Buderus
GB192 condensing boilers with Logamatic EMS bus Modbus KNX integration
Buderus, Europe's oldest heating manufacturer (owned by Bosch since 1999), supplies GB192 and GB212 gas condensing boilers to German residential and commercial markets. EMS plus bus bridging enables KNX integration for modern smart building projects.
Role in our panels
How we use Buderus
The GB192 and GB212 condensing boilers use the Bosch EMS plus (Energy Management System) proprietary 2-wire bus architecture for all communication between the boiler, Logamatic controller, room units, and system accessories. EMS plus operates at 9600 baud over a polarity-independent 2-wire connection — physically similar to RS-485 but using Bosch-proprietary framing. All Buderus Logamatic RC series room controllers (RC300, RC310) and zone modules (MM100) communicate exclusively via EMS bus. Bridging EMS to Modbus RTU requires a dedicated EMS-to-Modbus adapter. The Buderus MX25 adapter (or third-party Esbe or Iventum converters) sits on the EMS bus and presents a Modbus RTU slave at 9600 baud on a separate RS-485 port. Available Modbus registers: boiler flow setpoint (Reg 1), boiler return temperature (Reg 2), operating mode (Reg 100 — values: 0=off, 1=manual, 2=auto, 3=DHW only), fault code (Reg 200), and gas consumption (Reg 201, in kWh × 10). This approach is functionally identical to Viessmann ViCARE Modbus integration since both use the Bosch EMS bus architecture. A Moxa NPort 5110 serial-to-Ethernet converter takes the Modbus RTU output from the MX25 adapter and presents it as Modbus TCP on port 502 over Ethernet. This stage enables any Modbus TCP-capable KNX gateway (Intesis IN701KNX, LOYTEC LGATE-952) to access the full Buderus register map from the KNX panel DIN rail without an RS-485 cable run to the gateway. The Moxa NPort is DIN-rail mountable and powered from the panel 24V DC supply. The Intesis IN701KNX gateway configuration maps Modbus TCP registers to KNX group addresses: flow setpoint GA (DPT 9.001), operating mode GA (DPT 5.001), fault code GA (DPT 1.005 binary fault flag, plus DPT 5.005 fault code value for diagnostics), and gas consumption GA (DPT 13.013 for BREEAM Ene 02 sub-metering). The fault code GA triggers a KNX alarm function in Gira HomeServer or MDT IP Interface for maintenance notification. Comparison with Viessmann ViCARE: both use identical Modbus register addresses via EMS adapter — projects switching between Buderus and Viessmann require no KNX gateway reconfiguration, only EMS adapter replacement.
Buderus uses the Bosch EMS plus (Energy Management System) proprietary 2-wire bus. An EMS-to-Modbus RTU adapter (Buderus MX25 or third-party Esbe/Iventum converter) bridges EMS to Modbus RTU at 9600 baud. A Moxa NPort 5110 then converts RTU to Modbus TCP. The Intesis IN701KNX maps registers to KNX: flow setpoint GA (DPT 9.001), operating mode GA (DPT 5.001), fault code GA (DPT 1.005), gas consumption GA (DPT 13.013). Integration is functionally identical to Viessmann ViCARE Modbus since both use Bosch EMS bus.
Used in these project types
Buderus products
Key components we install
GB192i 35kW
Wall-hung gas condensing boiler, up to 35 kW (available in 15, 19, 24, 30, 35 kW variants). ErP A-rated. Integral EMS plus bus connection for Logamatic controller and MX25 Modbus adapter. DHW indirect heating via external cylinder (no combi — cylinder sensor input for plate heat exchanger control). Suitable for single-family residential to small commercial. For KNX integration: connect MX25 adapter to EMS bus (2-wire, polarity-independent), Moxa NPort to MX25 RS-485 output, Intesis IN701KNX to Moxa TCP output — all DIN-rail mounted in same panel.
