s | Read and write | |||
| Integral Action Time | s | Read and write | |||
| Dead Band | Read and write | ||||
| Actuator Running Time | s | Read and write | |||
| Switch On Threshold Heating | Read and write | ||||
| Switch Off Threshold Stage 2 Heating | Read and write | ||||
| Switch Off Threshold Heating | Read and write | ||||
| Switch On Threshold Cooling | Read and write | ||||
| Switch Off Threshold Stage 2 Cooling | Read and write | ||||
| Switch Off Threshold Cooling | Read and write | ||||
| Response Threshold | Read and write | ||||
| Outside Temperature Point 1 | °C | Read and write | |||
| Boiler Temperature Point 1 | °C | Read and write | |||
| Outside Temperature Point 2 | °C | Read and write | |||
| Boiler Temperature Point 2 | °C | Read and write | |||
| Display Start Input 1 | Read and write | ||||
| Display End Input 1 | Read and write | ||||
| Start Value Input 2 | Read and write | ||||
| End Value Input 2 | Read and write | ||||
| Setpoint Limit Low | Read and write | ||||
| Setpoint Limit High | Read and write | ||||
| Offset Input 1 | Read and write | ||||
| Offset Input 2 | Read and write | ||||
| Offset Input 3 | Read and write | ||||
| Ramp Function | Read and write | ||||
| Ramp Slope | Read and write | ||||
| Ramp Tolerance Band | Read and write | ||||
| Ramp Limit Value | Read and write | ||||
| Remote Detection Timer | s | Read and write | |||
| Filter Constant Input 1 | Read and write | ||||
| Filter Constant Input 2 | Read and write | ||||
| Filter Constant Input 3 | Read and write | ||||
| Working Range Low | Read | ||||
| Working Range High | Read | ||||
| Alarm Relay Function | Read and write | ||||
| Alarm Relay Limit | Read and write | ||||
| Alarm Relay Hysteresis | Read and write | ||||
| Remote Operation | Read and write | ||||
| Controller Off In Remote | Read and write | ||||
| Remote Switch On Threshold | Read and write | ||||
| Remote Switch Off Threshold Down | Read and write | ||||
| Remote Switch Off Threshold Up | Read and write | ||||
| Remote Setpoint | Read and write | ||||
| Remote Burner Release | Read and write | ||||
| Remote Relay K2 | Read and write | ||||
| Remote Relay K3 | Read and write | ||||
| Remote Relay K6 | Read and write | ||||
| Remote Step Control | Read and write | ||||
| Remote Positioning Output | Read and write | ||||
| Remote Switch On Threshold Cooling | Read and write | ||||
| Remote Switch Off Threshold Down Cooling | Read and write | ||||
| Remote Switch Off Threshold Up Cooling | Read and write | ||||
| Software Version | Read | ||||
| VdN Number | Read |
Loading registers…
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Show boiler temperature, setpoint and burner position of every heating plant on one dashboard.
- Get an email alert when the burner alarm word is not 0 or the actual value leaves its band.
- Compare actual value and setpoint in the history to check the tuning of the PID loop.
- Change setpoint 1 from ModbusCloud for a night setback or a seasonal change.
- Track output states to count burner starts and second stage running per day.
Installation
Connect the RS485 terminals of the RWF55 to the RS485 port of the ModbusCloud Gateway, with a 120 ohm terminator at the bus ends.
In the configuration level ConF > IntF, set the device address and baud rate, for example 19200.
In ModbusCloud, add a Modbus device with the same address and baud rate and import this template.
Check that Analog Input 1 and Actual Setpoint match the red and green display of the controller.
Things to watch for
The controller does not answer. What should I check?
Check address and baud rate in ConF > IntF; the factory setting is 4800 baud and address 1. Try 8N1 first, as parity is not documented. Swap A and B if needed. While the USB setup port is connected, the RS485 interface is inactive.
Why do values show strange decimals or huge numbers?
The values are 32-bit floats. If you entered registers by hand, use two registers per value and check the word order. Inputs follow the decimal place and scaling set on the controller, so 62.5 on the display is 62.5 in ModbusCloud.
My written setpoint is replaced after a while. Why?
In remote operation the controller uses the remote setpoint and falls back to local mode when no message arrives within the remote detection timer. Write Setpoint 1 for a permanent change, or keep writing the remote setpoint within that time.
What should I know before writing parameters?
Writes go straight into the boiler controller. A wrong threshold, proportional band or setpoint limit can cause short cycling or overheating. Agree changes with the boiler engineer, write one value at a time and check the result on the display.
Want to see how it works?
