Honeywell Contact Interface - Model 72641A2

The Challenge: Integrating Legacy and External Systems

Modern IP Nurse Call Systems, such as the Ackermann Systevo, must often communicate with external, non-proprietary devices like fire alarm panels, older security systems, or loud conventional bells/sirens (horns) designed for facility-wide notification. The major challenge is translating the digital signals and data bus protocols of the Systevo system into simple, universal dry contact closures—the language external devices understand—without compromising the integrity or compliance of the primary nurse call network.

The Solution: The 72641A2 Isolation and Relay Module

The Honeywell Contact Interface, Model 72641A2, is the precise digital-to-analog gateway required for seamless interoperability. Functioning as a Relay Module/Contact Interface, the 72641A2 receives coded instructions from the Systevo Data Bus (DBUS) and isolates the system to provide potential-free (dry) contact outputs. This feature enables the activation of external visual or audible signaling devices (bells, horns, or general alarm lights) based on specific event triggers within the nurse call system.

Technical Deep Dive: Interoperability and Scalability

1. Digital-to-Analog Translation and Isolation

• Potential-Free Contacts (Dry Contact Output): The module provides contacts (typically Normally Open - NO, and Normally Closed - NC) that are electrically isolated from the nurse call system. This is crucial for connecting external devices operating at different voltages (ee.g., 24V or 110V AC) without risking damage or interference to the sensitive low-voltage Systevo network.

• Event-Specific Activation: The 72641A2 can be programmed via the central control unit to activate its relays only for specific, high-priority events (e.g., Emergency Call, Code Blue, or Fire Panel Interface), ensuring external alarms are reserved only for true emergencies.

2. Architectural Flexibility and Expansion

The module is designed for flexible deployment to expand the reach and capability of the nurse call system.

• DBUS Integration: Like all Systevo components, the 72641A2 connects directly to the Data Bus (DBUS), allowing it to be addressed, configured, and monitored centrally. This simplifies installation and ensures high reliability.

• Multiple Relay Outputs: (Assuming standard configuration for a robust interface) The unit typically features multiple independent relay outputs (e.g., 2 to 4 relays), allowing it to control several different external devices simultaneously (e.g., one relay for a corridor horn, another for a security system contact).

3. Compliance and Status Monitoring

• System Monitoring: The unit's status is continuously monitored by the central Systevo system via the DBUS. Any failure or loss of communication with the 72641A2 is immediately reported, maintaining compliance with VDE 0834 standards regarding system integrity.

• Simplified Maintenance: By centralizing the interface function, maintenance and troubleshooting of external alarm triggers become significantly simpler and faster.

Summary of Specifications (Honeywell 72641A2)