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CDM-VW300
User Manual
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Campbell Scientific CDM-VW300 User Manual

CDM-VW300 Series
Dynamic Vibrating-Wire
Analyzers
Revision: 11/13
Campbell Scientific, Inc.
Copyright © 2013

Warranty

Assistance

Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company serves
your country.
To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000. After an application engineer determines the nature of the problem, an RMA number will be issued. Please write this number clearly on the outside of the shipping container. Campbell Scientific’s shipping address is:
CAMPBELL SCIENTIFIC, INC. RMA#_____ 815 West 1800 North Logan, Utah 84321-1784
For all returns, the customer must fill out a “Statement of Product Cleanliness and Decontamination” form and comply with the requirements specified in it. The form is available from our web site at www.campbellsci.com/repair. A completed form must be either emailed to repair@campbellsci.com or faxed to (435) 227-9106. Campbell Scientific is unable to process any returns until we receive this form. If the form is not received within three days of product receipt or is incomplete, the product will be returned to the customer at the customer’s expense. Campbell Scientific reserves the right to refuse service on products that were exposed to contaminants that may cause health or safety concerns for our employees.

Table of Contents

PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections.
1. Introduction.................................................................1
2. Cautionary Statements............................................... 2
3. Initial Inspection .........................................................2
4. Overview......................................................................3
4.1 Channel Allocations .............................................................................3
4.2 Measurement Rates ..............................................................................4
4.3 Integrated Thermistor Measurement ....................................................4
4.4 Laboratory Mode..................................................................................5
4.5 Field Mode ...........................................................................................5
4.6 Data Uses .............................................................................................6
4.6.1 Static Measurements .....................................................................6
4.6.2 Dynamic Measurements................................................................6
4.6.3 Thermistor Measurements.............................................................6
4.6.4 Rainflow Histograms ....................................................................7
4.6.5 System Diagnostics .......................................................................7
5. Specifications .............................................................7
5.1 Features ................................................................................................7
5.2 Specifications .......................................................................................8
6. Installation.................................................................10
6.1 Laboratory-Mode Installation ............................................................11
6.1.1 Laboratory-Mode Installation Equipment...................................11
6.1.2 Laboratory-Mode Installation Procedure ....................................12
6.2 Field-Mode Installation ......................................................................18
6.2.1 Field-Mode Installation Equipment ............................................18
6.2.2 Field-Mode Installation Procedure..............................................18
7. System Operation .....................................................26
7.1 PC Based Tools..................................................................................26
7.1.1 Software and Driver Installation .................................................26
7.1.2 Using DVWTool.........................................................................27
7.1.2.1 Ensure Connection is Active ............................................27
7.1.2.2 DVWTool Settings Editor ................................................28
7.1.2.3 Button and Field Descriptions..........................................28
7.1.3 Using DevConfig ........................................................................29
7.1.3.1 Ensure Connection is Active ............................................29
7.1.3.2 DevConfig Settings Editor ...............................................30
i
Table of Contents
7.2 Using the Datalogger......................................................................... 30
7.3 Using the SC-CPI Interface ............................................................... 31
7.4 Using Power Supplies........................................................................ 31
7.4.1 CDM-VW300 Series Analyzer Power ....................................... 31
7.4.2 Data-Acquisition System Power................................................. 32
7.5 Configuring the CDM-VW300 Analyzer .......................................... 32
7.5.1 Device Name.............................................................................. 34
7.5.2 CPI Bus Speed............................................................................ 34
7.5.3 Operating System Version.......................................................... 35
7.5.4 Operating System Date............................................................... 35
7.5.5 Analyzer Serial Number............................................................. 35
7.5.6 Display Rate ............................................................................... 35
7.5.7 Dynamic Sample Rate................................................................ 35
7.5.8 Device Type ............................................................................... 35
7.5.9 CPI Bus Address ........................................................................ 35
7.5.10 System Options .......................................................................... 35
7.5.11 Channels Enabled....................................................................... 36
7.5.12 Desired Resonant Amplitude...................................................... 36
7.5.13 Minimum- and Maximum Cut-Off Frequencies ........................ 36
7.5.14 Frequency-Output Format .......................................................... 36
7.5.15 Multipliers and Offsets ............................................................... 36
7.5.16 Steinhart-Hart Coefficients......................................................... 36
7.5.17 Rainflow-Histogram Output Configurations .............................. 36
7.6 Sensor Selection ................................................................................ 37
7.6.1 Frequency Considerations.......................................................... 37
7.6.2 Noise Performance ..................................................................... 37
7.7 System Connections .......................................................................... 37
7.7.1 CDM-VW300 to PC Connection ............................................... 38
7.7.2 CDM-VW300 to Sensor Connection.......................................... 38
7.7.3 CDM-VW300 to SC-CPI Connection ........................................ 40
