Date Published: September 14, 2015
Application: Water & Wastewater
Manufacturer: Isodaq Technology
Measurements: 4-20mA, Flow, SDI-12, Water
Download the PDF version

Isodaq RTU Automatically Transmits Data to PC via GSM/GPRS

isodaqCAS DataLoggers has provided the datalogging solution for a municipal authority collecting hydrologic data from an observation well. The borehole is a shaft 30 feet below ground, down which a sensor has been dangled into the groundwater. The sensor cable leads up into a rectangular hole in the ground that’s a few feet across. The facility’s technician wanted a hydrometric remote telemetry unit which could connect to his SDI-12 output flow meter and water level sensors.

Environmental Monitoring Solution:

The technician sourced an Isodaq Frog RX GSM/GPRS Data Logger from CAS DataLoggers. Equipped with an internal GPS/GPRS modem, the Frog can operate either as a telemetry logger or as a standalone battery-operated datalogger. Isodaq RTU products include models for connection with rain gauges, flow sensors and weather stations. These devices are designed for a wide range of environmental monitoring applications in the water protection, research, and regulatory fields.

The Frog logger is placed near the top of the observation well, a few feet down. Ideal for quick deployment at a low cost, the RTU has standard inputs and a digital event counter. This rugged remote telemetry unit has its own enclosure rated IP68 giving solid protection from the environment and able to withstand temporary submersion. Users can install the Frog RX in a simple meter box or inside a 4-inch tube, with no secondary enclosure required.

The user chose an option for a lead acid cell internal battery pack giving five years operation without replacement, even with daily polling and alarms. Along with the logger’s low-battery alarm, this is very reliable when combined with low-cost GPRS ‘always-on’ protocols.

Hydrometric Sensors:

gps_dataloggerThe Frog RX RTU is a single input datalogger with up to 8 channels and a 4-20 ma analog output as standard. The device offers analog, digital and SDI-12 options for comprehensive environmental monitoring.

  • Sensor 1: Helical flow meter, connected to the Frog’s Channel 1 to measure flow count.
  • Sensor 2: Depth Pressure transmitter, connected to the Frog’s Channel 2+ to measure water level and depth.

The Frog is configured to take a reading from each sensor once every thirty minutes and saves the reading to its internal memory. The data logger can hold over 29,000 16-bit readings, overwriting the oldest data when the storage capacity is full. Flash memory data storage prevents lost data in the unlikely case of battery failure.

Remote Communication:

Equipped with GSM/GPRS communications and an external antenna, the Frog remotely transmits its hydrometric data to the user’s office PC via GPRS once a week. All the data is accessible online from any PC using the manufacturer’s telemetry server.

The Frog is expressly designed to keep deployment and remote outstation maintenance costs as low as possible. With access to all the data online, users don’t have to travel out to the datalogger to collect the data.


Here the user has configured a Low Water Level alarm along with a Pump Failure alarm. Users can also activate a control output to trigger on alarm if required. The Frog also has an alarm hysteresis function and storm rainfall intensity alarm capability for hydrologic applications.

Configuration Software:

gprs_dataloggerThe Isodaq logger also includes free configuration and setup software. Harvest for Windows is provided with all Isodaq models and is available in versions for both Windows (98, 2000, XP, Vista or 7) and Windows Mobile (3, 5 or 6). Harvest takes users through configuration & test for telemetry modems, datalogger setup and setting sample rates and alarms. Operators can export data to CSV or XML format files and graph data for all channels.

RTU Benefits:

Since installation, the station has come to rely on the Frog’s weekly reports. Their technician has all the data for each week on his office PC and can also view it online. This convenience has saved the facility considerable cost formerly spent traveling to devices to manually retrieve data. Meanwhile the Frog can log unattended as a remote outstation owing to its rugged enclosure and battery operation.

Categories Related To This Application

The below links will lead you to a listing of products to the respective category.

Products Related To This Application

Isodaq Technology Frog RX GSM GPRS Telemetry Data Logger

Frog RX

Frog RX GSM GPRS Data Logger

  • Single input logger with up to 8 channels
  • IP68 Rating
  • Lithium Battery Options - up to 5 Year
  • External Antenna
  • Analog, Digital, SDI-12 Input Options
  • 16-bit Accuracy
  • 30K Data Point Storage