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HD33MT.4 – Data Logger

Make: Delta Ohm                                        Model: HD33MT.4
✅ Datalogging of temperature, relative humidity, dew point temperature, atmospheric pressure, solar radiation, rainfall amount, wind speed and direction
✅ Available in two versions: with input for standard RS485 MODBUS-RTU sensors or with inputs for dedicated Delta OHM sensors
✅ GSM/GPRS module for remote monitoring
✅ Data sending via email, FTP and to an HTTP server (e.g. Delta OHM Cloud)
✅ Can be powered by mains or photovoltaic panel (with optional external power supply unit)
SKU: DL-HD33MT.4-DEL Category:

HD33MT.4– Data Logger:

The HD33[L]MT.4 data logger is specifically designed for use in weather stations. Many types of sensors can be connected thanks to its standard terminal header inputs. The data logger is equipped with:
• 4 analog independently configurable inputs (0…50 mV, -50…+50 mV, 0…1 V, 0…10 V, 0…20 mA or 4…20 mA, Pt100, Pt1000, thermocouple, potentiometer, pyrgeometer).
• 2 voltage-free counting contact inputs (e.g. a tipping bucket rain gauge and a cup anemometer can be connected).
• One RS485 port with Modbus TCP/IP (via an optional module for the connection to an ETHERNET network) or Modbus-RTU protocol, configurable as “Master” or “Slave”.
• One SDI-12 “Master” port compatible with version 1.3 of SDI-12 protocol.
• 2 voltage-free contact alarm outputs.
On request, input with M12 connector for relative humidity and temperature with NTC sensor combined probe or, alternatively, for temperature only probe with NTC sensor.

HD33MT.4 is the most universal compact meteorological data logger series with a universal 4G/3G/2G/GPRS modem. This logger is designed to run on solar power and has a very low power consumption; a solar charger and regulator are already built into the logger. Just add a solar panel and a rechargeable battery, and you are independent of any further power source. But, of course, it can also be powered directly from a power supply if that is more convenient.

This logger has multiple inputs and outputs: 4 analog independently configurable inputs, 2 voltage-free counting contact inputs, an SDI-12 “Master” port compatible with version 1.3, an RS485 port Modbus-RTU configurable as “Master” or “Slave,” Ethernet MODBUS TCP/IP (optional as HD33MT.4/E or HD33LMT.4/E), and 2 voltage-free contact alarm outputs. Optionally, on request, an internal atmospheric pressure sensor can be added to the logger. As the electronic circuits for this are already integrated, this will not influence the number of free inputs available. The modem will step down (from 4G to 3G to 2G) when a certain network is not available. Standard without display; ordering code HD33LMT.4 with the display.

Depending on the sensors connected, simultaneous monitoring of temperature, humidity, dew point, atmospheric pressure, solar radiation, amount of rain, wind speed, and direction.

Application and features of HD33MT.4– Data Logger:



✅ Environmental monitoring
✅ Industrial health and safety
✅ Energy efficiency management
✅ Farming
✅ Urban planning
✅ Meteorological research
✅ IP 65 housing
✅ Optional custom LCD
✅ It can be powered by mains (with optional external power supply unit) or by a solar panel
✅ Low power, it can operate for weeks even in absence of recharging of the internal battery
✅ Internal clock of high accuracy and stability, with possibility of automatic time
✅ synchronization with an HTTP or NTP reference server

Delta ohm




4G / E version equipped with 4G + ETHERNET

Power Supply

If integrated battery is used: 18…28 Vdc (externally powered) or 12 Vdc (photovoltaic panel)
If integrated battery is not used: 7…28 Vdc (externally powered)

Power Consumption

< 5 mA during measurement / < 1 A peak during GSM activity

Integrated lead acid battery


Switched power supply output

Active only when external sensors have to be powered


External, included

Measuring & logging Interval

1, 2, 5, 10, 15, 30 seconds / 1, 2, 5, 10, 15, 30, 60 minutes

Internal Memory

Circular management or stop logging if memory is full

Number of samples (depending on the number of the detected quantities)

From 242,850 to 858,070


Sending of alarm e-mail and SMS. Two voltage-free (NO) contact alarm outputs.

Operating Conditions

-40…+70 °C / 0…100 %RH without display, -20…+70 °C / 0…100 %RH with display

Internal clock

High stability ± 2 ppm (0…+40°C)/± 5 ppm (-40…+70°C)


Optional custom LCD

Connection to PC

USB port with mini-USB connector – Free software


270 x 170 x 110 mm

Protection Degree



– 4 analog standard inputs
– 2 voltage free contact inputs
– 1 RS485 MODBUS-RTU input
-1 SDI-12 input
– 1 passive T/RH probe

Atmospheric Pressure

Optional internal sensor


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