7.7.4 CDM-VW300 to Power Connection .......................................... 42
7.7.5 Earth Ground Connections ......................................................... 44
7.7.6 Communication Connections ..................................................... 44
7.7.6.1 SC-CPI to CPI Bus Connection....................................... 44
7.7.6.2 Datalogger to SC-CPI Connection................................... 44
7.7.7 Maximum Number of Analyzers on a Datalogger ..................... 45
7.8 Operating System .............................................................................. 46
7.9 Power-Up Sequence .......................................................................... 46
7.10 CRBasic Programming ...................................................................... 47
7.10.1 Writing Programs ....................................................................... 47
7.10.2 Sending Programs to the Datalogger.......................................... 48
7.11 System Adjustments .......................................................................... 49
7.11.1 Frequency Range........................................................................ 49
7.12 System Validation ............................................................................. 49
7.12.1 Sensor Validation ....................................................................... 49
7.12.2 Monitoring System Performance................................................ 49
7.12.2.1 Monitoring with DVWTool Software.............................. 52
7.12.2.1.1 Fault Detection...................................................... 52
8. Troubleshooting........................................................53
8.1 Connections ....................................................................................... 53
8.2 Power................................................................................................. 53
8.3 Isolating Components ........................................................................ 53
8.4 Filtering Harmonics........................................................................... 54
8.5 Diagnostic Outputs............................................................................ 54
ii
Table of Contents
8.5.1 Diagnostic Codes (Dynamic) ......................................................54
8.5.1.1 Description of Diagnostic Parameters ..............................55
8.5.1.2 Calculating Low- and High-Frequency Boundaries.........56
8.5.1.3 Using Diagnostic Parameters ...........................................57
8.5.1.4 Decoding the Diagnostic Code.........................................57
8.5.1.4.1 Excitation Strength ................................................57
8.5.1.4.2 Low-Amplitude Warning Flag ..............................57
8.5.1.4.3 High-Amplitude Warning Flag..............................58
8.5.1.4.4 Low-Frequency Warning Flag...............................58
8.5.1.4.5 High-Frequency Warning Flag..............................58
8.5.1.4.6 Interpreting the Diagnostic Code...........................58
8.5.2 Standard Deviation of Dynamic Output......................................59
8.6 Factory Default Reset.........................................................................59
9. Glossary ....................................................................60
10. References and Attributions....................................60
Appendices
Measurement Theory.............................................. A-1
A.
A.1 Dynamic Vibrating-Wire Measurements ........................................ A-1
A.1.1 Dynamic and Static Frequencies.............................................. A-2
B. SC-CPI Datalogger to CPI Interface....................... B-1
B.1 Introduction......................................................................................B-1
B.2 Quickstart.........................................................................................B-1
B.3 Overview..........................................................................................B-1
B.4 Specifications ...................................................................................B-3
C. CDM Devices and CPI Bus..................................... C-1
C.1 CDM Interconnection and Datalogger Connection..........................C-1
C.1.1 Power ........................................................................................C-1
C.1.2 Interconnect Cable ....................................................................C-1
C.1.3 Speed as a Function of Distance ...............................................C-2
C.1.4 CPI Grounding ..........................................................................C-3
C.1.6 Addressing ................................................................................C-3
C.2 Distributed Architecture...................................................................C-3
D. Digits Conversion ................................................... D-1
D.1 Example: Frequency to Digits to Displacement.............................. D-1
E. Calculating Measurement Error............................. E-1
E.1 Example Error Calculation: Geokon Strain Gage ............................ E-1
E.2 Example Error Calculation: DGSI Embedment Strain Gage ...........E-2
E.3 Example Error Calculation: DGSI Spot-Welded Strain Gage..........E-2
E.4 Example Error Calculation: Geokon 4420 Crack Meter .................. E-2
E.5 Example Error Calculation: DGSI Piezometer 52611099................E-3
iii
Table of Contents
F. Thermistor Information........................................... F-1
F.1 Converting Resistance to Temperature.............................................F-1
F.1.1 Resistance Conversion Example – Geokon Sensor................... F-1
F.2 Accuracy and Resolution..................................................................F-1
G. CRBasic Program Library ......................................G-1
G.1 Dynamic Measurements .................................................................. G-1
G.1.1 20 Hz Measurement Example — One CDM-VW300, Two
Channels ............................................................................... G-1
G.1.2 20 Hz Measurement Example — One CDM-VW305, Eight
Channels ............................................................................... G-2
G.1.3 20 Hz Measurement Example — Three CDM-VW305s, 24
Channels ............................................................................... G-4
G.1.4 20 Hz Measurement Example — Six CDM-VW305s, 48
Channels ............................................................................... G-5
G.1.5 50 Hz Measurement Example — One CDM-VW300, Two
Channels ............................................................................... G-8
G.1.6 50 Hz Measurement Example — One CDM-VW305, Eight
Channels ............................................................................... G-9
G.1.7 50 Hz Measurement Example — Three CDM-VW305s, 24
Channels ............................................................................. G-11
G.1.8 50 Hz Measurement Example — One CDM-VW300, Two
Channels, Rainflow Histogram........................................... G-12
G.1.9 50 Hz Measurement Example — One CDM-VW305, Eight
Channels, Rainflow Histogram........................................... G-14
G.1.10 50 Hz Diagnostic Example — One CDM-VW300, Two
Geokon 4000 Sensors with FieldCal() ................................ G-15
G.1.11 50 Hz Measurement Example — One CDM-VW300, Two
Geokon 4000 Sensors with FieldCal() ................................ G-17
G.1.12 50 Hz Measurement Example — One CDM-VW300, Two
