Campbell CS110 Instruction Manual Download

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Instruction Manual

The CR1000 differential voltage measurement (

VoltDiff

) instruction is given as

follows:

VoltDiff(

Dest,Reps,Range,DiffChan,RevDiff,Settling Time,Integ,Mult,Offset

)

where

Dest

is the destination variable of the result.

Reps

is the number of times to

repeat a given measurement on successive channels,

Range

is one of

5000 mV,

2500 mV,

250 mV,

25 m,

7.5 mV, or

2.5 mV input voltage ranges available

on the CR1000.

DiffChan

is the appropriate differential input channel (1 – 8).

RevDiff

is a true or false parameter to determine whether or not to perform two

successive differential measurements with reversed input polarity, in order to
reduce low-frequency measurement errors.

Settling Time

is a parameter allowing

extra input settling time for “slow” settling sensors.

Integ

is a parameter

indicating the length of time to perform an analogue integration during the
measurement, with options of 250

s, _50Hz and _60Hz. Integration times for

_50Hz and _60Hz are 20 ms and 16.67 ms, respectively for cancellation of
unwanted 50 Hz and 60 Hz noise.

Mult

provides for scaling within the

measurement instruction, while

Offset

provides for the incorporation of offsets.

Single-ended voltage measurements are referenced to ground, rather than the low
side of a differential input. The

VoltSE

single-ended measurement instruction is

quite similar to the

VoltDiff

instruction and is given as follows:

VoltSe (

Dest,Reps,Range,SEChan,MeasOff,Settling Time,Integ,Mult,Offset

)

An internal ground reference is utilized in single-ended measurements. Single-
ended offset errors are reduced in single-ended measurements by measuring the
voltage on the internal ground reference. The

MeasOff

parameter in the

VoltSe

instruction determines if this internal ground reference is measured at the
beginning of every

VoltSe

instruction (

MeasOff

= True) or whether a single-

ended offset voltage measure is performed as part of an on-going instrument self-
calibration routine occurring in background (

MeasOff

= False).

Another general purpose voltage measurement instruction is the

BrHalf

instruction, which provides voltage excitation for a simple resistive divider (half
of a 4-element Wheatstone bridge), and then measures the resulting voltage.

BrHalf

instruction follows:

BrHalf (

Dest,Reps,Range,SEChan,ExChan,MeasPEx,ExmV,RevEx,Settling

Time,Integ,Mult,Offset

)

Most parameters of the

BrHalf

instruction are common to the

VoltDiff

and

VoltSE

instructions, and so only the differences will be discussed. The

ExChan

parameter determines which one of the three CR1000 voltage excitation outputs
are used to excite the half-bridge.

MeasPEx

determines how many successive

channels are excited by the same excitation channel in successive

Reps

ExmV

determines the excitation voltage which can range from –2500 mV to +2500 mV.

RevEx

is a true/false parameter and if true then the polarity of the excitation is

reversed during the measurement and a second measurement taken. Like input
reversal on differential measurements, excitation reversal is an error cancelling
technique for reducing low-frequency measurement errors such as offset voltages.

The

Battery

instruction is used to measure the input voltage of the power supply

to the CS110 and follows:

Battery (

Dest

)

The

PanelTemp

instruction is used to measure the temperature of a thermistor

located within the CS110 case and follows: