Ultra-Low Power, Wireless RTU Data Logger - Infinite ADU-500

The ADU-500 Data Logger is an ultra-low power, wireless RTU with data logging and alarming capabilities. The battery-powered RTU integrates two analog inputs, three digital inputs, one pulse counter input and several excitation options for powering measuring transducers. The device aids the acquisition of up to 48 measurement channels, based on the common SDI-12 communication protocol. The ADU-500 uses an internal 3G cell modem to automatically transmit data and alerts. A D-size Lithium Thionyl battery can deliver autonomous operation for more than 10 years.

  • Two analog inputs, three digital inputs, and one pulse counter input
  • Operating temperature: -40 to 65 °C
  • Multiple excitation options for external sensors
  • SDI-12 sensor data acquisition
  • Internal Li battery
  • Maintenance free operation for over 10 years

Applications include:

  • Environmental monitoring
  • Water resources management
  • Weather conditions monitoring

The Infinite Advantage

The ADU-500 utilizes a dual processor architecture so as to integrate extreme low-power consumption with advanced processing and communication features. A system controller (ultra-low power MCU) performs the data logging, measurement and alarm condition detection on a systematic basis. A robust communication processor, turned on and off by the system controller, performs data processing and regulates communications via the internal wireless Modem. The outcome is up to 50% power saving compared to similar other units while performing the same tasks.

Measurements and Data Logging

The system controller scans the digital inputs for detecting an alarm condition. Analog input gain, scaling, and alarm limits are user definable. The analog inputs and SDI-12 sensors are sampled based on the user-defined sampling rate. Sampling rate and sampling duration impact the battery life according to the transducer power supply needs.

SDI-12 Serial Bus

The SDI-12 is an asynchronous, ASCII, serial communications protocol that was developed for smart sensory instruments that usually monitor environmental data. The communication is accomplished by digital communications. The addressing system permits the data recorder to communicate with numerous microprocessor-based sensors over a single line. The ADU-500 adheres to the SDI-12 Standard Version 1.2 and supports comprehensive commands for sensor configuration, in terminal mode. The ADU-500 can gather data from multiple SDI-12 sensors for a total amount of 48 measurement channels.


The ADU-500 supports acquisition from sensors with an RS-485 interface, using the widely used MODBUS ASCII protocol. About 10 measurement channels from a number of sensors are supported.

Transducer Excitation

The unit offers several excitation options for measuring transducers.

Alerting and Messaging

SMS announcements include periodical Status messages and alert messages for confirming unit availability. The unit supports discrete alerting for numerous users. Message texts can be defined by the user.

Data Transmission

The ADU-500 Data Logger supports frequent data transmission according to parameters defined by the user. The unit can transmit data via SMS to predefined users or to an internet server via FTP.

Setup and Remote Configuration

The unit can be programmed locally via the serial port or remotely via SMS by using basic ASCII configuration commands. The command set features commands for configuring input alarm parameters, timing parameters, scaling parameters and alarm limits, and defining user groups. The ADU-500 can be remotely reconfigured by conveying configuration commands to the unit during the regular status message processing.

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