Campbell Scientific AVW200-series Vibrating Wire Interfaces User Manual

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AVW200-series 2-Channel Vibrating Wire Spectrum Analyzer Modules

being measured using a multiplexer. The first dimension is

set equal to the number of sensors being measured and the

second dimension is set equal to the number of values

returned for each sensor (5 or 6). For example, to measure 4

sensors with thermistor measurements attached to a

multiplexer, Dest would be declared as Array(4,6). Values

for sensor 1 would be stored in Array(1,1) through

Array(1,6), values for sensor 2 stored in Array (2,1) through

(2,6), etc.

The values returned for each sensor are:

(1) Frequency in Hertz

(2) Amplitude in mV RMS

(3) Signal-to-noise ratio

(4) Noise frequency

(5) Decay ratio

(6) Thermistor in ohms (if measured)

The units and description of these values are provided in

If communication is unsuccessful, NANs are stored.

When using the CRBasic AVW200 instruction, the signal strength

Amplitude in mV rms ( Dest(2) ) has a minimum resolution of

0.0625 (62.5 microvolts). This means that values between 0.01

and 0.06249 mV (10 and 62.49 microvolts) will be given as 0.

Values between 0.0625 and 0.1249 will be given as 0.0625.

Values between 0.125 and 0.18749 will be given as 0.125, and so

forth. With firmware Std.04 and higher, values less than 0.01 will

be shown as NAN, otherwise as 0.

To see amplitudes with higher resolution, use SDI-12

(Section 3.3.1, SDI-12 Communication), Terminal mode

(Section 5.7, Terminal), or the "Troubleshoot" tab in

DevConfig (Section 5.5, Troubleshoot) to examine signal

strength amplitude values.

AVWChan

The AVWChan is the channel on the AVW200 where the

sensor or multiplexer is wired. Valid options are 1 (1V+/-) or

2 (2V+/-).

MuxChan

The MuxChan is the channel on the multiplexer where

measurements should start. Valid options are 1 through 32;

anything outside of this range returns an error. Enter 1 if a

multiplexer is not used.

Reps

The Reps parameter is the number of measurements to be

made on the multiplexer. This parameter does not affect the

AVW200Chan.

NOTE