Campbell 21X Instrukcja Operatora Pobierz pdf (Strona 130)

SECTION

12. PROGRAM

CONTROL INSTRUCTIONS

delay of 0 means

that there is

delay

between

passes

through the loop. Each

time the

table is executed

all iterations

the loop will

completed

and execution

will

pass

on to the following

instructions.

the delay is

5, every fifth

time

that

the

execution interval

comes

up, one

pass

through

the

loop

is made;

only those

instructions

the loop will

be executed and

other

portions

of the table

are not

executed

the

interim.

When

the loop

executed,

execution

starts at

the

loop,

skipping over

any

instructions

in the

table.

When

a fixed number

of iterations

are executed,

the

time spent in

the loop is

equal to

the

product

of the execution interval,

delay,

and

the

number

of iterations. For

example,

a loop with a delay of

and a count

of 5 will

take 5 seconds

the

execution interval

is 1

second. When the loop is

first entered,

one

pass

through the loop

made,

then the 21X

delays untilthe next

execution

interval

and makes

the second

pass

through

the

loop.

After making

the fifth

pass

through the

loop,

there is the fifth

delay, after which

execution

passes

the

instruction

following the

END

instruction

which

goes

with

the loop.

While

in a loop with

delay,

the table will

not

initiated

at each execution interval.

(However,

the overrun

decimals will not

be displayed.)

Some consequences

of this

are: The

Output

Flag will

not

be automatically

cleared between

passes

through

the loop. Because

Table

cannot interrupt

Table 1, Table

2 will not be

executed while Table

1 is in

loop

with

delay.

Table

1 will not interrupt

Table

2 in the

middle

output array. Thus,

if the Output Flag is set in

Table

prior

to entering the loop

or within the

loop, the

flag

must

be specifically

cleared before

the end of the

pass

or Table 1

will not be able to

interrupt.

Input locations for

Processing

lnstructions within

loop can

be entered

as Indexed locations. An

Indexed location

causes the input

location to be

incremented by 1 with

each

pass

through the

loop.

(The

lndex counter

is added

to the

location number

the

program

table.)

lnput

locations which

are not indexed

will remain

constant.

To specify

Indexed location,

depress

the C

key

at some

point

while

keying in

the digits for

the input location and

before entering the

location with

the A

key.

Two dashes,

--,

appear

the two right

most

characters

of the display,

indicating

the entry

is lndexed.

When

the same output

processing

is requiied

values in

sequential

input locations,

it must

accomplished

by using

the repetitions

of the Output Instruction, not

indexing

the

input location within a loop.

Output Instruction

within

a loop is allotted

same number

Intermediate

Storage

locations

as it would receive if it were not in

the

loop.

For

example, the Average instruction with

a single

repetition is

allotted

only two Intermediate

locations:

one

for the number of samples

and

one for the running total. Each time through the

loop

the sample counter

is incremented

and the

value in the referenced

input

location is added

the total. lf the input

location is indexed,

the

values from

all

input

locations

are added to the

same total. lf the Average

instruction

with 1

repetition

and

location

1 indexed

placed

a loop of 10 and the Output

Flag

set high

prior

entering the loop, 10

values will

be output.

These will

not be the

averages for locations 1-

10. The first will

the average of all the

readings in

locations

1-10 since

the

output. Because

the

Intermediate locations

are

zeroed each

time an

output occurs, the next

nine values will

be the

current values

(samples

at the time

of output)

of Locations 2-10.

Loops

can be nested.

Indexed locations within

nested

loops are indexed to the inner most loop

that

they are

within. The maximum nesting

the 21X is 9 deep.

This

applies to lf

Then/Else

comparisons and

Loops

or any

combination

thereof.

lf Then/Else

comparison which

uses

the Else lnstruction,

counts

as being

nested 2 deep.

PAR. DATA

NO. TYPE DESCRIPTION

Delay

4 lteration count

The

following example

involves

the use of the

Loop Instruction,

without a delay, to

perform

block data transformation.

01:

02:

12-2

1 2 ... 125 126 127 128 129 130 131 132 133 134 135 ... 190 191

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