Campbell 21X Instrukcja Operatora Pobierz pdf (Strona 75)

SECTION 7.

MEASUREMENT

PROGRAMMING

EXAMPLES

The

manual for the

101 Probe

gives

the

coefficients of

the sth order

polynomial

used to

convert

the output in

millivolts to temperature

(E

denotes the

power

of 10 by

which the mantissa

is multiplied):

c0

-53.7842

c1

0.147974

c2

-2.18755E-4

c3

2.19046E-7

c4

-1

.1 1341E-10

c5 2.33651E-14

The 21X willonly

allow

5 significant

digits to

the

right

or left o{ the decimal

point

to be

entered

from the keyboard.

The

polynomialcannot

be

applied

exactly as

given

in

the 101

manual. The

initial millivolt reading

must be scaled

if the

coefficients of the higher order terms

are

to

be

entered with the maximum

number

of

significant

digits. lf 0.001

is used as a multiplier on

the

millivolt

output, the coefficients are

divided by

0.001 raised to

the appropriate

power (i.e.,

C0=C0,

C1

=C110.001,

C2=C2/.000001,

etc.).

With this adjustment,

the coefficients

entered

in

Parameters 4-9 of Instruction

55

become:

01:

P4

01: 5

02: 5

03:

1

04:.

1

05: 10

06:

2000

07:

1

08: .001

09: 0

PROGRAM

Excite, Delay,Volt(SE)

Reps

5000 mV

slow Range

lN Chan

Excite all

reps

w/EXchan

1

Delay

(units.01sec)

mV Excitation

Loc

:

Mult

Offset

c0

-53.784

c1 147.97

c2

-218.76

c3 219.05

c4

-111.34

c5

23.365

FIGURE 7.15-1.

101 Thermistor

Probes

Connected to 21X

02: P55 Polynomial

01: 5 Reps

02:

1

X Loc

.03:

1 F(X) Loc:

04:

-53.784

C0

05:

147.97

C1

06:

-218.76

C2

07: 219.05 C3

08:

-111.34

C4

09: 23.365 C5

7.16

MEASURING

107 TEMPERATURE

PROBE

WITH

60 HZ

REJECTION

The 107

temperature

probe

is normally

measured with Instruction 11 which uses the

same measurement sequence

as

lnstruction

5

with

a

fast

integration

voltage

measurement.

The fast

integration does not reject 60 Hz

noise.

In environments where 60

Hz

is a

problem,

the

107

probe

can be measured with

Instruction

5

using the

slow

integration time.

A multiplier of 800 in Instruction

5

is used to

scale the voltage measurement for the

polynomial

Instruction

55

which

is

used

to

convert the

voltage measurement

to

oC.

THERMISTOR

PROBES

EX1

+

Hr I

21X

LO1

Ht2

RED

LEADS

TO

SINGLE ENDED

INPUT

CHANNELS I-5

7-12

1 2 ... 70 71 72 73 74 75 76 77 78 79 80 ... 190 191

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