Adcon Telemetry provides a wide range of highly accurate sensors to measure weather, soil and water conditions. All sensors can be attached to any Adcon RTU and do not require additional power supply. Sensors range from simple Watermarks to highly sophisticated multi-level soil moisture probes and a state-of-the-art salinity probe.

Development of the A506 SDI-12 adapter interface has opened up the world of digital SDI-12 sensors for Adcon RTUs. This makes a wide range of sensors available, particularly in the environmental sector, from Vaisala's WXT510 All-In-One weather sensor to multi-parameter probes for water quality monitoring.

Our sensors are developed together with world leaders in sensor technology, the best in their fields: Vaisala, Finland, supplies a low-power version of their excellent air temperature and humidity probe, so does Keller of Switzerland, adapting their top-notch pressure transducers to our low power requirements. Our pyranometers feature sensor elements from Kipp & Zonen, The Netherlands, leading manufacture of highly accurate radiation instruments - and there are many more! But they all live to the motto:

Accurate, long term stability, excellent value!

Technical details for the interested reader
All applications supplied by Adcon have one characteristic in common: radio and sensors are permanently and directly exposed to the elements. They are required to operate reliably and accurately at 40 degrees in the shade as well as in arctic conditions. And are still expected to require little or now maintenance and to maintain their accuracy for many years.

This poses quite a challenge for a sensor. What adds to it is the fact that Adcon sensors must operate with very little power, supplied by the RTU's internal battery. Therefore a sensor needs to match the following criteria in order to be selected by our R&D team:

Environmental ruggedness
by default all sensors need to work in an extended temperature range, going down to -30°C. (When you look at some of our sensors - like some rain gauges or water pressure sensors - please bear in mind that water freezes at 0° - so monitoring water levels at -30°C might be difficult. At least on planet Earth...)

Low operating voltage
most Adcon RTU's operate with an internal power pack supplying 5.5 - 7.2V. Since the same voltage is fed to the sensors attached, these need to be capable of operating reliably with such low voltages.

Output signal of 0 - 2.5V
Sensors with 4-20mA or 0-10V output signals usually require operating voltages of 12 - 24V, which would in turn make large batteries and huge solar panels necessary. We have therefore chosen to go for 0-2.5V signals for most RTU's (except A740 addNODE), since these can be fed with 6.2V from our integrated battery packs

Low operating currents
Hand in hand with the low operating voltage our sensors also need to reliable operate with very low current consumption, typically ranging from 3 to 20mA. We recommend to not attach higher loads than 50mA to an A723 addIT respectively 100mA to RTU's of the A733 family.

Settling time of less than 2 seconds
in order to achieve maximum power savings an RTU will completely shut off power supply to the sensors attached after a reading was taken. It is therefore crucial that all sensors require little or now warm-up time after power-up. All our sensors therefore feature extremely short settling times. (exceptions might occur with some water quality sensors, which require heating prior to taking a reading)

SDI-12:
the name is an acronym for "Serial Data Interface with 1.200 baud". This standard communications protocol was developed particularly to interface battery powered recording devices with micro-processor based sensors designed for environmental monitoring. Unlike RS-232/RS-485 devices which usually require proprietary drivers for communication, the SDI-12 protocol ensures compatibility between all sensors and loggers featuring such an interface. If you want to learn more about SDI-12 visit the the website of the SDI-12 Support Group.