Geokon 4000 Sensors with FieldCal() and CardOut() to
CF .......................................................................................G-19
G.1.13 50 Hz Measurement Example — One CDM-VW300, Two
Geokon 4000 Sensors with FieldCal() and TableFile() to
CF .......................................................................................G-21
G.1.14 100 Hz Measurement Example — One CDM-VW300, Two
Channels ............................................................................. G-23
G.1.15 100 Hz Measurement Example — One CDM-VW305,
Eight Channels.................................................................... G-24
G.2 Static Measurements...................................................................... G-25
G.2.1 1 Hz Measurement Example — One CDM-VW300, Two
Channels ............................................................................. G-25
G.2.2 1 Hz Measurement Example — One CDM-VW305, Eight
Channels ............................................................................. G-26
Figures
4-1. Two-channel CDM-VW300 wiring panel........................................... 3
4-2. Eight-channel CDM-VW305 wiring panel.......................................... 4
4-3. Measurement speeds of the AVW200 and CDM-VW300 analyzers .. 4 4-4. Single-coil vibrating-wire sensor including coil and thermistor
outputs.............................................................................................. 5
4-5. Laboratory-mode measurement system diagram................................. 5
4-6. Field-mode data-acquisition system diagram ...................................... 6
iv
Table of Contents
6-1. Laboratory-mode measurement system..............................................11
6-2. 12 Vdc power connection on the CDM-VW300................................12
6-3. USB receptacle on CDM-VW300 and Type-Micro-B connector
of USB cable...................................................................................13
6-4. Sensor connection on a CDM-VW305...............................................16
6-5. Three-wire vibrating-wire sensor connections ...................................16
6-6. Five-wire vibrating-wire sensor connections .....................................16
6-7. Field data-acquisition system.............................................................18
6-8. CPI communications links .................................................................21
6-9. Datalogger to SC-CPI connection ......................................................21
6-10. Connecting the CPI ports of the SC-CPI and CDM-VW300 .............22
6-11. Install CPI bus terminator ..................................................................22
6-12. Power connection ...............................................................................23
6-13. Earth ground connections...................................................................24
7-1. DVWTool Settings Editor and Data Display .....................................28
7-2. DevConfig Settings Editor .................................................................30
7-3. 12 Vdc power transformer for laboratory-mode installation..............31
7-4. USB port on the CDM-VW300..........................................................38
7-5. Three-wire vibrating-wire sensor leads..............................................38
7-6. Three-wire vibrating-wire sensor connection.....................................39
7-7. Five-wire, vibrating-wire sensors leads..............................................39
7-8. Five-wire vibrating-wire sensor connection.......................................40
7-9. SC-CPI and CDM-VW300 CPI ports with RJ45 cable marked
with yellow tape..............................................................................41
7-10. CPI terminator installed .....................................................................41
7-11. Multiple analyzers on a CPI bus ........................................................42
7-12. Installing 12 Vdc transformer on the CDM-VW300 ..........................43
7-13. Daisy-chaining 12 Vdc power input on the CDM-VW300 ................43
7-14. Earth ground connections...................................................................44
7-15. CR3000 and SC-CPI connections ......................................................45
7-16. LoggerNet connect screens showing frequencies from
CDM-VW300 .................................................................................50
7-17. RTDAQ screens showing frequencies in Public table.......................51
7-18. Dynamic Vibrating-Wire Tool Box Fault Indicators .........................52
A-1. Timing of dynamic vibrating-wire measurements .......................... A-2
B-1. Connection to the SC-CPI in DevConfig .........................................B-2
C-1. CPI pin assignments.........................................................................C-2
C-2. Long cable lengths of a distributed CPI bus.....................................C-4
D-1. Geokon Calibration Report of a Sensor without a Thermistor........ D-2
F-1. Temperature measurement error at three temperatures as a
function of lead length. Wire is 22 AWG with 16 ohms per
1000 feet. ...................................................................................... F-2
F-2. Temperature measurement error on a 1000 foot lead. Wire is
22 AWG with 16 ohms per 1000 feet........................................... F-3
F-3. Temperature measurement error on a 3000 foot lead. Wire is
22 AWG with 16 ohms per 1000 feet........................................... F-3
F-4. Temperature measurement error on a 5000 foot Lead. Wire is
22 AWG with 16 ohms per 1000 feet........................................... F-4
Tables
5-1. CDM-VW300 / Datalogger Compatibility...........................................8
5-2. CDM-VW300/305 Sensor Resonant Frequency Range (Hz)...............9
5-3. CDM-VW300/305 Effective Frequency Measurement Resolution4....9
6-1. CDM-VW300 Status LED States.......................................................17
6-2. DVWTool and CRBasic Settings.......................................................19
v
Table of Contents
7-1. Summary of CDM-VW300 Configuration Settings.......................... 33
7-2. Relationship of Sample Rate and Sensor Frequency......................... 37
7-3. Number of Analyzers and Channels Supported by a Datalogger
Writing to CF Card ........................................................................ 45
7-4. CDM-VW300 Scan Rate / Datalogger Scan() Interval Pairings ....... 47
7-5. CDM-VW300 Channel-Status LED States ....................................... 49
8-1. Scan Rate and Boundary Resolution ................................................. 56
8-2. Diagnostic Code Ranges.................................................................... 58
C-1. Maximum Potential Speed as a Function of Distance1.................... C-2
vi
CDM-VW300 Series Dynamic Vibrating­Wire Analyzers
Configuring a dynamic vibrating-wire measurement system requires an integrated system-wide approach. Please review this manual before connecting hardware together or to the PC. The ResourceDVD, which ships free of charge with most Campbell Scientific instrumentation orders, contains the following tools that will help you configure a dynamic vibrating-wire analyzer system:
• A copy of this manual
• DVWTool Dynamic Vibrating-Wire Toolbox software for CDM-
VW300 support
• DevConfig Device Configuration Utility software
• Required datalogger operating systems
Other support information and downloads are available at
www.campbellsci.com/cdm-vw300-support.

