AVW200 2-Channel Vibrating-Wire Analyzer Module
Greatly Reduces Signal Noise
Spectral analysis plus high resolution result in better readings
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The AVW200 is a vibrating-wire analyzer module that allows our dataloggers to measure vibrating-wire strain gages, pressure transducers, piezometers, tiltmeters, crackmeters, and load cells. These sensors are used in a wide variety of structural, hydrological, and geotechnical applications because of their stability, accuracy, and durability.

The AVW200 uses vibrating-wire spectral-analysis technology (VSPECT™). VSPECT observes the incoming sensor signal, performs a Fourier transform and a spectral analysis (transforming the time series into indivdual sinusoidal components in the frequency spectrum), and determines the sensor frequency by identifying the largest signal in the acceptable range while filtering out environmental and electrical noise.

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Benefits and Features

  • Provides better measurements by significantly reducing incorrect readings caused by noise sources
  • Interfaces two vibrating-wire sensors; more sensors may be connected if an AM16/32B multiplexer is used
  • Self-checking diagnostics give continual feedback on sensor condition
  • High resolution—less than 0.001 Hz (industry standard is 0.1 Hz)
  • Low current drain
  • Interfaces both temperature and frequency measurements from vibrating-wire sensors


Detailed Description

The AVW200 uses an innovative spectral-interpolation method for measuring the sensor’s resonant frequency. With the spectral interpolation method, the analyzer module excites the vibrating-wire sensor, measures the response, performs a Fourier transform on the response, and returns the result with a resolution better than 0.001 Hz—all within two seconds. Because spectral analysis can distinguish signal from noise on the basis of frequency content, this method offers improved immunity to competing noise.

The AVW200 analyzer module also provides many self-checking diagnostics such as vibrating-element signal strength, signal-to-noise ratio, vibrating-element signal decay ratio, and incorrect signal response. These diagnostics can be running in the background to give continual feedback of the condition for each sensor.


Number of Vibrating-Wire Sensors Measured Up to 2 vibrating-wire sensors can be connected to the analyzer module. Additional sensors can be measured by using an AM16/32-series multiplexer.
Power Requirements 9.6 to 16 Vdc
Analog Input/Outputs 2 differential (DF) vibrating-wire measurements (V+ and V-) and 2 single-ended (SE) ratiometric resistive half-bridge measurements (T+ and T-) for vibrating-wire sensor's onboard temperature sensor.
Digital Control Ports 3 digital control ports (C1 – C3)
  • C1 functions as an SDI-12 I/O communication port.
  • C2 functions as a Clk output for multiplexer control.
  • C3 functions as a reset output for multiplexer control.
RS-232 Port 1 9-pin RS-232 port (for connecting to a datalogger COM port)
Measurement Resolution 0.001 Hz RMS (±250 mV differential input range; -55° to +85°C)
Measurement Accuracy ±0.013% of reading (±250 mV differential input range; -55° to +85°C)
Input Voltage Range ±250 mV (differential)
Common Mode Range ±25 V
Baud Rates Selectable from 1200 to 38.4 kbps. (ASCII protocol is one start bit, one stop bit, eight data bits, and no parity.)
  • Either 128 or 512 kB of SRAM
  • 2 MB of OS Flash
CE Compliance Standards to which Conformity Is Declared IEC61326:2002
Dimensions 21.6 x 11.18 x 3.18 cm (8.5 x 4.4 x 1.25 in.)
Weight 0.43 kg (0.95 lb)

Typical Current Drain @ 12 Vdc

Quiescent ~0.3 mA
Active RS-232 Communication ~6 mA
Measurement ~25 mA



The AVW200 Vibrating-Wire Spectrum Analyzer Module allows our dataloggers to measure vibrating-wire strain gauges, pressure transducers, piezometers, tiltmeters, crackmeters, and load cells.

Datalogger Considerations

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X CR300 Series

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR5000 CR7X CR9000
* * * *

Datalogger Notes:
*The CR10(X), CR23X, and CR5000 support the SDI-12 mode only.

Enclosure Considerations

The AVW200 requires a desiccated, non-condensing environment. A Campbell Scientific enclosure is recommended when the analyzer module is in the field. The AVW200 has built-in keyhole flanges for mounting to an enclosure backplate.

Compatible Enclosures

ENC10/12 ENC10/12R ENC12/14 ENC14/16 ENC16/18 ENC24/30 ENC24/30S
# # #

Enclosure Notes:
#If using the RS-232 port, the AVW200 must be mounted flat to fit in an ENC10/12, ENC10/12R, or ENC12/14.

Power Considerations

The AVW200 is typically powered by the datalogger's power supply.


AVW200 OS v.06 (551 KB) 06-10-2016

Current AVW200 firmware. Use the Device Configuration Utility version 1.13 or greater to send firmware and to configure the AVW200.

View Update History

Frequently Asked Questions

Number of FAQs related to AVW200: 9

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  1. The AVW200-series modules are not required, but they do reduce the chance of erroneous readings by filtering electrical noise that is sometimes present.

  2. The AVW200 must be wired directly to the datalogger via a cable.

    The AVW206, AVW2011, and AVW216 have built-in spread-spectrum radios tuned to different frequencies that allow the datalogger to communicate with a remote AVW device through an appropriate radio link.

  3. Two probable causes are the following:

    • The SerialOpen() instruction has not been added to the datalogger code.
    • The correct PakBus address setting has not been used in the AVW200 instruction.
  4. It takes 2 s for the AVW200-series modules to acquire a measurement from each sensor. An AVW200-series module servicing two AM16/32B multiplexers, each with 16 vibrating-wire sensors, requires approximately 64 s to acquire data.

  5. Two multiplexers, each with a maximum of 16 or 32 sensors per multiplexer, can be attached. If temperature measurements are excluded from each sensor, 32 sensors are possible.

  6. Dozens of AVW200-series modules can be accessed through one CR1000. The limiting factor is the frequency at which the CR1000 is set to retrieve data from each module. If the CR1000 needs to collect data very frequently from the modules, fewer AVW200-series modules can be accommodated in the time between data collection events.

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