GP1 Data Logger

    How to Buy
GP1 2 – Green label – smaller file – CopyGP1 3 – Green label – smaller file – CopyGP1 4 – Green label – smaller file – CopyGP1 5 – Green label – smaller file – Copy


  • High accuracy 7 channel data logger
  • 600,000 readings
  • Free use of DeltaLINK-Cloud data sharing service
  • Smart relay control

DeltaLINK‐Cloud – free online data service

The GP1 Data Logger is a complete logging solution housed in a waterproof IP67 enclosure with battery power. The internal memory can hold >600,000 readings – more than enough for one year’s operation (typical).

The GP1 can log up to:

  • 2 differential analogue voltages
  • 2 temperature channels
  • 2 pulse counters

As well as being a powerful general purpose logger, the GP1 is ideal for soil moisture applications and can log:

  • 2 soil moisture sensors e.g. ThetaProbes or SM150Ts
  • 2 temperature probes
  • 2 pulse counters (e.g. rainfall or water meter)
  • 1 WET Sensor

The optional GP-PBA-X50 Precision Bridge Adapter enables a GP1 to log up to 2 bridge sensors such as pressure transducers and strain gauges.

When connected to 1 or 2 ThetaProbes or SM150T Soil Moisture Sensors, the GP1 Logger provides simple high accuracy recording of moisture content (as well as rainfall and temperature).

Irrigation control

The GP1 Data Logger, running DeltaLINK Software, can control irrigation directly from the soil moisture (and/or rainfall and/or temperature) or act as a sophisticated interface between these sensors and many types of programmable timer.

Start and Stop control levels can be separately configured and there’s even an option for pulsing the output when it’s desirable to match the water application rate to the soil’s infiltration capacity.

NB: Our GP2 Advanced Data logger and Controller offers even more advanced irrigation control capabilities.

DeltaLINK PC Software

DeltaLINK PC Software is supplied free with all GP1, GP2 and DL6 data loggers. DeltaLINK allows you to set up the logger input channels and recording parameters, check readings from connected sensors, and collect & display data.

  • Clear graphic display
  • Full configuration

Storage, communications and power

1 MB of FLASH memory enables storage of 600K readings (typical). Data can be collected by a laptop locally via RS232 or via USB (USB to RS232 Adaptor Cable type USB-RS232 required), or remotely using the cellular modem options.

The GP1 has 1 PP3 internal battery as standard. Up to 10 GP1s can share power and communications using an M8 cabling network. GP2 Data Loggers can be integrated into such a network via an adapter cable.


Soil Science, Plant Physiology, Agronomy, Climate Research and Meteorology
Horticulture, Agriculture, Turf and Gardens-Amenity Landscaping




Input connections2 voltage channels
2 temperatures or 2 additional SM150T Sensors [3]
2 counters (33 kHz & 50 Hz)
1 WET Sensor
Control outputs1 relay (1 A)
Readings stored600,000
Recording rate1 second to 24 hours
Communication optionsRS232 USB [1] or modem
Sensor excitation1 switched logger power
15 V precision reference
Power9 V 6LR61 (PP3) alkaline or external power 11-24 V
Battery life (dependent on usage)>76k readings
lasting >130 days
Enclosure ratingIP67
Temperature range-20 to +60°C
Size140 x 105 x 45 mm
Typical applicationsMonitoring soil moisture
General data logging
Controlling irrigation


Sensor compatibility (maximum number of sensors that could be connected [2]
ML3✓ (2) with temp ✓ (4) excl. temp [3]
SM150T✓ (2) with temp ✓ (4) excl. temp [3]
PR2 SDI-12
WET Sensor✓(1)
EQ3✓(2 as mV only)
Tensiometers (bridge sensors)✓(2) each requires GP-PBA-X50
Counters or Events✓(2) 1 fast 1 slow
Relay Output✓(1)


[1] With USB to RS232 Adapter Cable type USB-RS232

[2] With appropriate expansion cards and power supply arrangements

[3] Temperature channels provide only single-ended inputs so should not be used with long cables or in noisy environments when used with soil moisture sensors. The accuracy figures quoted for GP1 soil moisture readings do not apply to these resistance channels when configured as soil moisture inputs.


For full GP1 specification please see the GP1 data sheet or Quick Start Guide

Product Resources

Data Sheets

Case Studies



Technical Notes


Regulatory Information