1. Introduction

Vibrating-wire sensors are commonly used in geotechnical or structural monitoring applications to measure strain, load, tilt, inclination, temperature, pressure, extension, and crack movement. CDM-VW300 Series Dynamic Vibrating-Wire Analyzers facilitate sub-second measurement of vibrating-wire sensors. These analyzers perform advanced excitation, spectral analysis, and digital signal processing to obtain high-accuracy measurements. Data are stored on a Campbell Scientific datalogger, which is normally used to control the system in field installations.
The CDM-VW300 has two modes of operation:
• Laboratory mode
o Manual operation o Does not require a datalogger o Requires a PC o Used in short-term evaluation o Real-time data and metadata are monitored with PC
• Field mode
o Automated operation o Requires a datalogger o PC used only for setup and collection of data from datalogger o Used in long-term monitoring applications o Time-series data and metadata stored in datalogger memory
Two analyzer models are available in the CDM-VW300 series:
• CDM-VW300 (two channels)
• CDM-VW305 (eight channels)
1
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
See TABLE 5-1, CDM / Datalogger Compatibility, in Section 5, Specifications, for datalogger compatibility information.
Other than a few clearly noted exceptions, any discussion in this manual of the CDM-VW300 also applies to the CDM-VW305.
Before using the CDM-VW300, please study
• Section 2, Cautionary Statements
• Section 3, Initial Inspection
Detailed installation, operation, and troubleshooting information can be found in the remaining sections.

2. Cautionary Statements

• CAUTION — Do not connect power to the system until it is completely
assembled.
• IMPORTANT — Do not connect the CDM-VW300 analyzer or SC-CPI
interface to a PC until AFTER installing DVWTool or DevConfig on the PC. Consult Section 7.1.1, Software and Driver Installation, for more information.
• All references to DVWTool mean Dynamic Vibrating-Wire Tool Box
software version 1.0 or later. DVWTool is available on current versions of the ResourceDVD that ships with CDM-VW300 series analyzers. All references to DevConfig mean Device Configuration Utility software version 2.04 or later. DevConfig is available from the these three sources:

3. Initial Inspection

• CDM-VW300 series analyzers ship with,
o 1 each pn 29389 CDM Parts Kit o 1 each ResourceDVD, which contains DVWTool and current
• Upon receipt of the CDM-VW300, inspect the packaging and contents for
damage. File damage claims with the shipping company.
• Thoroughly check all packaging material for product that may be
concealed inside it. Check model and part numbers, and product descriptions against the shipping documents. Model or part numbers are found on each product. Cable numbers are normally found at the end of the cable that connects to the measurement device. Check that expected cable lengths were received. Contact Campbell Scientific immediately concerning any discrepancies.
o ResourceDVD shipped with CDM-VW300 series analyzers
o www.campbellsci.com/downloads (no charge)
o Installations of LoggerNet, PC400, PC200W, or RTDAQ
software. Check the Help | About screen in DevConfig for the version number.
DevConfig software.
2

4. Overview

4.1 Channel Allocations

CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Single-coil vibrating-wire sensors are preferred in many applications because they are stabile, accurate, and durable. CDM-VW300 Series Dynamic Vibrating-Wire Analyzers make accurate high-speed measurements of the resonant frequencies of these sensors at sub-second intervals using advanced excitation and signal processing techniques, including spectral analysis. Resonant frequency data are passed with diagnostics to a Campbell Scientific datalogger. Applications include characterization of events that require rapid measurements and data storage, and measurement of sensor signals too weak to be measured with other instrumentation. See Appendix A, Measurement Theory, for more information.
Dynamic vibrating-wire measurements require a complete system of instrumentation. This manual focuses on the use of CDM-VW300 series analyzers, but it also gives basic guidance on system configuration.
As illustrated in FIGURE 4-1, the CDM-VW300 simultaneously measures two vibrating-wire sensors. FIGURE 4-2 shows that the CDM-VW305 has the capacity to measure eight sensors. When more than eight channels are needed, multiple devices are attached to the same datalogger through the CPI bus. See Section 7.7.7, Maximum Number of Analyzers on a Datalogger, and Appendix C, CDM Devices and CPI Bus, for details on connecting multiple analyzers to a CPI bus.
FIGURE 4-1. Two-channel CDM-VW300 wiring panel
3
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
FIGURE 4-2. Eight-channel CDM-VW305 wiring panel