WPL AR 14
Air/water air-source heat pump 14 kW heating capacity. Part of the Buderus/Bosch heat pump range alongside Stiebel Eltron OEM products. SG Ready S1/S2 inputs for KNX PV surplus relay control — wiring identical to Stiebel Eltron WPL. Optional ISG web Modbus TCP module available (same hardware as Stiebel Eltron ISG web). In mixed projects combining GB192 boiler with WPL AR heat pump (bivalent system), the panel includes both MX25 EMS adapter (for boiler) and ISG web Modbus TCP (for heat pump) connected to single Intesis IN701KNX gateway.
MX25 Adapter
EMS plus to Modbus RTU bridge adapter. Connects to EMS bus 2-wire (clamp connection, polarity-independent) and presents Modbus RTU slave on RS-485 port at 9600 baud, 8N1. Registers: flow setpoint (1), return temp (2), outdoor temp (3), mode (100), fault code (200), gas consumption (201 kWh × 10). DIN-rail mount, 24V DC powered. Used in all Buderus KNX integration projects as the essential EMS-to-Modbus bridge before Moxa NPort Ethernet conversion stage.
Logamatic RC310
Room controller with EMS plus bus connection to GB192. Controls multiple heating circuits with weather compensation (requires outdoor sensor). Stores boiler settings and heating curves. Displays flow temp, return temp, DHW temp, outdoor temp. Can coexist with KNX integration via MX25 — the KNX setpoint write via Modbus overrides RC310 manual setpoint. Used as local user interface alongside KNX automation; RC310 provides direct physical control for occupant override without requiring access to KNX visualisation.
CS10 Module
Cloud connectivity module for GB192 boiler providing REST API access via Buderus MyBuderus app. Separate from MX25 Modbus adapter — can coexist on same EMS bus. Provides manufacturer cloud monitoring for warranty and maintenance scheduling. Not used for KNX integration (REST API is cloud-only, not local). In combined projects, CS10 provides maintenance reporting while MX25 + Intesis handles local KNX automation. Bosch has aligned CS10 firmware with Viessmann ViCARE for unified Bosch group remote monitoring.
Buderus FAQ
Is Buderus the same as Viessmann for KNX integration?
Both Buderus and Viessmann use the Bosch EMS plus bus architecture — the integration approach is nearly identical. Both require an EMS-to-Modbus RTU adapter (Buderus MX25 or Viessmann equivalent), followed by Moxa NPort RS-485/TCP conversion, followed by Intesis IN701KNX gateway. The Modbus register addresses for flow setpoint (1), mode (100), fault (200), and gas consumption (201) are the same on both brands. Projects that switch between Buderus and Viessmann boilers require only replacement of the EMS adapter hardware — no KNX gateway reconfiguration.
What Modbus registers are available via the Buderus MX25 adapter?
The MX25 adapter exposes these key Modbus RTU registers: Reg 1 (boiler flow setpoint, °C × 10), Reg 2 (boiler return temperature, °C × 10), Reg 3 (outdoor temperature from sensor, °C × 10), Reg 100 (operating mode: 0=off, 1=manual, 2=auto, 3=DHW only), Reg 200 (fault code, 0=no fault), Reg 201 (gas consumption kWh × 10). Via Moxa NPort and Intesis IN701KNX, these map to KNX group addresses with appropriate DPTs for setpoint control, mode selection, fault monitoring, and BREEAM energy sub-metering.
Does the Buderus WPL AR heat pump support SG Ready for KNX PV control?
Yes — the Buderus WPL AR heat pump range (Bosch/Stiebel Eltron OEM) includes SG Ready S1/S2 dry contact inputs on the control PCB. KNX relay actuator wiring is identical to Stiebel Eltron WPL: S1 (terminal 31) and S2 (terminal 32) controlled by two MDT BJ65-AB08.01 relay channels. Four SG Ready states are selectable from KNX PV surplus logic. For bivalent GB192+WPL AR projects, the panel includes both MX25 EMS adapter (boiler Modbus) and SG Ready relay wiring (heat pump), both integrated to the same KNX automation system.
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