The Statox 503 is a DIN-rail gas detection control module by COMPUR Monitors that conditions signals from toxic and combustible gas sensor heads and converts them into relay outputs and a 4–20 mA analog signal for plant control systems. Each module handles one sensor — catalytic bead (Wheatstone bridge), electrochemical, infrared, or PID — with programmable bridge voltage from 2 V to 5.2 V and 4–20 mA sink/source compatibility. Switch-programmable operation lets one module serve as a common alarm master for the entire DIN rail bus.

How does the relay and alarm architecture work?

Three independent relays are provided: Alarm 1 (A1) and Alarm 2 (A2) for user-configurable gas concentration thresholds, and System Failure (SF) which is normally energized and drops out on fault, power loss, or service mode — ensuring fail-safe operation. All three relays are rated 8 A at 250 VAC with silver-nickel contacts. The 4–20 mA analog output transmits the measured gas concentration to a PLC or DCS, with defined states for system failure (0 mA), service mode (2 or 4 mA, programmable), normal measuring (4–20 mA), and over-range (22 mA).

How does the DIN rail bus simplify installation?

Modules connect via a communication bus integrated into the DIN rail mounting — distributing 24 V power and alarm signals across all modules without individual wiring. The six pluggable terminal blocks and hot-swappable design allow modules to be added or removed without shutting down the entire gas detection system or affecting neighboring modules. This modular architecture scales from a single sensor point to multi-point gas detection networks while maintaining SIL 2 functional safety integrity.