4.2 Measurement Rates

CDM-VW300 analyzers use patented techniques to measure sensors at rates from 1 to 333.3 Hz. Systems that exclusively require rates slower than 1 Hz should use a Campbell Scientific AVW200-Series Vibrating-Wire Spectrum Analyzer.
4
FIGURE 4-3. Measurement speeds of the AVW200 and CDM-VW300
analyzers

4.3 Integrated Thermistor Measurement

Many vibrating-wire sensors include an integrated thermistor to allow for temperature compensation of the vibrating-wire measurement. The CDM­VW300 supports thermistor measurements and the associated temperature compensation required in some applications.
Vibrating Wire
Thermistor
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Stainless Steel Housing
4-Conductor Cable
Two Thermistor
Outputs
Diaphragm
Filter
Plucking and Pickup Coils
FIGURE 4-4. Single-coil vibrating-wire sensor including coil and
thermistor outputs

4.4 Laboratory Mode

Laboratory mode allows for examination and validation of specific measurements types without a datalogger, such as might occur before field deployment. As shown in FIGURE 4-5, a connection is made from the CDM­VW300 to a personal computer using a USB cable. Campbell Scientific DVWTool software on the PC enables observation of sensor outputs and configuration of the CDM-VW300 to measure sensors. Specific procedures can be found in Section 6.1.2, Laboratory-Mode Installation Procedure.
Vibrating-Wire
Sensors
CDM-
VW300
Two Coil Outputs
Internal Bulkhead Seal
PC
DVWTool

4.5 Field Mode

FIGURE 4-5. Laboratory-mode measurement system diagram
Field mode is used for long-term measurement and data acquisition. As shown in FIGURE 4-6, a connection is made from the CDM-VW300 to a Campbell Scientific datalogger through the SC-CPI interface. A Campbell Scientific datalogger with a customized CRBasic program configures, controls, and collects data from the CDM-VW300. Specific installation procedures are found in Section 6.2.2, Field-Mode Installation Procedure.
5
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Vibrating-Wire
Sensors
CDM-
VW300
FIGURE 4-6. Field-mode data-acquisition system diagram

4.6 Data Uses

Users should consult authoritative sources concerning the use of vibrating-wire data in structural analysis applications. Following is a short introduction to the use of data made available by CDM-VW300 series analyzers.

4.6.1 Static Measurements

Each sensor is measured for a static frequency once per second. The static frequency is used to obtain a result with finer spectral bin resolution than that which can be achieved at the dynamic measurement rates. This measurement can be helpful in detecting the rare case, for example, in which a noise frequency very near the resonant frequency affects dynamic sampling measurements.
SC-CPI
CR3000
Datalogger
PC
LoggerNet

4.6.2 Dynamic Measurements

Each analyzer can be configured in a 20, 50, 100, 200, or 333.3 Hz sampling mode. By capturing multiple readings each second from a vibrating-wire sensor, rapid changes or events can be captured and evaluated. Due to the Nyquist sampling theorem, only responses equal to or less than half of the sampling frequency can be detected and characterized. Event-based data capture techniques programmed into the controlling datalogger can be helpful to ensure useful data are captured under the right event conditions. In this way, storage and retrieval of less-useful data are avoided.

4.6.3 Thermistor Measurements

Each vibrating-wire sensor input channel has inputs for the thermistor that is usually built into a vibrating-wire sensor. The temperature measurement is normally used to correct the frequency measurement for temperature changes. A 24-bit measurement circuit ensures high-accuracy resistance measurements, which are converted to temperature. Guidance about the impact of temperature on the vibrating wire is usually provided by the manufacturer in documentation provided with each individual sensor. Contact the sensor manufacturer if more information is required.
6

4.6.4 Rainflow Histograms

Rainflow histograms are 3-D representations of the rainflow counting algorithm of Matsuiski and Endo (1968). Rainflow histograms can be used to monitor fatigue levels of structures under stress, such as components of a large­scale transportation bridge. The histograms are calculated by the CDM­VW300 analyzer to ease the processing burden required of the controlling datalogger.
CRBasic Help topic for the Rainflow() instruction has more information about rainflow histograms.

4.6.5 System Diagnostics

Several diagnostic values will help you scrutinize basic CDM-VW300 measurements. Excitation level and low / high frequency or amplitude warnings are provided for each dynamic measurement. A standard deviation is provided once each second.
Excitation level is bounded by setting the amplitude at which the wire in the sensor is to be maintained. That figure is reported so that excitation levels can be monitored. If the analyzer-sensor system experiences a low amplitude, high amplitude, low-frequency, or high frequency condition, that information is also provided.
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Once each second, a standard deviation of a dynamic measurement is provided. Unexplained changes in the standard deviation from baseline levels may indicate noise or other interference.

5. Specifications

5.1 Features

• Measurement of standard, single-coil circuit, vibrating-wire sensors
• Dynamic-sampling rates of 20 to 333.3 Hz
• On-board frequency-output conversion
• Two (CDM-VW300) or eight (CDM-VW305), simultaneously-sampled
• Time synchronization of multiple modules using one datalogger
• Thermistor input for each vibrating-wire channel measured at 1 Hz
• On-board temperature conversion
• Rainflow-histogram compilation
• Superior noise immunity and effective measurement resolution (precision)
• Continuous resonant vibration in the sensor
channels per module
• Spectral analysis method protected under U.S. patent no. 7,779,690. An
additional U.S. patent that relates to the dynamic vibrating-wire measurement technique is pending.
7
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers

5.2 Specifications

Electrical specifications are valid from –25 to 50 °C unless otherwise specified. Non-condensing environment required. Specifications are subject to change.
Compatibility:
TABLE 5-1. CDM-VW300 / Datalogger Compatibility
Maximum CDM-
VW305 Analyzers
Datalogger
Connect with
SC-CPI
1
Module
Maximum
Measurement
Rate (Hz)
at Max Rate /
Maximum
Channels
CR3000 * 1002 1/8
– – 50 3/24
– – 20 6/48
CR800 / CR1000
* 50
1/8
– – 20 4/32
Frequency measurement:
A vibrating-wire circuit is excited and measured through the same coil connection. Sinusoidal excitation persists for a few cycles of the wire oscillation. The wire is maintained in a continuously vibrating state. Excitation voltage varies automatically to maintain the desired return signal strength.
Dynamic measurement
20, 50, 100, 200
3
, and 333.33 Hz
rates:
8
Accuracy:
Input resistance:
Excitation voltage
Range:
Resolution:
±(0.005% of reading + effective measurement resolution)
5 k
0 to ±3 V (6 V peak-to-peak)
26 mV
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Sensor resonant frequency
range:
Sensor Resonant Frequency Range (Hz)
TABLE 5-2. CDM-VW300/305
Sample Rate
20 290 6000
50 290 6000
100 580 6000
2003 1150 6000
333.33 2300 6000
Effective resolution (precision):
TABLE 5-3. CDM-VW300/305
Effective Frequency Measurement Resolution
Sample Rate (Hz) Noise Level (Hz RMS)5
1 0.005
20 0.008
50 0.015
100 0.035
2003 0.11
333.33 0.45
Minimum Sensor
Frequency
Maximum Sensor
Frequency
4
Sustained input voltage without
damage:
Temperature measurement:
Accuracy:
Resolution:
Bridge resistor:
Excitation voltage:
Measurement rate:
–0.5 to 7.1 V
Temperature measurement is available for sensors so equipped. Excitation and half-bridge measurement circuits are integrated into the CDM-VW300 and CDM­VW305 analyzers.
6
0.15% of reading
0.002  RMS @ 5 k thermistor resistance
4.99 k 0.1%
1.5 V
1 Hz
9
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Operating temperature
Standard:
Extended:
Power requirement
Voltage:
Typical current drain
CDM-VW300:
CDM-VW305:
Output
CPI:
USB:
–25° to 50°C
–55° to 85°C
9.6 to 32 Vdc
115 mA @ 12 Vdc
190 mA @ 12 Vdc
Connects to datalogger. Baud rate selectable from 50 kbps to 1 Mbps. Cable length varies depending on baud rate, number of nodes, cable quality, and noise environment. 2500 ft maximum.
Connects to PC. USB 2.0 full speed. Provided for configuration, updates, and communication with DVWTool software. The USB port does not support collection of time-series data.

6. Installation

Weight:
Dimensions:
Mounting:
< 1 kg, < 2 lb
20.3 x 12.7 x 5.1 cm (8 x 5 x 2 in)
One-inch grid. Optional DIN rail mounting is available using Campbell Scientific pn 29388.
1
SC-CPI module connects to terminals C1, C2, C3 (not SDM-C1, SDM-C2, SDM-C3).
2
CR3000 is the recommended datalogger.
3
These rates available only on PC with fast processor using USB cable in lab mode.
4
The effective resolution (precision) of the output is limited by noise and varies with the sample
rate.
5
Typical values for a 2.5 kHz resonant sensor.
6
Thermistor accuracy and resistance of the wire should be considered as additional errors.
The CDM-VW300 system is designed for use with a PC or as part of a field data-acquisition system using a Campbell Scientific CR3000 datalogger. When sensors are sampled at slower rates equal to or less than 50 Hz, a CR1000 or CR800 datalogger can be used.
Pre-configure and test the system before taking it to the field. Issues that are unresolved before placing instrumentation in the field will usually be more
10
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
difficult to resolve. Data-acquisition systems, from the sensors to the telecommunications equipment, are complex. Campbell Scientific equipment and software are among the best available, but the integration process can be demanding and involves trial and error; contingencies should be developed to address possible problems. Do the bulk of the integration work in a comfortable and dry location that has a communications link with Campbell Scientific during regular business hours. If you are experienced with field deployments, set aside at least a full day for pre-configuration work. Otherwise, set aside three to seven days for system development before travelling to the field.

