Campbell 21X Manuale dell'Operatore Scaricare il pdf (Pagina 39)

The

SECTION

3. INSTRUCTION SET

BASICS

used to

program

the

21X

are divided

into

4

types:

lnput/Output

(l/O),

Processing,

Output and

Program

Control. l/O lnstructions are used to

make measurements and

store the

in input

locations or

to

initiate analog

or digital

pott

output.

Processing

lnstructions

numerical operations using

data from

lnput

Storage

locations

and

place

the

method for

gjenerating

time

or event

dependent

data

summaries from

processed

sensor

readings

residing

in sfiecified lnput Storage

locations. Program Control lnstructions

are used

to

direct

program

ex*ution

based on

time and/or conditional

tests on input data and to

direct

output

to

erternaldedces.

lnstructions

Are

identified

by

a number. Each instruction

has

a

number of

parameters

which

give

the

21X the

lnformation

it needs to execute the

instruction.

l

The

set

of inbtructions available

in

the 2lX is determined

by

the

Programmable Read Only

Memory

chifis

(PROMS)

that are

installed.

Appendix

B lists

the

software options available.

3.1 PARAMETER

DATA

TYPES

There are 3

flifferent

data types

used

for

Instruction

pprameters:

Floating

Point

(FP),

4

digit

integer{

(4),

and 2 digit

integers

(2).

In the

listings of th$

instruction

parameters

(Sections

9-12), the

data type

is

identified

by

its

allow

the

21

Different

data

types

are

used to

to

make

the most

efficient

use

of

its memory.

Floating

Point

parameters

are used to enter

numeric

conbtants for calibrations

or

arithmetic

operations.

[A/hile

it is

only

possible

to

enter 5

digits

(magnftude t.00001

to

t99999.),

the

internalfornlat

has

a

much

greater

range

(1x10-ts

to

Qx1018,

Section

2.2.1).

3.2

REPETITIONS

The repetitiqns

parameter

on

many of the l/O,

Processing,

and Output

Processing

lnstructions

is

used

to

repeat

the

instruction

on a number of

sequential

lflput

Channels

or

lnput Storage

locations.

For example, if

you

have 4

ditferential

voltage meapurements

to make

on the

same

voltage

rangp,

wire

the

inputs to

sequential

channels

anp

instead

of

entering

the Ditferential

Voltage

Me{surement

Instruction

4 times, enter

it once

with

fr

repetitions. The

instruction will

make

4 me{surements starting

on

the

specified

channel

number

and

continuing

through the

3

succeeding

pifferential

channels,

with

the

results

being

store(

in the

specified

input location and

the

3 succe$ding

input

locations.

Averages for

all

4 measuiements

can be calculated

by

entering the

Average Instruction with

4

repetitions-

When

several

of the

same

type

of

measurements

are

to be made but the

calibrations of the

sensors are different,

it

requires less time to use a single

measurement

instruction

with

repetitions

and

then apply

the

calibrations

with Instruction 53 than

it

does

to

enter

the

instruction several times

in order

to

use

different

multipliers and offsets.

This is

due

to

the set

up and

calibration

time

for

each

measurement instruction. However,

if time

is

not

a constraint,

separate instructions

may

make

the

program

easier to

follow.

3.3

ENTERING

NEGATIVE NUMBERS

After

keying

in a number,

press

C or

"-"

to

change the number's

sign.

On

floating

point

numbers a minus sign

O

will

appear

to the

left

of

the number.

Excitation voltages

in

millivolts

for l/O

Instructions

are

4 digit

integers;when C

is

pressed,

minus signs

(-)

will appear

to the

right

of

the

number

indicating

a

negative excitation.

Even

though

this display is the same

as that

indicating an indexed

input

location,

(Section

3.4) there

is no indexing

effect

on excitation

voltage.

3.4

INDEXING INPUT LOCATIONS

When

used

within a

Loop,

the

parameters

for

input

locations

can be

Indexed

to

the loop

3-1

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 ... 190 191

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