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The A755 V2 addSDI GPRS RTU was developed to provide users of SDI-12 sensors with an inexpensive means to log and transmit up to 40 SDI-12 values of environmental data, while at the same time providing 2 pulse inputs, e.g. for water meters and rain gauges, and 2 digital TTL ports which are custom configurable either as in- or as outputs.

Should the GSM network go down or the GPRS connection be interrupted no data will be lost as the A755 features plenty of internal memory. Example: 15-minute data from a multi-parameter water quality sonde with 8 parameters will be stored for about 4 weeks. All functions can be remotely configured through the A850 Gateway. A quad-band GSM/GPRS modem from Telit (formerly Motorola) and a powerful NiMH battery are built-in. The rugged aluminium case has stainless IP-67 connectors and an integrated mast mounting bracket.

Power is supplied by means of a solar panel (e.g. Adcon's 200.733.522 540mA panel) or an external power supply.

  • Applications Weather stations, Soil moisture monitoring, Water Management Science, research & development, and much more.



Case Aluminum, powder coated
Protection class IP-67
Dimensions and weight 160 x 60 x 80 mm / 6.3 x 2.4 x 3.1 inches
1150g / 2.4lb.
Connectors for sensors and power 2 x M9 female 7-pin to sensor
1 x M9 female 5-pin to power
Made in Germany by Binder
IP-67 protection class 
Sockets: brass, nickel plated, with gold plated socket contacts
Protective cap
Antenna connector TNC with external seal, water tight , Made in Germany
Mounting Mast mounting bracket integrated
Operating temperature -20°C ... +65°C / -4°F ... 149°F
-30°C ... +75°C / -22°F ... 167°F extended temp. range upon request


Sensor Input 1 for standard SDI-12 sensors; up to 40 values can be addressed
Counter Inputs 2 for standard reed contacts; electronically debounced, e.g. for rain gauges; max frequency up to 30 pulses per second; min. pulse length 17ms, min. break time 17ms
Digital I/O ports 1 x 3V TTL
1 x 5V TTL
Both I/Os can be configured as either inputs or outputs
Memory 2MB for up to 500.000 readings


Data transmission

Frequencies 900 & 1800 MHz (Europe) and 
850 & 1900 MHz (Americas)
Modem Telit G24L
Telit G24 and H24 upon request
SIM-Cards small footprint
Security SIM-Cards are PIN-Code protected
Connection types - GSM: CSD Circuit Switched Data
GPRS Connection Frequency User selectable:
- permanent connection
- connect from 1 x per minute to 1 x per day
Antenna Omnidirectional, +2dBi, TNC, waterproof



Power supply internal 6.2V battery, charged by solar panel or mains adaptor;
optional: non-rechargeable Lithium-Thionyl battery (to operate the RTU w/o solar panel)
Battery Panasonic high-temperature industrial grade NiMH battery, 3300mAh
Type approvals FCC, R&TTE, CE, Industry Canada, ACMA Australia

Related Categories
Water Quality Multiprobes
Water Level Sensors
Precipitation Sensors
Weather Stations
Soil Moisture
Data Services