Campbell Scientific CR10 CR10 Measurement and Control - Page 21

OV2.2

CRlO

INSTRUCTION

TYPES

Figure

OV2.1-1

illustrates

the

use

of

three

different instruction types which act on data.

The fourth

type,

Program Control, is used to

control output times and

vary

program

execution.

Instructions

are

identified by

numbers.

1.

TNPUT/OUTPUT

INSTRUCTIONS

(1-28,

101-104, Section 9)

controlthe

terminal

strip inputs and

outputs

(the

sensor

is

the

source,

Figure

OV1

.1-2), storing

the

results

in Input Storage

(destination).

Multiplier

and

offset

parameters allow conversion

of

linear signals into engineering units. The

Digital

l/O

Ports

are

also addressed

with

l/O

lnstructions.

2.

PROCESSING INSTRUCTIONS

(30-66,

Section

1

0) perform numerical operations

on

values

located

in

Input

Storage

(source)

and store

the

results back

in

Input Storage

(destination). These

instructions

can

be

used

to develop

high level algorithms

to

process measurements prior

to Output

Processing.

3.

OUTPUT

PROCESSING INSTRUCTIONS

(69-82,

Section

11) are the

onlY

instructions which store data in Final

Storage

(destination).

Input Storage

(source) values

are

processed over time

to

obtain

averages,

maxima, minima, etc.

There are two types of processing done by

Output Instructions:

Intermediate

and

Final.

Intermediate processing

normally takes

place each time

the

instruction

is

executed.

For example, when the

Average

Instruction

is

executed,

it

adds the values from

the

input locations being averaged

to

running

totals

in

Intermediate

Storage.

lt

also

keeps

track

of

the

number of samples.

cR10

ovERvlEw

Final processing

occurs only when

the

Output

Flag is

high.

The Output

Processing

Instructions check the

Output

Flag.

lf

the

flag

is high,

finalvalues

are calculated and

output.

With the Average, the

totals

are

divided by

the

number of samples and

the

resulting averages sent

to

Final Storage.

lntermediate

locations are zeroed and the

process starts

over.

The Output Flag, Flag

4

is set high by

a

Program

Control

lnstruction which

must

precede

the

Output

Processing Instructions

in

the

user

entered

program.

4.

PROGRAM CONTROL

INSTRUCTIONS

(83-98,

Section

12)

are

used

for

logic

decisions and conditional

statements. They

can

set flags,

compare

values or times,

execute loops, call subroutines, conditionally

execute

portions

of

the

program, etc.

OV2.3

PROGRAMTABI.ES, EXECUNON

INTERVAL AND

OUTPUT

INTERVALS

Programs are

entered

in

Tables

1

and

2.

Subroutines, called from

Tables

1

and 2, are

entered

in Subroutine Table

3.

The size of each

table

is

flexible,

limited only by the

totalamount

of

program

memory.

lf

Table

1 is

the

only table

programmed,

the entire program

memory

is

available for

Table

1.

Table

1

and

Table 2

have independent

execution

intervals,

entered

in units of seconds

with an

allowable

range

of

1/64 to

8191

seconds.

Subroutine

Table 3

has no execution

interval; subroutines are only executed when

called from

Table

1

or

2.

OV2.3.1

THE EXECUTION INTERVAL

The

execution

interval

specifies

how often

the

program

in

the

table

is executed, which

is

usually determined

by

how often

the

sensors

are

to be

measured.

Unless two

different

measurement rates are

needed,

use

only one

table.

A

program

table

is

executed

sequentially

starting with the

tir:st

instruction

in

the table and

proceeding to

the.end

of

the table.

ov-7

Campbell Scientific CR10 CR10 Measurement and Control - Page 21

ovERvlEw, over.

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