Campbell Scientific CR510 Basic Datalogger User Manual

Page 158

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SECTION 13. CR510 MEASUREMENTS

13-14

FIGURE 13.4-2. Excitation and Measurement Sequence for 4 Wire Full Bridge

TABLE 13.4-1. Comparison of Bridge Measurement Instructions

Instr. # Circuit

Description

4

DC Half Bridge

The delay parameter

allows the user entered
settling time com-
pensate for capacitance
in long lead lengths. No
polarity reversal. One
single-ended measure-
ment. Measured
voltage output.

5

AC Half Bridge

Rapid reversal of

excitation polarity for
ion depolarization.
One single-ended
measurement at each
excitation polarity.
Ratiometric output.

6

4 Wire

One differential

Full Bridge

measurement at each

excitation polarity.
Ratiometric output.

Instr. # Circuit

Description

7

3 Wire

Compensates for lead

Half Bridge

wire resistance,

assuming resistance is
same in both wires.
Two single-ended
measurements at each
excitation polarity.
Ratiometric output.

8

Differential

Makes a differential

Measurement

measurement without

with Excitation

reversing excitation

polarity. Used for fast
measurements on load
cells, PRTs etc.
Resolution and common
mode rejection worse
than 6 if used with delay
= 0. Measured voltage
output.

9

6 Wire

Compensates for lead

Full Bridge

wire resistance. Two

or 4 Wire

differential measure-

Half Bridge

ments at each

excitation polarity.
Ratiometric output.

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