Campbell 21X Manuale dell'Operatore Scaricare il pdf (Pagina 40)

SECTION

3. INSTRUCTION

SET BASICS

counter. The

loop

counter

is

added

to

the

indexed value

to

determine the

actual input

location

the

instruction

acts on. Normally

the

loop counter is

incremented

by 1 after

each

pass

through

the loop.

Instruction 90,

Step

Loop Index,

allows

the increment step

to be

changed. See Instructions

87 and

90,

Section

12, for more

details

To

index an input location

(4

digit integer)

key C

after keying

the value

but

before

entering

the

parameter.

Two

minus

signs

(-)

will

be

displayed to the right

of the

parameter.

3.5 VOLTAGE RANGE AND

OVERRANGE DETECTION

The RANGE

code

parameter

on InpuVOutput

Instructions

is used

to specify the full

scale

voltage range

of

the measurement and

the

integration

period

for

the

measurement

(Table

3.5-1).

Select the smallest

full

scale

range

that

is

greater

than or

equal to

the

full

scale output

of

the sensor being measured.

Using the sma

possible

range will result

in the best

resolution

for the measurement.

Two

different

integration

sequences

are

possible.

The

slow integration, 16.67

milliseconds, is

one 60 Hz

cycle

and rejects

noise from 60 Hz AC line

power

as

wellas

having

better

rejection

of random noise

than

fast integration. A PROM

with 50Hz rejection is

available for countries

whose electric utilities

operate at 50Hz

(Appendix

B).

When

a voltage input exceeds the range

programmed,

the value

stored

is

the maximum

negative number,

displayed in

the

*6

Mode

as

-99999.

In output data from

Final

Storage

this

becomes

-6999

in low resolution or

-99999.

in

high resolution.

An

input voltage

greater

than +8

volts

on one of

the

analog

inputs will result

in errors and

possible

overranging on the other analog inputs

Voltages

greater

than 16 volts may

permanently

damage the

21X.

TABLE

3.5-1. lnput

Voltage

Ranges

and

Codes

Range Code

Slow

16.67ms

Integ.

1

2

3

4

5

Full

Scale Range

Fast

250;rs

Integ.

11

t5

millivolts

12

t15

millivolts

13

t50

millivolts

14

t500

millivolts

15

t5000

millivolts

Resolution"

0.33 microvolts

1. microvolts

3.33 microvolts

33.3 microvolts

333. microvolts

*Differential

measurement, resolution

for

single-ended measurement is twice value

shown.

3.6

OUTPUT

PROCESSING

Most Output Processing

Instructions

require

both an intermediate

processing

operation

and

a

final

processing

operation. For

example, when

the Average Instruction,

71

,

is executed,

the

inte rmediate

processing

operation increments a

sample count and

adds

each

new Input

Storage

value to

a cumulative

total

residing

in

lntermediate

Storage.

When the Output

Flag is

set,

the

final

processing

operation divides

the

total by the number

of

sample

counts,

stores

the

resulting average

in Final Storage

and zeros

the

value in

Inlermediate Storage so that the

process

starts

over with

the next

execution.

Final

Storage

is the default

destination

of

data

output

by Output

Processing

Instructions

(Sections

OV1.2,

1.5, 2.1).

Instruction 80 may

be used to direct output to Input Storage or

to

FinalStorage.

Output Processing Instructions

requiring

intermediate

processing

sample the specified

input location(s) each

time the Output

I

3-2

is executed, NOT necessarily

each time the

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