Campbell 21X Návod k obsluze stáhnout pdf (Strana 121)

SECTION

10. PROCESSING

INSTRUCTIONS

N' is

the number

of input scans

in the last

averaging

period

NT

is

the total

number of input

samples

processed

in

the Output

Interval

INTERMEDIATE

STORAGE REOUIREMENTS

The number

of

Intermediate

locations

will

depend upon

the number of input

values

and

outputs desired:

1.

Define

K

as the number

of input values.

2. Define

S as

the maximum of

either the

variances,

standard deviations,

or C, where

C

=

K if K <

the number of

correlations

requested,

or

C

=

numberof

correlations + 1 if K >

the

number

of

correlations

requested.

3.

Define

Q

as the maximum

of either

the

covariances

or

correlations desired.

4,

Define

P

as the

total

number

of outputs

desired.

The amount

of intermediate memory

locations

(lML)

required,

is then

given

by:

IML=K+S+Q+P+2

EXECUTION TIME

lf

K,

S, and

Q

are

defined

as in

the

previous

section, the execution

time

of the

CV/CR

Instruction in milliseconds

can be approximated

by:

T(ms)

=

1.1K

+ 0.5S

+

0'9Q + 1.8

When evaluating

how frequently input

samples

can be

processed

by

the

CV/CR Instruction

(i.e.,

determining the minimum

program

table

execution

interval),

the time

required

to make

the

measurements

and order the input

values

must be added

to the CV/CR execution

time.

Two alternatives

exist for

the measurement

portion

of

the

programming.

The fastest

method

is

to

group

as many

sensors as

possible

into the

fewest

measurement

instructions, ignoring

the

Input location

order required by the

CV/CR

Instruction.

After

the measurements

are made,

use

"ii1ove"

instructions

(i.e.,

31 and 54)

to

obtain the

proper

input

order.

The

slower

alternative is

to order

separate

measurement

instructions directly

as required by

the CV/CR

Instruction. While

avoiding

"move"

instructions,

this approach

uses more measurement

instructions. The

reason

the first method is in

general

faster is

that less

overhead time is

required

in

going

from

one measurement

to

another within a single instruction

(using

the

"repetitions"

feature)

than in

going

from

one

measurement instruction

to another.

ln many

situations, the 21X

must

perform

measurement

and

processing

tasks

in

addition

to

those associated with

the CV/CR

Instruction.

Uninterrupted operation

of the

CV/CR

Instruction is

assured

by entering

it in Program

Table 1

(highest priority)

and

placing

the

additionaltasks in Program

Table

2.

A covariance correlation

example

is

given

in

Section 8.

***

66 ARCTAN

***

FUNCTION

Calculate the angle

in

degrees whose tangent is

)(/Y. The

polarity

of X and Y

must

be known

to

determine the

quadrant

of the angle,

as shown

here. lf

0

is entered for Parameter

2,

the

Arctangent of

X

is the result

(limits

of the

function

are

-90o

<

ARCTAN <

90o).

Quadrant

Sign of X Sign of Y

l++

ll +

ill

lV+

PAR.

DATA

NO. TYPE DESCRIPTION

4

Input location

of X

txl

4

lnput location

of Y

IYI

4

Destination

input location for

ARCTAN(X

r)

Input locations altered: 1

01:

02:

03:

10-14

1 2 ... 116 117 118 119 120 121 122 123 124 125 126 ... 190 191

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