AVW211 922 MHz Wireless 2-Channel Vibrating-Wire Interface
Greatly Reduces Signal Noise
Plus includes built-in radio
weather applications supported water applications supported energy applications supported gas flux & turbulence applications supported infrastructure applications supported soil applications supported

Overview

The AVW211 is a vibrating-wire analyzer module that includes an internal 920 to 928 MHz spread-spectrum radio for wireless communication, typically used in Australia and New Zealand. With this vibrating-wire analyzer module, your datalogger can 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.

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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
  • Remote, wireless operation with on-board radio
  • Interfaces both temperature and frequency measurements from vibrating-wire sensors

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Technical Description

The AVW211 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 individual 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.

The AVW211 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.

The AVW211 typically transmits its data to an RF411A spread-spectrum radio that is connected to the data logger. The AVW211 can also be connected directly to the data logger.

Specifications

-NOTE- Electrical specifications are valid over a -25° to +50°C range unless otherwise specified. Non-condensing environment required.
Internal Radio Frequency Range 920 to 928 MHz
Radio Power 250 mW
Older AVW211 analyzer modules (serial # < 11676) have 100 mW radios.
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 data logger 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) for vibrating-wire inputs
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.)
Memory
  • Either 128 or 512 kB of SRAM
  • 2 MB of OS Flash
CE Compliance Standards to which Conformity Is Declared EC61326:2002
Dimensions 21.6 x 11.18 x 3.18 cm (8.5 x 4.5 x 1.2 in.)
Weight 0.43 kg (0.95 lb)

Typical Current Drain @ 12 Vdc

Quiescent, Radio Off ~0.3 mA
Radio Duty Cycling 1 s ~3 mA (includes quiescent current)
Radio Always On ~26 mA (radio transmit current 100 mA)
Active RS-232 Communication ~6 mA (3 s after communication stops, the current will drop to the quiescent current)
Measurement ~25 mA (averaged over the 2 s)

Compatibility

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Dataloggers

Product Compatible Note
CR10 (retired) The CR10 supports the SDI-12 mode only.
CR1000 (retired)
CR1000X
CR10X (retired) The CR10X supports the SDI-12 mode only.
CR200X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired) The CR23X supports the SDI-12 mode only.
CR3000
CR500 (retired)
CR5000 (retired) The CR5000 supports the SDI-12 mode only.
CR510 (retired)
CR800
CR850
CR9000X (retired)

Mounting Equipment

Product Compatible Note
ENC10/12 If using the RS-232 port, the AVW211 must be mounted flat to fit in an ENC10/12.
ENC12/14 If using the RS-232 port, the AVW211 must be mounted flat to fit in an ENC12/14.
ENC14/16

Miscellaneous

Product Compatible Note
ENC10/12R If using the RS-232 port, the AVW211 must be mounted flat to fit in an ENC10/12R.
ENC16/18

Additional Compatibility Information

Sensors

The AVW211 Vibrating-Wire Spectrum Analyzer Module allows our data loggers to measure vibrating-wire strain gages, pressure transducers, piezometers, tiltmeters, crackmeters, and load cells.

Communications

The AVW211's internal spread-spectrum radio can transmit data to an AVW211, RF411A, RF411, or RF431. The AVW211 does not have a transparent mode, and therefore its internal radio cannot communicate with an RF410 radio.

Enclosure Considerations

The AVW211 requires a desiccated, non-condensing environment. A Campbell Scientific enclosure is recommended when the analyzer module is in the field. The AVW211 has built-in keyhole flanges for mounting to an enclosure backplate.

Power Considerations

The AVW211 is typically powered by the data logger's power supply.

Operating System Considerations

Newer analyzer modules with 250 mW radios must use OS 5 or higher for their operating system.

Downloads

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

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

View Revision History

Related FAQs

Number of FAQs related to AVW211: 12

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  1. 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.

  2. 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.

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

  4. 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.
  5. 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.

  6. 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.

  7. No. An AVW206, AVW211, or AVW216 is not capable of communicating with other AVW200-series modules.

  8. Antenna selection depends on multiple criteria: 

    • Consider how many stations a particular station needs to communicate with. For remote stations in communication with only one repeater or base station, a directional or Yagi antenna may be an appropriate choice. In contrast, repeater stations that receive data from many different locations will probably require an omnidirectional antenna. 
    • Consider if a high-gain antenna is needed to overcome the path between two points. Higher-gain antennas are larger and more expensive. 

    To help with antenna selection and site placement, consider renting and using a demo kit to test the pathway quality. Campbell Scientific offers a 900 MHz demo kit for the RF401, RF430, CR206X, and AVW206, as well as a demo kit for the RF450. Contact an application engineer at Campbell Scientific for assistance.