CDM-A108 8-Channel 5 V Analog Input Module
24-Bit Resolution
Greatly increases sensor capacity
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The CDM-A108 is an analog input module that allows you to easily expand your Campbell Scientific datalogging system. The CDM-A108 features a 24-bit, analog-to-digital converter and a low-noise, analog front-end to provide you with superior analog measurements. This module also supports period average measurements and includes both current and voltage excitation channels.

The CDM-A108 has eight differential inputs and two excitation channels. It provides both a 12 V and a switched 12 V port for powering your peripherals and two switched 5 V ports for peripheral control.

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Benefits and Features

  • Ability to make simultaneous measurements


Front tilt view
Front tilt view
Front tilt view
Front view
Front view
Front tilt view
Front tilt view
Back view
Left view
Right view
Top view
Bottom view
Using a screwdriver for wiring purposes
A datalogger measuring CDM devices natively without the need for an SC-CPI

Detailed Description

The CDM-A108 offers 24-bit sigma-delta Adc with 16 user programmable notch frequencies from 30,000 Hz to 2.5 Hz, including 50 and 60 Hz. Previous generations of dataloggers could notch out 50 or 60 Hz.

General Purpose Outputs for AM16/32B Control or Sensor Power

SW5V Outputs

  • Number of Outputs: 2
  • Output Resistance: 40 Ω

SW12V Outputs

  • Number of Outputs: 1
  • Typical Limit: 200 mA
  • Minimum Limit: 180 mA

12V Outputs

  • Number of Outputs: 1
  • Typical Limit: 200 mA
  • Minimum Limit: 180 mA


-NOTE- Additional specifications are listed in the CDM-A108 and CDM-A116 brochure.
Power Requirements 9.6 to 32 Vdc voltage
Estimated Accuracy
  • ±(0.04% of reading + offset) 0° to 40°C
  • ±(0.06% of reading + offset) -40° to +70°C
  • ±(0.08% of reading + offset) -55° to +85°C
Mounting Standard 1-in. grid (DIN rail mounting available)
Operating Temperature
  • -40° to +70°C (standard)
  • -55° to +85°C (extended)
Number of Channels 8 differential or 16 single-ended
Maximum Multiplexed Sample Rate 3.0 kHz (using fast [100 μs] input setting)
Maximum Burst Sample Rate 30 kHz
Input Range ±5000 mV, ±1000 mV, and ±200 mV
Period Averaging Traditional period averaging on analog input channels
CPI For datalogger connection. Baud rate selectable from 50 kbps to 1 Mbps. (Allowable cable length varies depending on baud rate, number of nodes, cable quality, and noise environment, but can be as long as 700 m under proper conditions.)
USB USB 2.0 full speed connection available for attaching to a PC. (Port is used to configure the module and download updates via our Device Configuration Utility.)
Warranty One year against defects in materials and workmanship
Dimensions 20.3 x 12.7 x 5.1 cm (8 x 5 x 2 in.)

Typical Current Drain

Sleep <1 mA
Active 1 Hz Scan 2 mA (estimated)
Assumes one single-ended measurement with the first notch frequency (fN1) at 30 kHz
Active 20 Hz Scan 20 mA Assumes one single-ended measurement with the first notch frequency (fN1) at 30 kHz

Voltage/Current Excitation Outputs

Voltage Excitation ±5 V (@ 50 mA)
Current Excitation ±2.5 mA (±5 V compliance voltage)
Number of Voltage/Current Excitation Outputs 2


The CDM-A108 is compatible with the CR6 datalogger. To use the CDM-A108 with a CR1000, CR800, CR850, or CR3000 datalogger, a SC-CPI (datalogger-to-CPI interface) must be used between the datalogger and the CDM-A108. 


CDM-A100 OS v.03 (596 KB) 10-03-2017

Execution of this download installs the CDM-A108 / CDM-A116 Operating System on your computer which can then be uploaded to the CDM-A108 or CDM-A116 device with the Device Configuration Utility.

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CPI Calculator v.1.0 (2.49 MB) 07-06-2016

The CPI Calculator is a downloadable Microsoft Excel spreadsheet used to estimate the usage and capacity of a CPI network.  The calculator provides an overview on CPI devices including the CDM-A108, CDM-A116, CDM-VW300, CDM-VW305, and the CSAT3B.  The calculator can also estimate the measurement speed of the CDM-A108 and CDM-A116 based on the number of channels and measurement parameters.


The CPI Calculator is an estimation tool and will help you better understand and design CPI networks by considering the following:

  1. What is the capability of each CDM or CPI device
  2. What is the CPI network capacity
  3. How much of the CPI capacity are the CDMs or CPI devices using


Device Configuration Utility v.2.17 (46.4 MB) 02-13-2018

A software utility used to download operating systems and set up Campbell Scientific hardware. Also will update PakBus Graph and the Network Planner if they have been installed previously by another Campbell Scientific software package.

Supported Operating Systems:

Windows 10, 8.1, 8, and 7 (Both 32 and 64 bit)

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