Campbell Scientific CR10 CR10 Measurement and Control - Page 88

1H

1L

CR1

O

5H

5L

@

@

@

@

@

107

PROBE

SECTION

7.

MEASUREMENT

PROGRAMMING

EXAMPLES

J_BOX

cu-

co-

FIGURE

7.4-1. Thermocouples

with.

External

Reference

Junction

@

v\-/

@

@

@

@cu

In

the following example, an

externaltemperature

measurement is used as

the

reference

for

5

thermocouple measurements.

A Campbell

Scientific

107

Temperature

Probe is used

to

measure

the

reference

temperature. The

connection

scheme

is

shown in Figure 7.4-1.

lf

a

more

accurate

reference

temperature

is

needed, Campbell Scientific's

TCRG

utilizes a

100

ohm

PRT

to

measure

the

reference

temperature and provides better insulation for a

more isothermal reference.

The

temperature

("C)

of

the

107 Probe

is

stored

in

lnput

Location

1

and the thermocouple

temperatures

('C)

in Locations 2-6.

PROGRAM

Temp

107 Probe

Rep

lN Chan

Excite

all

reps

w/EXchan

1

Loc

[:REF

TEMP

]

Mult

Offset

Thermocouple Temp

(DIFF)

Reps

7.5 mV

60

Hz rejection Range

lN Chan

Type

T

(Copper-

Constantan)

Ref

Temp

Loc REF TEMP

Loc

[:TC

#1

]

Mult

Offset

COPPER

CONSTANTAN

7.5

107

TEMPERATURE

PROBE

Instruction

1

1

excites Campbell Scientific's

107

Thermistor

Probe

(or

the

thermistor

portion

of

temperature and relative humidity probe) with

a

excitation, makes a single

ended

measurement

calculates,temperature ("C)

with

a

fifth order

polynomial;-

In

this example, the temperatures

obtained from

three

107

probes.

The

are

made on single-ended

channels

1-3

and

the

temperatures are stored

in

Input

Locations

1-3.

CONNECTIONS

The

black leads from

the

probes

go

to

excitation

channel

1,

the

purple leads

go

to

analog ground (AG), the

clear

leads go to

ground (G), and

the

red leads

go

to single-

ended

channels

1,

2, and

3

(channel

1H,

channel

1L,

and channel

2H,

respectively).

PROGRAM

Temp

107 Probe

Reps

lN

Chan

Excite

all

reps

w/EXchan

1

Loc

[:107

T #1

]

Mult

Offset

01:

01:

02:

03:

o4:

05:

06:

01:

P11

01:

1

02:

11

03:

1

04:

1

05:

1

06:

0

02:

P14

01:

5

02:

22

03:

1

04:

1

05:

1

06:

2

07:

1

08:

0

P11

3

1

7.6

207

TEMPERATURE AND

RH

PROBE

lnstruction

12

excites and measures

the

RH

portion of the Campbell Scientific 207

Temperature and Relative Humidity

probe.

This

instruction relies on

a

previously measured

temperature

('C)

to

compute

RH

from

the

probe

resistance.

Instruction 11 is used to obtain the

7-4

Campbell Scientific CR10 CR10 Measurement and Control - Page 88

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