Siemens Rwf40 Manual May 2026

Experienced technicians often overlook the "General Notes" section, but it contains gold:

| Parameter | Name per Manual | Typical Value | Explanation | |-----------|----------------|---------------|--------------| | InP1 | Input 1 type | Pt100 or 4-20 | Defines sensor type. | | dEC | Decimal point | 0 or 1 | Resolution (0 = whole number, 1 = one decimal). | | SCL | Scale low | 0.0 | Minimum process value (e.g., 0°C). | | SCH | Scale high | 200.0 | Maximum process value (e.g., 200°C). | | Cntr | Control type | 3p or 2p | 3p = three-position step control (most common); 2p = two-position. | | t1 | Actuator run time | 30 seconds | Time for actuator from 0 to 100%. |

Pro tip from the manual: For three-position step control (modulating motors), always ensure t1 matches your actuator’s datasheet. A mismatch causes hunting (oscillation).

If you are looking at the manual and see an option for "SSR" or a wiring diagram showing a connection to a "Solid State Relay," that is the solid feature. It is the controller's ability to precisely modulate power through a modern, non-wearing electronic switch.

The Siemens RWF40 Go to product viewer dialog for this item.

is a compact universal digital controller designed for controlling temperature or pressure in heat-generating plants, typically in connection with modulating or multistage burners . It is often integrated by OEMs into larger systems like boilers or feedwater control setups . Core Technical Manual Content

Official technical literature from sources like SCC Combustion and Thermal Solutions typically includes the following sections: RWF40... Compact Universal Controllers - Thermal Solutions

The Siemens RWF40 is a compact universal digital controller designed primarily for managing boiler temperature or pressure in heat-generating plants. It is widely used by original equipment manufacturers (OEMs) for burner control and supervision. Official Manuals & Technical Resources

Technical User Manual (Full): Comprehensive instructions for commissioning, setting parameters, and troubleshooting software versions 126.01.02 and 126.02.01.

Data Sheet & Overview: Provides technical specifications and functional descriptions for OEM integration.

Programming & Hints Guide: A quick-reference "hints" manual for common scaling parameters like SCL (Scale Low) and SCH (Scale High).

Modbus Interface Guide: Detailed documentation for the RS-485 serial port and data transmission settings. siemens rwf40 manual

Replacement Guide (RWF40 to RWF5x): Instructions for upgrading older RWF40 units to the newer RWF50 or RWF55 series. Key Features & Functions

Control Modes: Supports 2-stage or modulating operation to maintain specific temperature or pressure setpoints.

Display: Features dual 4-digit 7-segment displays; the red display shows the actual value, while the green display shows the setpoint.

Inputs: Includes three analog inputs for boiler temperature (Pt100, Ni100), external setpoints, and outside temperature (weather-dependent shifting).

Connectivity: Equipped with an RS-485 serial port for integration into data networks using the Modbus protocol.

Mounting: Designed for control panel installation with dimensions of 96 x 48 x 127.5 mm. Quick Setup Parameters

Commonly adjusted parameters found in the configuration level include:

Siemens RWF40 is a compact universal controller primarily used for boiler temperature and pressure regulation in heat-generating plants. Depending on your specific technical needs, there are several "helpful papers" and manuals available: Thermal Solutions LLC Core Manuals & Technical Literature Complete User Manual

: This is the primary document covering installation, electrical connections, operating modes (like low-fire and modulating burner operations), and parameter configuration. Thermal Solutions: RWF40 User Manual (PDF) Kingstec: Data/Landis RWF40 (PDF) Technical Data Sheet

: Ideal for a quick overview of dimensions, wiring terminals (screw terminals at the rear), and electrical specifications such as AC 100...240 V mains voltage. Thermal Solutions: RWF40 Tech Brochure (PDF) Specialized "Helpful" Papers Hints Manual

: This condensed guide is highly recommended for technicians; it focuses on specific scaling parameters like (Scale Low) and (Scale High) for analog inputs, and setpoint limits ( SCC Combustion: RWF40 Hints (PDF) Calibration & Calibration Guide Pro tip from the manual: For three-position step

: Useful for step-by-step instructions on setting PID parameters, manual burner control, and using the self-setting (auto-tuning) function. Scribd: RWF 40 Modulator Calibration Guide RS-485 Modbus Interface

: Essential if you are integrating the controller into a data network via MODbus protocol (RTU mode). Thermal Solutions: RWF40 Modbus Interface (PDF) Key Operating Modes Explained RWF40... Compact Universal Controllers - Thermal Solutions

The Siemens RWF40 is a compact universal digital controller specifically designed for the temperature and pressure control of heat-generating plants, such as modulating or multistage burners. Primary Functions and Features

The RWF40 provides precise PID control with various output and input options tailored for industrial boiler applications:

Operating Modes: Features an "Auto Tune" PID output control for self-setting parameters, as well as a manual operating mode.

Dual-Stage Control: In 2-stage operation, it provides control based on set switching thresholds, acting as a thermostat or pressurestat in low-fire mode.

Displays: Equipped with two 4-digit 7-segment displays: red for the actual value and green for the setpoint.

Connectivity: Optional RS-485 interface supports MODBUS protocol (RTU mode) for data network integration.

Inputs: Includes three analog inputs (e.g., for Pt100, thermocouples, or standard signals) and two binary inputs for operating mode or setpoint changeover. Technical Specifications Specification Mains Voltage AC 100...240 V ±10%, 50...60 Hz Power Consumption Approx. 8–10 VA Housing Dimensions 96 x 48 x 127.5 mm (for flush panel mounting) Protection Degree IP 65 (Front), IP 20 (Base) Mounting Orientation Operating Temp -20°C to +50°C Installation and Wiring Guidelines

Safety: Electrical connections must be performed by authorized staff only. Double-pole isolation must be provided before working on live parts.

Terminals: Connections are made via screw terminals at the rear of the unit. If you are looking at the manual and

Mounting: The unit is designed for flush panel mounting. Ensure national safety regulations are complied with during installation. Configuration and Manual Operation Interface RS-485 RWF40... - Thermal Solutions Boiler

Rather than just summarizing the manual, this feature is designed as an interactive troubleshooting & configuration guide for technicians and engineers.

Buried in the service level (press P and + simultaneously for 5 seconds) is the FAC parameter. The manual explicitly warns:

Setting FAC = 1 and confirming will erase every custom parameter and restore Siemens factory settings. Use only as a last resort.

After a factory reset, you must re-enter InP1, SCL, SCH, Cntr, and t1.

The most anxiety-inducing part of any burner start-up is the purge cycle. We trust the controller to not blow the door off the boiler room. The manual gives us a peek into why we can trust it.

The RWF40 doesn't just look at the flame detector; it manages the air/fuel ratio during the pre-ventilation and ignition phases. The manual breaks down the "Vr" (Pre-ventilation) and "t3" (Pre-ignition) times.

But look closely at the fault codes section. The logic is designed to differentiate between a "flame failure" during operation and a "no flame establishment" during start-up. The manual shows that the controller treats these as two completely different physics problems. One implies a sensor drift or fuel supply issue; the other implies a potential accumulation of unburnt fuel. The controller’s logic handles the latter with immediate lockout—prioritizing safety over convenience.

The RWF40 includes two configurable alarm relays. According to the manual (Section 7.3), common alarm configurations include:

Manual note on hysteresis: Parameter ALH sets the alarm hysteresis (typically 2-5% of scale). Without sufficient hysteresis, alarms chatter.