Campbell Scientific CR10 CR10 Measurement and Control - Page 111

SECTION

8.

PROCESSING

AND

PROGRAM CONTROL EXAMPLES

The following examples

are

intended

to

illustrate the use of Processing and Program

Control

lnstructions,

flags, dual

Final

Storage,

and

the capability to direct

the

results of Output Processing

lnstructions to

lnput

Storage.

The

specific

examples

may

not

be as important

as

some

of

the

techniques

employed,

for example:

Directing

Output

Processing to

Input

Storage

is

used

in

the Running

Average and

Rainfall

lntensity

examples

(8.1

and

8.2).

Flag

tests

are

used

in

the Running

Average, lnterrupt

Subroutine,

Converting

Wind Direction,

and

Saving Data

Priorto

Event

examples

(8.1,8.5,8.7

and 8.8).

Control

ports

and

the Loop are illustrated

in

the

AM32

example

(8.3).

An algorithm

for

a

down counter

is

used

in

the Saving Data Prior to Event example

(8.8).

As

in

Section 7

these examples are not complete

programs

to

be

taken

verbatim.

They

need

to

be

altered to fit specific needs.

8.1

COMPUTATION OF

RUNNING

AVERAGE

It is

sometimes

necessary to compute

a

running

average (i.e., the average covers

a

fixed

number of samples

and

is

continuously

updated

as

new samples are

taken).

Because

the

output interval

is

shoder

than the averaging

period,

lnstruction 71

cannot

be used;

the

algorithm for computing this

average

must

be

programmed by

the

user.

The following

example

demonstrates a

program

for

computing

a running

average.

In

this

example,

each

time a

new measurement

is made (in

this

case

a

thermocouple

temperature)

an

average is computed for

the

10

most recent

samples.

This

is

done by saving all

10

temperatures

in

contiguous

input locations

and using

the SpatialAverage lnstruction

(51)

to compute

the

average.

The temperatures are

stored in locations

11

through

20.

Each

time

the

table

is executed,

the

new measurement

is

stored in location

20

and the

average

is

stored

in location

2.

The

Block Move Instruction (5a)

is

then

used

to

move the temperatures

from

locations

12

through 20 down

by

1

location; the

oldest

measurement (in

location

1

1)

is lost

when the temperature

from location

12

is

written

over

it.

lnput

Location Labels;

1:PanlTemp

1S:Temp i-5

2:10smplav

16:Temp i-4

1

1:Temp

i-9

17:Temp i-3

l2:Temp

i-8

18:Temp i-2

13:Temp

i-7

19:Temp

i-1

14:Temp

i-6

2O:Temp

i

Where i is current reading,

i-l

is

previous

reading,

etc.

"

1

TablelPrograms

01: 10

Sec. Execution

lnterval

01:

P17

01:

1

P14

1

1

1

1

1

20

1

0

P51

10

11

2

02:

01:

02;

03:

04:

05:

06:

07:

08:

03:

01:

02:

03:

Panel

Temperature

Loc

[:PanlTemp]

Thermocouple Temp

(DIFF)

Rep

2.5

mV

slow

Range

lN Chan

Type

T

(Copper-Constantan)

Ref

Temp Loc

Panl

Temp

Loc

[:Temp

i

]

Mult

Offset

SpatialAverage

Swath

First Loc

Temp

i-9

Avg

Loc

[:1Osmplav]

8-l

Campbell Scientific CR10 CR10 Measurement and Control - Page 111

PanlTemp, 10smplav

Page 111 highlights