COMET U3631M – IoT Wireless Datalogger with 2G Modem, Internal Temperature and Humidity Measurement, External Pt1000 Sensor

COMET U3631M – IoT Wireless Datalogger with 2G Modem, internal T+RH (-20 to +60 °C ±0.4 °C / 0–100 %RH ±1.8 %), external Pt1000 (-90 to +260 °C ±0.2 °C), dew point, SMS/JSON alarm 

The COMET U3631M is a reliable IoT wireless datalogger with an integrated 2G modem (Quad-Band GSM/GPRS) – a fully autonomous solution for remote monitoring and long-term recording of temperature, relative humidity, and dew point using internal sensors and an external Pt1000 temperature probe. Whether for cold chains, warehouses, climate chambers, server rooms, greenhouses, compressors, dryers, pharmaceutical production, or remote sites – the U3631M immediately sends SMS and JSON alarms via GPRS when thresholds are exceeded. Regular JSON data transmission to the COMET Database or COMET Cloud (a complete monitoring, alarm, and analysis tool) can be configured. Local alarms are indicated via LED, LCD, and buzzer. With a memory capacity of 1 million values (non-cyclic) or 600,000 values (cyclic) and a traceable calibration certificate (EN ISO/IEC 17025), it is perfect for quality management, audits, and ISO compliance.

The internal sensors measure temperature from -20 to +60 °C (±0.4 °C) and humidity from 0 to 100 %RH (±1.8 %RH within 0–90 % at 23 °C). The dew point is automatically calculated (-90 to +60 °C, ±1.5 °C at T<25 °C and RH>30 %). The external Pt1000 input measures from -90 to +260 °C (±0.2 °C from -50 to +100 °C, ±0.2 % of reading above that, ±0.4 % from -90 to -50 °C). Acoustic and optical alarms alert instantly when freely programmable limits are exceeded. Min/max values are recorded. The backlit LCD display provides clear readability, and logging rate (0.7 to 5 s) as well as display refresh intervals are user-adjustable. The logger operates fully autonomously on an internal battery – no external power required. Data can be downloaded to a PC via USB-C. COMET Cloud: 3 months free, then 1 credit per year. The quad-band GSM modem (850/900/1800/1900 MHz) ensures global coverage and reliable data transmission.

The datalogger is maintenance-free, long-term stable, and comes with a 3-year warranty. The included traceable calibration certificate guarantees the highest measurement accuracy from the factory. Configuration is simple via LCD or COMET Cloud. Whether used as a mobile remote logger at construction sites, a stationary monitor in remote installations, or a central unit in production – the U3631M excels in precision, autonomy, 2G connectivity, and ease of use. The external Pt1000 probe (sold separately) allows measurements in pipes, ducts, or confined spaces.

Why COMET U3631M is the best IoT 2G datalogger for T+RH with external probe:

• Integrated 2G modem (Quad-Band GSM/GPRS) – SMS/JSON alarm & data transmission without WLAN/LAN
• Internal T+RH sensors + external Pt1000 input – dual temperature measurement
• 1 million data memory – non-cyclic or cyclic
• COMET Cloud – full monitoring, alarm & analysis (3 months free)
• Acoustic/optical alarm + LED – immediate on-site warning
• Dew point & all humidity calculations – automatic
• Backlit LCD – all values displayed simultaneously
• Traceable calibration certificate included – EN ISO/IEC 17025
• Battery-powered autonomy – no external power needed
• 3-year warranty – guaranteed COMET quality

Technical data U3631M:

• Internal temperature: -20 to +60 °C (±0.4 °C)
• External temperature (Pt1000): -90 to +260 °C (±0.2 °C from -50 to +100 °C / ±0.2 % above / ±0.4 % from -90 to -50 °C)
• Internal humidity: 0 to 100 %RH (±1.8 %RH)
• Dew point: -90 to +60 °C (±1.5 °C at T<25 °C and RH>30 %)
• Resolution: 0.1 °C / 0.1 %RH / 0.1 °C dew point
• Alarm: acoustic + optical + SMS/JSON via GPRS
• Memory: 1,000,000 values (non-cyclic) / 600,000 values (cyclic)
• Logging interval: 1 s to 24 h
• Measurement interval / display refresh rate: 0.7 to 5 s
• Display: backlit LCD
• Communication: 2G modem (Quad-Band 850/900/1800/1900 MHz, GPRS Class B) + USB-C
• Power supply: internal battery (life depending on configuration – several months/years)
• Operating temperature: -10 to +60 °C
• Protection class: IP20 (device)
• Warranty: 3 years

Perfect for:

• Cold chains & transport monitoring (temperature & humidity remotely)
• Storage and refrigeration monitoring at remote locations
• Compressed air systems & compressors (remote humidity)
• Pharmaceutical and food production
• Greenhouses & agriculture
• Server rooms and data centers
• Remote monitoring without local internet
• Quality management & audits

Setup and operation – done in minutes

Connect the external Pt1000 probe, insert a SIM card (if desired), activate the battery – done! Configure intervals, limits, and Cloud/SMS settings, start logging – retrieve data via COMET Cloud or USB-C. The backlit display and acoustic alarm ensure safe and comfortable use. Calibration certificate included – ideal for audits and quality management.

Summary:

• The GSM datalogger records temperature and humidity using internal sensors, plus temperature via an external probe
• When preset limits are exceeded, SMS and JSON messages are sent via GPRS data connection
• Measured data can be transmitted to COMET Cloud – a comprehensive monitoring, alarm, and analysis system
• Regular transmission of JSON messages to the COMET Database can also be configured; transmission interval is adjustable
• Local alarms indicated via LED, LCD, and internal acoustic signal
• Recording stored in non-volatile electronic memory
• Data can be transferred to a PC via the supplied USB-C cable
• The GSM recorder includes a traceable calibration certificate with declared metrological traceability according to EN ISO/IEC 17025
• When purchasing a new IoT wireless datalogger with integrated modem, you receive 3 months of free COMET Cloud access; continued full use requires 1 credit per year.

Scope of delivery:

• U3631M
• User manual
• Traceable calibration certificate
• Rechargeable battery
• Power adapter
• USB-C cable
• Free full version of COMET Vision analysis software
• COMET Cloud for 3 months
• External probes not included
• SIM card not included