Campbell CR5000 Specifiche Scaricare il pdf (Pagina 132)

Section 7. Measurement Instructions

7-6

BrHalf3W (Dest, Reps, Range, SEChan, ExChan, MeasPEx, ExmV, RevEx,

SettlingTime, Integ, Mult, Offset)

X = result w/mult = 1,

offset = 0

−

This Instruction is used to determine the ratio of the sensor resistance to a

known resistance using a separate voltage sensing wire from the sensor to

compensate for lead wire resistance.

The measurement sequence is to apply an excitation voltage and make two

voltage measurements on two adjacent single-ended channels: the first on the

reference resistor and the second on the voltage sensing wire from the sensor.

The two measurements are used to calculate the resulting value (multiplier = 1,

offset = 0) that is the ratio of the voltage across the sensor to the voltage across

the reference resistor.

BrHalf4W (Dest, Reps, Range1, Range2, DiffChan, ExChan, MeasPEx,

ExmV, RevEx, RevDiff, SettlingTime, Integ, Mult, Offset)

X = result w/mult = 1,

offset = 0

This Instruction applies an excitation voltage and makes two differential

voltage measurements, then reverses the polarity of the excitation and repeats

the measurements. The measurements are made on sequential channels. The

result is the voltage measured on the second channel (V

) divided by the

voltage measured on the first (V

). The connections are made so that V

is the

voltage drop across the fixed resistor (R

), and V

is the drop across the sensor

). The result with a multiplier of 1 and an offset of 0 is V

/ V

which

equals R

/ R

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Campbell CR5000 Specifiche Pagina 132