Campbell CDM-VW300 Series, User Manual

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G-1
Appendix G. CRBasic Program Library
The following example programs are compatible with CR3000, CR1000, and
CR800 dataloggers without modification. The programs are available for
download at
www.campbellsci.com/downloads . Look for "CDM-VW300
Example Programs." The programs are named with a .CR3 extension and can be
renamed as .CR1 or .CR8 without modification to run on the CR1000 or CR800
dataloggers. To use programs from this library,
1. Select the desired program and save it to your PC.
2. Open CRBasic Editor .
3. Open the program file just downloaded to edit, if necessary.
4. Send the program to the datalogger using the program Send command in
RTDAQ or LoggerNet .
5. Monitor the operation of the system with the numeric and graphical
monitors available with
RTDAQ or LoggerNet .
G.1 Dynamic Measurements
G.1.1 20 Hz Measurement Example
— One CDM-VW300, Two
Channels
'===20Hz-1Device2Ch_4-25-13.CR3===
'CR3000 datalogger
'CDM-VW300 vibrating-wire analyzer
'Program to read 20 Hz dynamic data from one CDM-VW300 analyzer measuring two channels
'IMPORTANT -- Ensure that the CPI address coded on the following line matches the address
'reported for the attached analyzer in the DevConfig or DVWTool software.
Const CPI_ADDR = 1 '<<<<<<<<<<<<<<SET CPI ADDRESS HERE
Public Freq(2) 'dynamic frequencies
Public Diag(2) As Long 'diagnostic code
Public StaticFreq(2) 'Static (1 Hz output) frequencies
Public Therm(2) 'Thermistor readings
'Standard Deviation of the dynamic readings that occurred during the latest one-second interval
Public DynStdDev(2)
'The following arrays are used to configure the CDM-VW300. Refer to the CDM_VW300Config
'instruction used below
' CH1 CH2
' --- ---
'Set to true (Enabled=1, Disabled=0) only those channels which have sensors connected
Dim Enable(2) As Long = { 1, 1}
'Specify the target/desired resonant amplitude at which the sensor will be maintained
'via excitation, given in volts. This should be in the range 0.010 to 0.001
Dim Max_AMP(2) = { 0.002, 0.002}
'Low Frequency Boundary (sensor frequency should never fall below
'this value regardless of environmental changes)
Dim F_Low(2) = { 300, 300}
'High Frequency Boundary (sensor frequency should never exceed
'this value regardless of environmental changes)
Dim F_High(2) = { 6000, 6000}
'Output Format - Hz vs. Hz^2 :: Value of 0 – measured frequency is given in units of Hz,
'Value of 1 – measured frequency is squared and given in units of Hz^2
Dim OutForm(2) As Long = { 0, 0}
'Multiplier (factor) to be applied to sensor output frequency
Dim Mult(2) = { 1.0, 1.0}
'Offset (shift) to be applied to sensor output frequency
Dim Off(2) = { 0.0, 0.0}
'Steinhart-Hart coefficients [A,B,C] for converting thermistor ohms to
'temperature in Celsius. Specifying zeroes for A,B,C results in a reading in Ohms.
Dim SteinA(2) = { 0.0, 0.0}
Dim SteinB(2) = { 0.0, 0.0}