Description

Increasing the channel capacity of the DataTaker DT80 range is made very easy by adding the DataTaker Channel Expansion Modules (CEM20). The CEM-20 (Channel Expansion Module) is DataTaker’s proprietary relay multiplexer designed to scale up sensor capacity cost-effectively without requiring multiple master loggers.

• How it Connects: A single CEM-20 connects to just one of the master logger’s 4-wire universal analogue channels for data transmission, alongside standard 12V power and digital control lines. The modules can be daisy-chained up to 100 meters away from the host logger.
• Channel Multiplication: Each module adds 20 universal, fully isolated differential channels. Because it inherits DataTaker’s dual-channel isolation technology, each of those 20 channels can be split. A single CEM20 can handle:
  • 20 fully isolated 3-wire or 4-wire inputs (like RTDs or strain gauges).
  • Up to 40 isolated 2-wire inputs.
  • Up to 60 common-reference 2-wire inputs (like single-ended voltages or thermocouples).
• System Limits: * The mid-range DT80 supports up to 5 CEM-20 modules, scaling it to 100 differential channels (up to 300 single-ended inputs).
  • The advanced DT85 supports up to 16 CEM20 modules, turning a single logger into a massive data acquisition node with 320 differential channels (up to 960 single-ended inputs).
• Efficiency: The CEM-20 features ultra-low power consumption. It is automatically powered down by the master logger’s switched 12V output when a sampling schedule is idle, preserving battery life in remote deployments.

The CEM-20 is specifically designed for use with the DataTaker DT80 and DT85 range of data loggers (including DT80, DT80G, DT85, and DT85G series). Please note that it requires Series 2, Series 3, or Series 4 loggers; it is not compatible with the older Series 1 models.

The diagram below shows the required wiring in more detail. In this case a DT80 is shown connected to two CEM-20s. Several K-type thermocouples are also shown, connected to analogue inputs on the CEM-20s and on the logger itself. Using this “dual isolated” method of connecting thermocouples (as per V2 – Independent Voltage Inputs (P181)), up to 86 fully isolated thermocouples could be connected – 40 on each CEM-20 (two per analogue input) plus another 6 on the remaining 3 analogue inputs (inputs 3, 4 and 5) on the DT80.

Omni Instruments can provide enclosures give you the flexibility to install your DataTaker system in a harsh or otherwise unsuitable environment by providing protection against external conditions such as water, dust, and accidental damage. These enclosures are designed to accommodate the DataTaker, channel expansion module and any other equipment required for your system. Enclosure are available for use in industrial, weather proof or portable applications, we can even provide Subsea housing that can be used with the DataTaker logger range for use in the UK Continental Shelf and even for depths up to 4,000m.