The ABB AC/S 1.2.1 Application Controller, BACnet (order code AC/S1.2.1) combines the HVAC automation features of the Basic controller with a built-in BACnet/IP gateway for bidirectional exchange between KNX and building management systems.

Pre-defined modules cover schedules, set points, heat curves, data logging, and device monitoring. Custom modules use the graphical logic editor; the web UI is generated automatically. All engineering stays in ETS.

Key Features

• Built-in BACnet/IP gateway: Bidirectional KNX ↔ BACnet for BMS integration.
• Same HVAC modules as Basic: Schedule, set point, heat curve, logging, device monitoring.
• Graphical logic editor: Create project-specific automation modules.
• Auto-generated web UI: Monitor and manage the KNX system from a browser.
• ETS-only engineering: ETS 5.6.5+ with the ABB AC/S DCA — no extra PC tool required.
• Basic sibling: Without BACnet on-device, see AC/S1.1.1.

At a Glance

Specification	Detail
Product type	KNX Application Controller, BACnet, MDRC
Order code	AC/S1.2.1
Product ID	2CDG110206R0011
Gateway	Built-in BACnet/IP (bidirectional)
Group objects (max.)	2000
Group address assignments (max.)	16000
Automation modules (ASM, max.)	500
Web UI I/O (max.)	30
Auxiliary supply	24 V AC/DC or PoE
Width / weight	4 MW / approx. 192 g
Bus system	KNX TP + BACnet/IP

Technical data, product manual, installation instructions, drawings, EPLAN, ETS app, and declarations are under Downloads.

Applications

• KNX + BMS projects: Map KNX HVAC data to BACnet without an external gateway.
• Central HVAC automation: Plant and room strategies with native BACnet exposure.
• Energy-efficiency programmes: EN 15232 / LEED-oriented control with BMS visibility.
• KNX-only sites: Prefer AC/S1.1.1 when BACnet is not required.

Installation Notes

Mount on a 35 mm DIN rail (4 MW). Connect KNX TP, Ethernet for BACnet/IP, and 24 V AC/DC or PoE. Commission with ETS 5.6.5+ and the ABB AC/S DCA. Use Downloads for manuals and the ETS configuration app.