COMET U3121 – Compact Data Logger for External Temperature and Humidity Probes

COMET U3121 – compact data logger for external T+RH probe (Digi/E), temperature & humidity according to probe specification, dew point, 500,000 values memory 

The COMET U3121 is the compact and reliable data logger specially designed for external temperature-humidity probes (Digi/E series) – the ideal solution for precise long-term monitoring and documentation of temperature, relative humidity, and dew point in climate chambers, storage areas, cold chains, incubators, dryers, server rooms, greenhouses, pharmaceutical production, or anywhere humidity and temperature are critical and must be recorded. With a large memory of 500,000 values (non-cyclic) or 350,000 values (cyclic), freely adjustable recording interval (1 s to 24 h), and traceable calibration certificate (EN ISO/IEC 17025), it is perfect for quality management, audits, and ISO compliance.

The external Digi/E probe (sold separately) measures temperature and humidity (measuring range & accuracy depending on probe, typically -30 to +105 °C / 0–100 %RH). The dew point is calculated automatically (according to probe specification, typically ±1.5 °C at T<25 °C and RH>30 %). The acoustic and optical alarm (buzzer + LED) immediately warns when freely adjustable limits are exceeded. Min/Max values are stored. The backlit LCD display is easy to read, and the measurement/alarm update interval is adjustable (1 s, 10 s, 1 min). The logger operates independently with a 3.6 V AA lithium battery – lifetime several years depending on interval. No power supply required – ideal for fixed and mobile installations. Recording non-cyclic (stops when memory is full) or cyclic (overwrites oldest data). Real-time clock with date/time. Data transfer via USB-C to PC (COMET Vision software).

The data logger is maintenance-free, long-term stable, and comes with a 3-year warranty. The included traceable calibration certificate ensures the highest measurement accuracy from the factory. Intuitive operation via buttons and a clear menu. Whether used as a stand-alone logger in the system, as a mobile tester in service, or as a fixed component in the process chain – the U3121 impresses with precision, robustness, and ease of use. The external probe (sold separately) allows measurements in pipes, ducts, or narrow spaces.

Why the COMET U3121 is the best data logger for external T+RH probes:

• External T+RH input (Digi/E series) – flexible measurement anywhere
• 500,000 value memory – non-cyclic or cyclic
• Recording interval freely adjustable – 1 s to 24 h
• Acoustic & optical alarm – instant warning at limit exceedance
• Min/Max memory – extreme values per channel
• Backlit LCD – temperature, humidity, and status readable
• Traceable calibration certificate included – EN ISO/IEC 17025
• Self-contained battery operation – lithium AA, several years of operation
• USB-C data transfer – easy reading via COMET Vision
• 3-year warranty – COMET quality guaranteed

Technical data U3121:

• Temperature: according to connected Digi/E probe
• Humidity: according to connected Digi/E probe
• Dew point: according to connected Digi/E probe
• Resolution: 0.1 °C / 0.1 %RH / 0.1 °C dew point
• Channels: 1× connectable temperature+humidity probe
• Memory: 500,000 values (non-cyclic) / 350,000 values (cyclic)
• Recording interval: 1 s to 24 h
• Measurement/alarm update: adjustable 1 s, 10 s, 1 min
• Alarm: acoustic (buzzer) + optical (LED) at limit exceedance
• Display: backlit LCD
• Power supply: 3.6 V AA lithium battery
• Operating temperature: -20 to +60 °C
• Protection rating: IP20
• Dimensions: 61 x 93 x 32 mm
• Weight (incl. battery): approx. 120 g
• Warranty: 3 years

Perfectly suited for:

• Climate chambers and incubators
• Storage and cold room monitoring
• Pharmaceutical and food production
• Greenhouses & agriculture
• Server rooms and data centers
• Production and process monitoring
• Quality management & audits
• Independent long-term logging without mains connection

Installation and operation – done in minutes

Connect the external Digi/E probe, insert the battery – done! Set intervals and limits, start logging – read data via USB-C. The backlit display and the acoustic/optical alarm make operation safe and convenient. Calibration certificate included – ideal for audits and quality management.

Summary:

• The data logger is designed for recording temperature and humidity via external probes
• Data is stored in non-volatile electronic memory
• Data can be transferred to a PC via USB-C
• When limits are exceeded, alarms are indicated by LED, LCD, and acoustic signal
• The temperature and humidity probe is not included
• Probes in suitable lengths and versions are available as optional accessories
• The device includes a traceable calibration certificate declaring metrological traceability of the standards in accordance with EN ISO/IEC 17025 requirements.

Scope of delivery:

• U3121
• User manual
• Traceable calibration certificate
• 1× 3.6 V lithium battery
• Free full version of COMET Vision analysis software
• External probes not included
• USB communication cable not included