Module giao diện 8 kênh dây rung Campbell Scientific CDM-VW305

Thương hiệu: Campbell Scientific | Tình trạng: Còn hàng
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CDM-VW305 8-Channel Dynamic Vibrating-Wire Analyzer

Gọi 0904251826 để được trợ giúp

Module giao diện 8 kênh dây rung Campbell Scientific CDM-VW305


The CDM-VW305 is an 8-channel interface between sensors and dataloggers that allows shorter intervals between measurements. This interface uses an excitation mechanism that maintains the vibrating-wire sensor in a continuously vibrating state. The interface measures the resonant frequency of the wire between excitations using the patented vibrating-wire spectral-analysis technolgy (VSPECT™). VSPECT provides very fine measurement resolution and also limits the influence of external noise by discriminating between signal and noise based on frequency content. Because of this technology, the signal can be carried through longer cables, giving flexibility in sensor and datalogger siting.

The CDM-VW305 interfaces with standard vibrating-wire sensors, giving much faster and better measurements without having to purchase new sensors. The analyzer allows high data rates, and multiple CDM-VW305 modules can be connected to one datalogger. The CDM-VW300 is similar to this item, but has 2 channels. U.S. Patent No. 8,671,758.

Benefits and Features

  • Interfaces to standard single-coil vibrating-wire sensors

  • Eight simultaneously sampled channels per module; synchronizable across multiple modules

  • Dynamic measurement rates of 20 to 333 Hz

  • Static measurement at 1 Hz made simultaneously with the dynamic measurement

  • Spectral interpolation approach provides superior noise immunity and measurement resolution compared to time-domain period-averaging approach

  • Excitation method provides frequent low-energy pulses to maintain a continuous resonant vibration in the sensor

  • Thermistor input for each vibrating-wire channel is sampled at 1 Hz

  • Datalogger communications via CPI

  • User-configurable, onboard post-processing of the data including frequency output conversion, temperature conversion, and rainflow histogram collection

Detailed Description

In addition to the dynamic vibrating-wire measurement, the CDM-VW305 makes several auxiliary measurements. A static vibrating-wire measurement is made once each second, along with the dynamic measurements, which provides finer measurement resolution and greater immunity to external noise sources. The CDM-VW305 includes a thermistor input channel paired with each vibrating-wire channel, featuring high-precision 24 bit measurements at a 1 Hz rate. Lastly, a rich set of diagnostic parameters is provided with the vibrating-wire data.

The CDM-VW305 has the capability to simplify post-processing of data by computing common values internally. Vibrating-wire data can be reported as measured frequency or as the frequency squared with a multiplier and offset applied. The thermistor data is reported as resistance or is converted to degrees Celsius using the thermistor’s Steinhart-Hart coefficients. The CDM-VW305 also can internally compile rainflow histograms from the final data and report the values at user-specified intervals.



Electrical specifications are valid over a -25° to +50°C range unless otherwise specified. Non-condensing environment required.

Scan Rates

20, 50, 100 Hz

CPI Baud Rate

Selectable from 25 kbps to 1 Mbps

Input Resistance

5 kΩ

Excitation Voltage Range

0 to ±3 V (6 V peak-to-peak)

Excitation Voltage Resolution

26 mV

Operating Temperature Range

  • -25° to +50°C (standard)

  • -55° to +85°C (extended)

Measurement Frequency Accuracy

±(0.005% of reading + Resolution)

Sustained Input Voltage without Damage

-0.5 to +7.1 V


20.3 x 12.7 x 5.1 cm (8 x 5 x 2 in.)

Measurement Resolution at Sample Rates


Typical values for a 2.5 kHz resonant sensor

1 Hz Sample Rate

0.005 Hz RMS (noise level)

20 Hz Sample Rate

0.008 Hz RMS (noise level)

50 Hz Sample Rate

0.015 Hz RMS (noise level)

100 Hz Sample Rate

0.035 Hz RMS (noise level)

Sensor Resonant Frequency Range

20 Hz Sample Rate

  • 290 Hz (minimum sensor frequency)

  • 6000 Hz (maximum sensor frequency)

50 Hz Sample Rate

  • 290 Hz (minimum sensor frequency)

  • 6000 Hz (maximum sensor frequency)

100 Hz Sample Rate

  • 580 Hz (minimum sensor frequency)

  • 6000 Hz (maximum sensor frequency)


Completion Resistor

4.99 kΩ 0.1%

Excitation Voltage

1.5 V


0.002 Ω RMS (@ 5 kΩ thermistor resistance)


0.15% of reading (Thermistor accuracy and resistance of the wire should be considered as additional errors.)

Measurement Rate

1 Hz

Power Requirements


9.6 to 32 Vdc

Typical Current Drain

190 mA (@ 12 Vdc)



CDM-VW300 Series Dynamic Vibrating-Wire Measurement Modules

Vibrating-Wire Spectral Analysis Technology (VSPECT)


CDM-VW300 Series Dynamic Vibrating-Wire Analyzer System

Technical Papers

Instrumentation for Making High-Precision Dynamic Vibrating-Wire Measurements Using Standard Single-Coil Gages

Designing Physical Network Layouts for the CPI Bus


CDM-VW300 and CDM-VW305 EU Declaration of Conformity

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