6.1 Laboratory-Mode Installation

IMPORTANT — Do not connect the CDM-VW300 analyzer or SC-CPI interface to a PC until AFTER installing DVWTool 1.0 or later or DevConfig
2.04 or later. Consult Section 7.1.1, Software and Driver Installation, for more information.
Laboratory mode allows for easy examination and validation of measurements. To ensure a successful field deployment, perform this procedure before stepping through the field-mode installation procedure of Section 6.2, Field- Mode Installation.
As illustrated in the following figure, a connection is made directly between the CDM-VW300 and a PC via USB cable. No datalogger is required. DVWTool support software is used to configure, communicate with, and obtain sensor readings from the CDM-VW300.
Vibrating-Wire
Sensors
CDM-
VW300
FIGURE 6-1. Laboratory-mode measurement system

6.1.1 Laboratory-Mode Installation Equipment

The following equipment is used in a laboratory-mode installation:
• Vibrating-wire sensors
• CDM-VW300 measurement module
• PC
• DVWTool software
PC
DVWTool
11
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
r
p

6.1.2 Laboratory-Mode Installation Procedure .1.2 Laboratory-Mode Installation Procedure

The following procedure sets up the measurement system in laboratory mode: The following procedure sets up the measurement system in laboratory mode:
1. Install DVWTool software on the PC. Do this before connecting the CDM-
1. Install DVWTool software on the PC. Do this before connecting the CDM-
VW300 to the PC. DVWTool installation automatically installs drivers for
VW300 to the PC. DVWTool installation automatically installs drivers for the CDM-VW300 USB connection.
the CDM-VW300 USB connection.
Reference Section 7.1.1, Software and Driver Installation.
Reference Section 7.1.1, Software and Driver Installation.
2. Connect 12 Vdc power to the CDM-VW300 as shown in FIGURE 6-2.
2. Connect 12 Vdc power to the CDM-VW300 as shown in FIGURE 6-2.
Reference Section 7.4, Using Power Supplies.
Reference Section 7.4, Using Power Supplies.
Campbell Scientific pn 29796, a 24 Vdc, 1670 mA wall charger, is
Campbell Scientific pn 29796, a 24 Vdc, 1670 mA wall charger, is recommended.
recommended.
Insert small screwdriver
en gates.
to o
Leads from pn 13947 transforme
FIGURE 6-2. 12 Vdc power connection on the CDM-VW300
3. Connect a type-A male to type-micro-B male USB cable (Campbell
Scientific pn 27555, supplied with the analyzer) between the CDM­VW300 and the PC as shown in FIGURE 6-3.
Reference Section 7.7.1, CDM-VW300 to PC Connection.
12
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
FIGURE 6-3. USB receptacle on CDM-VW300 and Type-Micro-B
connector of USB cable
With the driver installed (step 1) and the power connected and live (step
2), connecting the USB cable will start an automatic process that creates a new communication (COM) port for the CDM-VW300 on the PC. Watch the Windows® system tray to see that the PC completes the process. Once complete, a new port will appear as an available communication port in DVWTool.
4. Test to see that DVWTool can access the USB connection.
Reference Section 7.1.2, Using DVWTool.
Run DVWTool. Select CDM-VW300 from the Com Port drop-down list as indicated in the following figure.
13
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
NOTE
If COM port CDM-VW300 does not appear, there is a problem with the installation of the device driver or the creation of the COM port. See Section 7.1.1, Software and Driver Installation, for remedial steps.
Press Connect in the lower left of the DVWTool window. If DVWTool
connects with the CDM-VW300, the channel list on the DVWTool interface becomes available and the button at lower left reads Disconnect as shown in the following figure.
Notice that the fields Device Type, Serial Number, Device Name, and CPI address are active and populated in the lower portion of the DVWTool window. Otherwise, the channel list remains dimmed and the notice Not connected... No data available is displayed at the right of the channel list, as shown in the following figure.
14
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
5. Check the operating system version of the CDM-VW300.
Reference Section 7.8, Operating System.
Operating systems are occasionally updated. To ensure the CDM-VW300 has the latest, search through www.campbellsci.com/downloads for the most recent release. Compare the version information on the website with the version shown in the DVWTool Help | About screen, which is sampled in the following figure.
6. If DVWTool is running, click Disconnect. Remove the 12 Vdc power
from the CDM-VW300.
7. Connect the vibrating-wire sensors to the CDM-VW300 as shown in the
following figures.
Reference Section 7.7.2, CDM-VW300 to Sensor Connection.
15
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
FIGURE 6-4. Sensor connection on a CDM-VW305
Coil Coil Ground
VW
VW
T
T
CDM-VW300
FIGURE 6-5. Three-wire vibrating-wire sensor connections
Coil Coil Ground
Thermistor Thermistor
VW
VW
T
T
1
1
16
CDM-VW300
FIGURE 6-6. Five-wire vibrating-wire sensor connections
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
8. Reconnect 12 Vdc power to the CDM-VW300.
9. Confirm sensor operation.
Reference Section 7.12.1, Sensor Validation.
Two status LED lights are provided on the CDM-VW300 for each sensor connection. Eight are provided on the CDM-VW305. The following table lists LED functions and interpretations:
TABLE 6-1. CDM-VW300 Status LED States
Green or red flash at three-second
Channel is activated.
interval
Green flash Response received from sensor.
Red flash Diagnostic flags indicate there may
be a problem.
No flash, unlit Channel is not activated.
10. Ensure that frequency readings can be obtained from the sensors.
Reference Section 7.12.2.1, Monitoring with DVWTool Software.
Click Connect on the DVWTool window. Check the box associated with each channel to which a sensor is connected. If all sensor systems are operational, the DVWTool main window will appear much as it does in the following figure:
a. Frequency reading of each sensor will correspond to the
frequency range specified by the sensor manufacturer.
b. No faults are indicated. If faults are indicated (Diagnostic Bits
does not equal 0x00, measurement results are in red type, or cells
17
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
are shaded red), consult Section 7.12.2.1, Monitoring with DVWTool Software, for troubleshooting help.

