Campbell Scientific CR10 CR10 Measurement and Control - Page 129

2

2

2

2

2

4

4

FP

FP

01:

02:

03:

o4:

05:

06:

07:

08:

09:

2

2

2

2

4

4

4

FP

FP

01:

02..

03:

05:

06:

07:

08:

09:

is

specified,

the

inputs for the differential

measurement

are

not switched for a second

integration

as

is normally the

case.

With the

0

delay,

Instruction 8

does

not have as good

resolution or

common mode

rejection

as other

differential measurements.

lt does provide a

very

rapid means

of

making bridge

measurements..

This

instruction does

not

reverse

excitation.

A

1

before

the

excitation

channel

number (1X) causes the channel to be

incremented

with each

repetition.

PARAM.

DATA

NUMBER

TYPE

DESCRIPTION

Repetitions

Range

code

(Table 9-1)

Differential channel

number for

first

measurement

Excitation channel

number

Delay (0.01s)

Excitation voltage

(millivolts)

lnput

location number

for

first measurement

Multiplier

Offset

Input locations

altered:

1

per measurement

***

9

FULL

BRIDGE

WITH EXCITATION

***

COMPENSATION

FUNCTION

This

instruction is used to apply an excitation

voltage and make

two differentialvoltage

measurements. The

measurements

are

made

with both positive and negative excitation

voltage.

The

measurements

are

made on

sequentialchannels.

The

result

is

the voltage

measured

on

the

second

channel (Vr)

divided

by the

voltage

measured

on

the

first

(V1).

lf

V.'

is measured on the 2.5

V

range (code 5,15, 25

or

35

in Parameter 2), then

the

result

is

1000

times

V2A/1. A

1

before the excitation channel

number

(1

X) causes

the

channel

to

be

incremented with each repetition.

When

used as

a 6

wire

full

bridge

(Figure

13.5-

1),

the

connections are

made so that

V1 is

the

measurement

of

the

voltage drop

across the full

bridge, and

V2 is

the

measurement of

the

bridge

output.

Because the excitation voltage for

a

full

bridge measurement is usually

in

the

2.5 V

range, the output is usually 1000

V2A/1

or

millivolts output per volt excitation.

SECTION

9.

INPUT/OUTPUT

INSTRUCTIONS

When

used

to

measure a

4

wire

half bridge,

the

connections are made so that

V1

is

the voltage

drop

across the

fixed

resistor

(R),

and

V2

is

the

drop across

the sensor

(R.).

As

long as

V1 is

not measured on the

2.5V

range,

the

result

is

V2A/1

which

equals

R"/ft.

PABAM.

DATA

NUMBER

TYPE

DESCRIPTION

Repetitions

Range code for

Vr

(Table 9-1)

Range code for

Vz

Ditfeiential channel

number for

first

measurement

Excitation channel

number

Excitation voltage

(millivolts)

lnput

location number

for

first measurement

Multiplier

Otfset

Input locations

altered:

1

per

measurement

***

10

BATTERY

VOLTAGE

***

FUNCTION

This

instruction reads

the

battery

voltage

and

writes

it

to an input

location.

The

units

for

battery voltage are

volts.

When

the

batteries

are around

8

V,

false battery

readings of

9

to

10

V

will

result, and the

quiescent current drain

increases

from 0.7

mA to

7

mA.

At

9.2

to

9.3

V,

false analog

measurements

are

possible

(Example: 2000

mV input is measured as

2010

to

2050

mV).

PARAM.

DATA

NUMBER

TYPE

DESCRIPTION

01:

4

Input location

Input locations

altered:

1

***

11

lOTTHERMISTORPROBE

***

FUNCTION

This

lnstruction

applies

a2VAC

excitation

voltage to Campbell Scientific's Model

107

Thermistor

Probe, makes

a

fast,

single-ended

voltage

measurement across

a

resistor in series

with the thermistor, and calculates

the

temperature in "C

with

a

polynomial. A

1

before

Campbell Scientific CR10 CR10 Measurement and Control - Page 129

Param., Pabam.

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