COMET P8541 – WebSensor, 4 Channels for External Temperature/Humidity Probes

COMET P8541 – Ethernet WebSensor with 4 Channels for External Temperature/Humidity Probes 

The COMET P8541 is a powerful Ethernet WebSensor (P-Line) with four channels for external temperature and humidity probes – the ultimate solution for comprehensive multi-point monitoring in server rooms, technical rooms, warehouses, clean rooms, production facilities, climate chambers, or anywhere multiple critical points must be monitored simultaneously. With four independent channels, you can measure up to four temperature points or two T+RH combinations, all within one compact device.

The external probes (DSxx series, sold separately) measure temperature up to +105 °C and humidity from 0–100 %RH with highest accuracy. In addition to the primary values, the P8541 automatically calculates all key humidity parameters: dew point, absolute humidity, specific humidity, mixing ratio, and specific enthalpy – all directly available via the integrated web interface or through Modbus TCP.

The large dual-line LCD displays current readings and can be switched off during continuous operation. Via Ethernet (RJ45), the sensor integrates seamlessly into networks, including direct connection to COMET Cloud (3 months free, then 1 Credit/year) for graphs, exports, alarms, and remote access via app or browser. Alternatively, Modbus TCP, SNMP, JSON, or XML support is available for your own SCADA/BMS/IoT solution.

Its robust housing and operating temperature range from –30 to +80 °C (probes up to +105 °C) make the P8541 a reliable partner for tough continuous operation, both indoors and outdoors. The sensor is maintenance-free, long-term stable, and the first choice for modern multi-point monitoring – made by COMET.

Why the COMET P8541 is the professional 4-channel WebSensor:

• 4 independent channels – up to 4 temperature or 2 T+RH probes
• Ethernet interface – direct network connection
• COMET Cloud ready – 3 months free, then affordable
• Modbus TCP, SNMP, JSON, XML – open for third-party systems
• Large dual-line LCD – switchable
• High precision – depending on probe up to ±0.4 °C / ±2.5 %RH
• All humidity parameters integrated – dew point directly available
• Remote alarm function – email, SNMP trap, Syslog
• IP30 protection – for indoor use

Technical Data P8541:

• Temperature range: –55 to +105 °C (depending on probe)
• Humidity: 0 to 100 %RH (depending on probe)
• Accuracy: depending on connected DSxx probe
• Resolution: 0.1 °C / 0.1 %RH
• Measurement interval: 2 s
• Interface: Ethernet (RJ45)
• Cloud: COMET Cloud (3 months free)
• Protocols: WWW, Modbus TCP, SNMPv1, SOAP, XML
• Alarm protocols: email, SNMP trap, Syslog
• Power supply: 5 V DC (PoE optional)
• Operating temperature: –30 to +80 °C
• Protection class: IP30
• Dimensions: 88 × 74 × 39.5 mm
• Weight: approx. 135 g
• Warranty: 3 years

Perfect for:

• Data centers & server rooms (multi-point climate monitoring)
• Technical & heating rooms
• Warehouses & production halls
• Clean rooms & pharmaceutical production
• Building automation & BMS systems
• Multi-point monitoring
• Integration into existing networks
• Quality assurance & process control

Installation & Start-up – completed in minutes

Mount the device, connect network cable and power, place up to 4 probes – done! The integrated web interface guides you through the setup. Online in seconds with COMET Cloud – no server needed.

Summary:

• Four-channel P-Line WebSensor
• Supports temperature and humidity probes
• Remote alarm

Scope of Delivery:

• P8541
• User manual
• Traceable calibration certificate
• Free TSensor software for transmitter configuration
• COMET Cloud for 3 months
• External probes are not included
• Power supply is not included