Campbell 21X Manuale dell'Operatore Scaricare il pdf (Pagina 120)

phase

is where

new

input

ived,

the

necessary

squares

or

formed, and

the appropriate

calculated as

required by the

output.

The rate at

which

the

can

be made,

the

input

values

The Input

values are

summation

desired

fina

completed

v{tithout

i nterruption

dete

rmi

nes the

maximum

r4te

of execution

(see

Execution

Time).

The Averagfng Period

Processing

occurs

whenever

tfte

number

of input samples entered

in

Parametdr

7

is

satisfied

or

whenever

an

Output

Intertval

occurs

(i.e.,

whenever the

Output

Flag

is

set).

Results from these

calculationslare stored sequentially

in

Input

Storage

locftions starting

with the

location

specified

in

lParameter

9.

The calculations

performed

dre

shown below,

where N is the

number of

ittrput

samples

in the averaging

period:

1. Means:

=

E)UN

2.V

=

rx2lN

- (DVNp

Deviations:

)

=

Y14trz

Y)

=

!XY/N

-

XX

tY/N2

=

CV(X,Y)/(SD(X)SD(Y))

SECTION

10. PROCESSING INSTRUCTIONS

lf a fast

execution

interval

is

specified,

it is

possible

that the

combined execution

times of

the

input

and averaging

period

processing

may

exceed the

program

table execution

interval.

The

occurrence

of an execution interval

Overrun

(see

Section

2.1 of 21X

Operator's Manual) is

noted

by

decimal

points

on

either

side of the

G

in

LOG

(.0

MODE).

This results in the omission

of one

input

sample.

The

calculations

are

not

affected, however, since

the number of input

samples is incremented

only when valid input

processing

occurs.

Averaging

period processing

occurs

only

when the number of input samples

specified in Parameter

7 is

accumulated.

Regardless

of whether all of the input samples

for

the averaging

period (specified

in Parameter

7)

have occurred

or not, averaging

period

processing

occurs

whenever

the Output

Flag is

set.

This accommodates situations

where the

Output

Interval

may not be

an

integer multiple of

the

averaging

period:

lf for

example a

30 minute

Output

Interval

is

set

by Instruction

92

and an 8

minute

averaging

period

is

specified

by

Parameter

7, then three I minute and one

6

minute

calculations

willoccur.

The

proper

weighting

of these

values

in

producing

the

final

output

is described

below.

The

Output

Processing occurs

only at

the

Output Intervaland

involves

averaging

the

statistical results obtained

at

the averaging

periods.

These

final results

are then stored

sequentially in Input Storage

beginning

with the

location

specified

in Parameter

9.

The Sample

Instruction 70 must be used

to transfer

the data

to

Final

Storage.

All but the last averaging

period

in the Output

Interual willcontain the

same number of input scans

as

specified by

Parameter

7. To insure that results from the

averaging

periods

contribute to the final

result

proportionalto

their averaging

periods,

the

output

processing

uses the following equation:

RF

=

(NR1

+ NR2

+ ....

+ N'RL)/NT

is the final

result

R2, etc., are the

results

from the averaging

period processing

is

the

result from the last averaging

period

in

the Output

Interval

is

the

number of input

samples

in the

specified averaging

period

(Parameter

7)

3.

4.

5.

RF

R1

BL

N

NOTE$:

1.

The

square

root

algorithfn in the

21X returns a

result

of 0 for negative arguments.

2.

The divide

algorithm

returns the

largest

floating

point

number

possible

(ttOte

displayed

as

t99999)

for

a

divide

by

0.

3.

When

computing

the

variance

of a

constant signal,

round off error

producqs

a

small negative

result.

The

21X

returns a 0

for

the

square

root of

4

negative number;

therefore,

the staridard deviation

is set to 0. lf

the sig4al

is

also

used in a

correlaton calculation,

division by

0

returns an

overrange

value

for

the

result.

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