Specifications

Section 7. Measurement Instructions
Parameter
& Data Type
Enter
SEChan
The SEChan argument is the number of the single-ended channel on which to
make the first measurement. If the Reps parameter is greater than 1, the
additional measurements will be made on sequential channels. If the SEChan
number is entered as a negative value, all Reps will be performed on the same
channel.
ExChan
The ExChan argument is used to specify the excitation channel to use for the
first measurement. If the Reps parameter is greater than 1, the excitation channel
used for subsequent measurements will be incremented with each measurement.
An alphanumeric or numeric code can be entered:
Alphanumeric Numeric Description
VX1 1 Excitation channel 1
VX2 2 Excitation channel 2
VX3 3 Excitation channel 3
VX4 4 Excitation channel 4
StartFreq
The StartFreq parameter is the frequency, in Hertz, at which to start the
excitation. StartFreq must be greater than 20 Hz.
EndFreq
The EndFreq parameter is the frequency, in Hertz, at which to end the excitation.
EndFreq must be less than 5000 Hz.
TSweep
TSweep is the duration, in milliseconds, of the frequency sweep.
Steps
Steps is the number of step changes in frequency to sweep from the start
frequency (StartFreq) to the end frequency (EndFreq). If -1 is entered for the
Steps parameter, the datalogger will calculate and use the maximum number of
Steps allowed for the selected StartFreq, StopFreq, and TSweep parameter
values. This results in the finest possible resolution in Step size.
DelMeas
The DelMeas parameter is used to specify the number of microseconds to delay
before measuring the return signal after the frequency sweep is completed.
NumCycles
NumCycles is the number of cycles to measure.
DelReps
The DelReps parameter is used to specify the number of microseconds to delay
between each measurement repetition.
Mult, Offset
The Mult and Offset parameters are each a constant, variable, array, or
expression by which to scale the results of the measurement. With a multiplier
(mult) of 1 and an offset of 0, the output is 1/T
2
, where T is the period of the
measured signal in milliseconds.
For additional information on the sweep frequency operation for the
VibratingWire instruction, refer to Sweep Frequency Operation in the CRBasic
Help file.
WriteIO (Mask, Source)
WriteIO is used to set the status of selected control I/O channels (ports) on the
CR3000. (See Also PortSet.) There are 8 ports. The status of these ports is
considered to be a binary number with a high port (+5 V) signifying 1 and a
low port (0 V) signifying 0. For example, if ports 1 and 3 are high and the rest
low, the binary representation is 00000101, or 5 decimal. The source value is
interpreted as a binary number and the ports set accordingly. The mask
parameter is used to select which of the ports to set, it too is a binary
representation of the ports, a 1 means set the port according to the source, a 0
means do not change the status of the port. CRBasic allows the entry of
numbers in binary format by preceding the number with "&B". For example if
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