Arcus-eds
ARISTO KNX Visualisation Server — BewO Scripting, BACnet/IP and REST API
Arcus-eds (Aachen, Germany, founded 2000) manufactures the ARISTO KNX server — an embedded Linux DIN-rail device that provides web-based building visualisation, BACnet/IP server, REST API, and BewO scripting language for KNX building logic. The ARISTO monitors all KNX group addresses via KNXnet/IP, generates energy reports, and presents a browser-accessible floor plan interface for building operators. It is a cost-effective alternative to the Gira X1 homeserver and Loxone Miniserver in the German DACH market for mid-size commercial buildings.
Role in our panels
How we use Arcus-eds
ARISTO hardware: ARISTO (standard, ARM Cortex-A8, 512MB RAM, 4GB flash, DIN-rail 35mm, 24V DC, no active cooling), ARISTO plus (Intel x86-64, 8-core, SSD 64GB, for large buildings 500+ devices). Both run Arcus-eds embedded Linux. Connections: Ethernet RJ45 (KNXnet/IP tunnelling + visualisation web server + BACnet/IP), USB (commissioning, log export), internal KNX TP bus port (optional direct TP connection, no separate IP router needed). Web interface: HTML5, responsive, works on tablet/smartphone without native app. Browser: Chrome/Firefox/Safari. ARISTO supports up to 10,000 KNX group addresses (ARISTO plus: 50,000). Users: up to 50 concurrent web sessions. BewO scripting language: BewO (Building-engine-Words) is Arcus-eds's proprietary scripting language for building logic — runs on ARISTO, accesses KNX group addresses by GA name. Example BewO script: IF GA("5/1/0") = 1 AND TIME > "23:00" THEN SET GA("5/2/0") = 0 ENDIF (if office presence = 1 after 23:00, set lights off). Time schedules: SCHEDULE "Monday–Friday 08:00" SET GA("7/0/0") = 1. Alarm logic: IF GA("9/8/0") > 1000 THEN ALARM "CO2 Level High" TO EMAIL "[email protected]". Math functions, averaging, trending graphs. BewO is simpler than IP-Symcon scripting but less powerful than Loxone — suitable for engineers comfortable with basic scripting. BACnet/IP server: ARISTO exposes all KNX group addresses as BACnet objects (Analog Input/Output, Binary Input/Output, Analog Value) — each GA mapped to a BACnet object ID. BACnet/IP server accessible from BMS (Desigo CC, Trend IQ4, Honeywell EBI) over Ethernet. This bridges KNX residential/small commercial devices (switches, actuators, sensors) to BACnet BMS used in large commercial buildings. Max BACnet objects: 5,000 (ARISTO standard), 25,000 (ARISTO plus). BACnet COV (Change of Value) subscription: ARISTO pushes updates to BMS when KNX GAs change — no polling required. BACnet read/write: BMS can write to KNX GAs via BACnet output objects. REST API and hotel PMS integration: ARISTO REST API (HTTP GET/POST, JSON) reads and writes KNX GAs from external systems. Integration examples: hotel PMS (Protel, Fidelio Opera) → HTTP POST to ARISTO → set KNX HVAC setpoint or lighting scene for arriving guest room. ERP energy system → ARISTO REST → daily energy Wh totals per zone for ISO 50001 report. ARISTO is also a KNX visualisation choice in Germany and Austria for school energy management — displays energy use per classroom, generates weekly PDF reports.
KNXnet/IP server providing web visualisation, BACnet/IP bridge, REST API, and BewO scripting — connects KNX infrastructure to BACnet BMS, hotel PMS systems, and energy management software.
Used in these project types
Arcus-eds products
Key components we install
ARISTO KNX server (ARM, standard)
KNXnet/IP visualisation server with BACnet/IP, REST API, BewO scripting, up to 10K GAs
ARISTO plus KNX server (x86, high-performance)
8-core x86 ARISTO for large buildings — 50,000 GAs, 25,000 BACnet objects, SSD storage
ARISTO DALI gateway module
DALI-2 master module for ARISTO server — 64 DALI devices per line, ETS6-free configuration
ARISTO analogue I/O extension
4× 0–10V analogue input and 4× relay output for sensors and actuators without KNX bus
ARISTO visualisation software licence
Floor plan editor, graphic elements, trend graphs, alarm management for ARISTO web interface
Arcus-eds FAQ
How does ARISTO compare to Gira X1 homeserver?
ARISTO and Gira X1 are both KNXnet/IP visualisation servers. ARISTO advantages: BACnet/IP server built-in (Gira X1 has no BACnet), REST API (Gira X1 has limited external API), more open BewO scripting. Gira X1 advantages: polished UI editor (QuadClient), better end-user app experience, wider installer recognition in Germany. ARISTO is preferred in commercial/BMS-connected projects; Gira X1 in residential and light commercial.
Does ARISTO need a separate KNX IP router?
Not necessarily. The ARISTO has a built-in KNXnet/IP tunnelling interface — connects directly to the KNX IP infrastructure line (requires KNXnet/IP routing via main line coupler). The optional internal KNX TP port (ARISTO-TP variant) also allows direct TP bus connection as a line coupler, eliminating the need for a separate IP router for the server connection.
What programming knowledge is needed for BewO scripting?
BewO uses a simple structured English-like syntax — no prior programming experience needed for basic time schedules and IF/THEN logic. For complex calculations (energy averaging, PI control loops), basic programming literacy helps. Arcus-eds provides BewO script library with ready-to-use examples for common building automation scenarios — most ARISTO projects use only 10–20 BewO scripts.
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