6.2 Field-Mode Installation

IMPORTANT — Do not connect the CDM-VW300 analyzer or SC-CPI interface to a PC until AFTER installing DVWTool 1.0 or later or DevConfig
2.04 or later. Consult Section 7.1.1, Software and Driver Installation, for more information.
A simple field-mode configuration, using one CDM-VW300, is covered in this section. Additional details concerning field-mode configuration and daisy­chaining power and RJ45 connections are discussed in Section 7, System Operation. Capacity of the power supply is a critical element of field installations. Most field-mode installations will require continuous ac power or large solar panels and batteries.

6.2.1 Field-Mode Installation Equipment

The following components are used in a field-mode installation:
• Vibrating-wire sensors
• CDM-VW300 measurement modules
• SC-CPI interface
• Datalogger
• Datalogger power supply
• Personal computer (PC)
• DVWTool analyzer software
• Datalogger support software (LoggerNet, PC400, or RTDAQ)

6.2.2 Field-Mode Installation Procedure

FIGURE 6-7 illustrates the final form of a simplified field-mode installation. With reference to this figure, work through the following procedure. Reference Section 7.7, System Connections, for more information.
Vibrating-Wire
Sensors
CDM-
VW300
12V G
RJ-45 to
RJ-45
FIGURE 6-7. Field data-acquisition system
SC-CPI
12 Vdc and G
Connection
pn 29526
Cable
C1 C2 C3
12V
G
C1 C2 C3
12V
G
Power In
G 12V
CR3000
Datalogger
G 12V
PC
LoggerNet
12 Vdc Ground
Power Supply
18
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Procedure:
1. Install DVWTool before connecting the SC-CPI or CDM-VW300 to the
PC. Reference Section 7.1.1, Software and Driver Installation.
2. Before proceeding, follow the procedure outlined in Section 6.1,
Laboratory-Mode Installation for all sensors connected to the CDM­VW300. Record settings determined in DVWTool for later use in the CRBasic program. The following work sheet (TABLE 6-2) lists DVWTool settings and corresponding CRBasic instruction settings, and provides a place to record settings for one sensor. Copy and fill in this worksheet for each sensor to be connected.
TABLE 6-2. DVWTool and CRBasic Settings
Corresponding CRBasic
Instructions and
DVWTool Setting
Device Name No corresponding setting
Parameters Setting
Scan Rate1 Interval
No corresponding setting
No corresponding setting
No corresponding setting
Device Type (auto-detected) DeviceType
CPI Address CPIAddress
No corresponding setting
Channel X Enable check box
Resonant Amplitude (V) ResonAmp
Minimum Frequency (Hz) LowFreq
Maximum Frequency (Hz) HighFreq
Output Format (Hz or Hz2)
Multiplier Mult
Offset Offset
Steinhart-Hart Thermistor Coeff A
Scan()
1
Units = msec
Buffer = 500
Count = 0
CDM_VW300Config()
SysOptions
ChanEnable
ChanOptions
SteinA
Steinhart-Hart Thermistor Coeff B
Steinhart-Hart Thermistor Coeff C
Rainflow | Number of Mean Bins
SteinB
SteinC
RF_MeanBins
19
CDM-VW300 Series Dynamic Vibrating-Wire Analyzers
Rainflow | Number of Amp Bins
Rainflow | Low Limit
Rainflow | High Limit
Rainflow | Minimum Change
Rainflow | Rainflow Form |
RF_AmpBins
RF_LowLim
RF_HighLim
RF_Hyst
RF_Form
A
reset list
Rainflow | Rainflow Form |
B
total list
Rainflow | Rainflow Form |
C
form list
1
Scan rate is automatically set based on the datalogger CRBasic Scan() instruction Interval parameter. Set the Interval parameter such that the desired CDM-VW300 scan rate is achieved. Relationship between Scan Rate and Interval is:
CRBasic Scan() instruction Interval = (1 / DVWTool Scan Rate) * 1000
3. When the laboratory-mode installation has been performed on all sensors,
click Disconnect in the DVWTool window. Disconnect or turn off power to the CDM-VW300.
4. Assemble the datalogger and power supply using FIGURE 6-7, Field data-
acquisition system, as a guide. Do not turn power on until the system is completely assembled.
5. A reliable data-acquisition system requires a reliable power supply. CDM-
VW300 analyzers consume more power than do many Campbell Scientific products, so the power supplies often used with other data-acquisition systems may not be adequate. Consult Section 7.4, Using Power Supplies, for sizing guidance. For large systems, consult with a Campbell Scientific application engineer.
6. The following figure illustrates the connections between the datalogger,
SC-CPI interface, and CDM-VW300. With this figure as a reference, work through the following procedure.
20
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