COMET H5421 CO₂ Sensor with External Probe, 2 Relays

COMET H5421 CO₂ Controller External Probe 2 Relays 

The COMET H5421 is a robust CO₂ concentration controller with a remote external probe (1 m cable) designed for use in demanding or aggressive environments. It accurately measures up to 10,000 ppm and automatically switches two powerful relays when threshold values are exceeded – for example, for ventilation, air conditioning, or alarm systems. A 3-color LED indicator (Green/Yellow/Red) and a loud acoustic signal immediately warn of poor air quality.

The external probe allows installation of the electronics outside the measurement area – ideal for humid, dusty, corrosive, or hard-to-access locations such as production halls, warehouses, greenhouses, barns, or technical rooms. The maintenance-free NDIR CO₂ sensor with automatic calibration ensures years of precise performance.

The RS232 interface with Modbus RTU protocol (and Advantech ADAM compatibility) allows easy integration of the H5421 into building automation or monitoring systems. The fully IP65-protected housing withstands even harsh environmental conditions.

Perfect for automatic, energy-efficient ventilation and air quality monitoring in challenging environments.

Why the COMET H5421 is the solution for demanding CO₂ measurement:

• External CO₂ probe with 1 m cable (optional 2/4 m) – electronics safely housed
• Extended range up to 10,000 ppm – suitable for high concentrations
• 2 potential-free relays (2 A / 50 V / 60 VA) – direct control capability
• 3-color LED indicator – instantly visible
• Integrated acoustic alarm – switchable
• RS232 Modbus RTU – compatible with many systems
• Maintenance-free thanks to automatic calibration
• Fully IP65 protected – ideal for harsh environments
• Rugged housing – operating temperature from –30 to +60 °C
• 3-year warranty

Technical data:

• CO₂ measuring range: 0 to 10,000 ppm
• CO₂ accuracy: ±(100 ppm + 5% of measured value) at 25 °C and 1013 hPa
• CO₂ resolution: 1 ppm
• External probe: 1 m cable
• Relay outputs: 2 × potential-free, max. 50 V / 2 A / 60 VA
• LED indicator: Green ≤1000 ppm | Yellow 1001–1200 ppm | Red ≥1201 ppm
• Acoustic alarm: built-in beeper, switchable
• Communication: RS232, Modbus RTU, Advantech ADAM
• Power supply: 9–30 V DC
• Operating temperature: –30 to +60 °C
• Protection rating: IP65
• Dimensions: 136 × 150 × 45 mm
• Weight: approx. 360 g
• Warranty: 3 years

Perfectly suited for:

• Production halls and workshops
• Warehouses and silos
• Greenhouses and livestock buildings
• Technical rooms and control cabinets
• Humid or dusty environments
• Demand-controlled ventilation in challenging areas
• Monitoring of high CO₂ concentrations
• Industrial and agricultural applications

Installation & commissioning – simple as can be

Mount the electronics housing on the wall, place the external probe, connect relays and power supply, optionally connect RS232 – done. Switching points and alarms can be set via software or directly on the device.

Summary:

• CO₂ level transmitter with two relay outputs
• The device comes with a CO₂ probe and a 1 m cable.
• Green LED on: CO₂ concentration 0 to 1000 ppm
• Yellow LED on: CO₂ concentration 1001 to 1200 ppm
• Red LED on: CO₂ concentration 1201 ppm and higher

Scope of delivery:

• H5421
• User manual
• Traceable calibration certificate
• Free TSensor software for transmitter configuration