Description

The DataTaker DT85G is an intelligent, low-power, and highly rugged data logger specifically optimised for geotechnical and structural monitoring applications.

An overview of its core capabilities, features, and technical specifications includes the following:

Key Geotechnical Focus

While it shares the same base architecture as the standard DT85, the “G” variant features a built-in vibrating wire infrastructure. This makes it a go-to choice for challenging environments like dams, tunnels, mining operations, and landslide prevention sites.

Here is a comprehensive breakdown of its key features, capabilities, and specifications:

1. Core Geotechnical Capabilities

The standout feature of the DT85G is its specialised support for Vibrating Wire (VW) sensors, which are heavily relied upon in civil engineering for their long-term stability.

• Vibrating Wire Support: It has specialised onboard circuitry to pluck and read vibrating wire sensors (measuring strain, pressure, or displacement) over a frequency range of 500 Hz to 5 kHz.
• Capacity: It features 5 analogue channels capable of reading up to 16 vibrating wire sensors with temperature compensation (thermistors), or up to 48 vibrating wire sensors if temperature compensation isn’t required.
• Sensor Compatibility: Direct support for Extensometers, Piezometers, Inclinometers, Strain Gauges, Pressure Cells, Crack Meters, and Tiltmeters, as well as Carlson, Electrolevel, and LVDT devices.
• Broad Compatibility: It integrates seamlessly with major geotechnical sensor brands (e.g., Geokon, Slope Indicator, RST Instruments, Soil Instruments, Roctest).

Universal Analog & Digital Channels

The DT85G features a unique Dual Channel Isolation Technology, allowing you to configure the terminals in different ways depending on your sensor wiring requirements.

Base analogue Channel Configuration

• 16 Channels: If using 3-wire or 4-wire isolated inputs (ideal for vibrating wire sensors with built-in temperature compensation/thermistors).
• 32 Channels: If configured for 2-wire isolated inputs.
• 48 Channels: If configured for 2-wire common reference inputs (ideal for vibrating wire sensors without thermistors).

Other Input Channels

Dual Serial Sensor Ports

The logger separates its serial tasks into two dedicated hardware connections:

• The Serial Sensor Port: This is a fully programmable, universal terminal port that can be hardware-configured for RS232, RS422, or RS485 communication. It is designed to poll data directly from smart sensors, flow meters, or gas analysers.
• The Host RS232 Port: Nominally used to connect the logger to a PC or a remote cellular modem (supporting full hardware handshaking lines like RTS/CTS, DTR, DSR, DCD). However, if needed, you can free this port up and program it to act as a second RS232 serial sensor channel.

Both ports support flexible baud rates ranging from 300 to 115,200 baud.

Native Protocol Support

Rather than just capturing raw text, the DT85G natively processes standard serial communication protocols:

• Modbus RTU (Master & Slave): The logger can act as a Modbus Master to actively poll industrial registers from external devices (like power meters or weather stations), or act as a Modbus Slave so a SCADA system can poll the logger’s own recorded data.
• SDI-12 (Serial Digital Interface at 1200 Baud): It features 4 dedicated SDI-12 inputs (shared with the digital channels). This can be useful for environmental and geotechnical monitoring, as a single SDI-12 channel can daisy-chain multiple specialised smart sensors (like multi-depth soil moisture probes, weather stations or water quality sensors) on a single cable run.

Digital Inputs

• Digital I/O: Features 8 bi-directional digital channels, high-speed counters, and 1 latching relay output to trigger external alarms or control hardware.

 

Further Expansion

If your project scales up, the DT85G supports the CEM20 (Channel Expansion Module).

• By chaining expansion modules, the logger can be scaled up to 300 channels (with temperature compensation) or up to 960 channels (without temperature compensation).

Universal Sensor Support & I/O

Beyond vibrating wire sensors, the DT85G functions as a completely universal industrial logger:

• Analog Inputs: It can measure voltage (±30 mV to ±50 VDC), current (±30 mA), resistance (up to 1 M Ohms), and standard frequency. This covers thermocouples, RTDs, strain gauges, and 4-20mA loops.
• Digital I/O: Features 8 bi-directional digital channels and dedicated high-speed counters (up to 4 channels or 2 phase encoders).
• Programmable Analogue Output: Includes 1 programmable output channel (voltage or current) for easy integration into SCADA systems.

4. Data Storage & Communications

• Internal Memory: Standard 128MB internal storage, capable of holding approximately 10 million data points (expandable up to 2GB via upgrades).
• Web Interface (dEX): The built-in dEX software operates entirely through a standard web browser over an Ethernet or USB connection. It allows you to configure tasks, mimic dashboards (dials, bar graphs, charts), and view real-time data without needing proprietary host software.
• Robust Networking Protocols: Supports Modbus (for industrial control), FTP/SFTP (to automatically push data to your server), HTTP, XML, and SMTP (for email alerts/alarms).
• Physical Ports: 1x Ethernet, 1x USB host port (for easy thumb-drive data retrieval), 1x RS232 port with modem support.

Power & Physical Build

• Rugged Construction: Built with a solid, anodised aluminium powder-coated casing capable of operating in extreme conditions (typically rated from –45°C to 70°C).
• Power Requirements: Accepts 10–30 VDC external input.
• Internal Backup: Features an internal 6V rechargeable lead-acid backup battery to maintain operation during external power cuts.