Both Satel ABAX2 and Ajax Jeweller operate at 868 MHz, use AES-128 encryption, and serve the professional European security and building automation market. Choosing between them affects KNX integration reliability, cloud dependency, sensor portfolio, and certifications. Here is a direct technical comparison.

Protocol Specifications

Satel ABAX2 (ACU-280): 868.0 MHz GFSK, bidirectional TDMA, 3-second polling cycle, AES-128 per-device key. Up to 150 devices per ACU-280. RS485 bus to INTEGRA alarm panel. Fully local, no internet required. EN 50131 Grade 3 (ACU-280 with INTEGRA 128). Open-air range: 500-800m.

Ajax Jeweller (Hub 2 Plus): 868.0-868.6 MHz GFSK, bidirectional TDMA, Wings 2.4 GHz for config/OTA. 100 devices per hub, up to 25 hubs per site. Ethernet + dual SIM (LTE/2G). API requires cloud connectivity (ajax.systems servers). EN 50131 Grade 3 (Hub 2 Plus). Open-air range: 2000m (factory specification).

Range in Real Buildings

Ajax Jeweller consistently outperforms ABAX2 in multi-floor buildings with reinforced concrete slabs. Ajax published 2000m range implies approximately 85-90 dB link budget vs ABAX2 ACU-280 approximately 70 dB. Through two concrete floors (30 dB each): Ajax maintains 25-30 dB margin, ABAX2 drops to borderline 10 dB.

Both systems offer repeaters: ABAX2 ARU-100 (one hop, DIN rail mains-powered), Ajax ReX (up to 2 hops per sensor, also mains-powered). In practice, one Ajax ReX per floor in a concrete building reliably covers all sensors. With ARU-100, ABAX2 matches performance in most scenarios.

KNX Integration Comparison

ABAX2 to KNX: local integration via INTEGRA INT-RS relay outputs (dry-contact to KNX binary input, response under 100ms, no network) or ETHM-1 Plus TCP API to Home Assistant KNX bridge (LAN-only, 0.5-1s latency). Zero cloud dependency. Works when internet is down, router is down, or LAN is partially degraded.

Ajax to KNX: REST API webhooks via ajax.systems cloud. Event chain: sensor trigger -> Hub 2 Plus -> ajax.systems server -> webhook POST to your Node-RED server -> KNX telegram. Typical total latency: 1-3s. Outage of ajax.systems = no KNX events. No local API available (as of 2027). For critical security-to-KNX automation (trigger alarm relay on intrusion), this cloud dependency is a design concern in EN 50131 Grade 2+ installations.

Verdict: ABAX2/INTEGRA is the correct choice for any installation where KNX integration must be reliable without cloud. Ajax is acceptable for non-critical occupancy hints or environmental monitoring where 1-3s latency is not a problem.

Sensor Portfolio

ABAX2 strengths: AMD-200 dual-tech PIR+microwave with anti-mask (detects spray paint or foam on lens), ATD-100 glass break, ASW-210 wireless output module (control locks or actuators over ABAX2). Mature portfolio, all sensors in production for 5+ years, proven in Central European security installations.

Ajax strengths: MotionCam (PIR + integrated camera, sends photo on trigger to monitoring centre), DoorProtect Plus (contact + shock + tilt), FireProtect Plus (smoke + CO + heat in one device), WaterStop (motorised water valve, remotely closes water main on flood detection). Photo verification is Ajax's unique differentiator — monitoring centres receive a photo with each alarm, reducing false dispatch by 60-80%.

EN 50131 Certification

ABAX2 ACU-280 + INTEGRA 128: EN 50131-1 Grade 3 (high-risk premises, requires keypad + remote confirmation for arm). Suitable for bank branches, high-value retail. ABAX2 sensors individually EN 50131-2-2 Grade 2.

Ajax Hub 2 Plus: EN 50131-1 Grade 3 with Ajax OS version 2.28+. Ajax sensors: EN 50131-2-2 Grade 2 (most sensors), Grade 3 (MotionCam Outdoor). For Grade 3 full system certification: requires Hub 2 Plus + Ajax PRO Desktop monitoring connection + Grade 3 sensors throughout.

Use Case Decision Guide

Choose ABAX2 when: KNX must work offline; existing INTEGRA panel; Polish, Czech, or Baltic market installer; Grade 3 needed with dry-contact-to-KNX reliability; integration with wired INTEGRA zones required.

Choose Ajax when: photo-on-trigger required by insurer or monitoring centre; multi-floor concrete building where range is critical; rapid deployment without alarm panel programming; client uses Ajax PRO Desktop monitoring platform; non-critical automation (occupancy, temperature) where cloud latency is acceptable.

Both can coexist: ABAX2/INTEGRA for security zones (offline-reliable KNX integration), Ajax for environmental and occupancy sensors (cloud API to Node-RED KNX bridge for non-critical automation). This hybrid is increasingly common in Baltic premium residential projects.