Campbell Scientific CR10 CR10 Measurement and Control - Page 37

SECTION

1.

FUNCTIONAL

MODES

1.1

PROGRAM

TABLES

-

*1, *2,

AND

*3

MODES

Data

acquisition

and processing functions are

controlled by user-entered instructions

contained

in program

tables.

Programming can

be

separated

into 2

tables,

each having its own

user-entered

execution interual.

A third

table

is

available

for

programming subroutines which

may

be

called

by instructions

in

Tables

1 or

2

or

by a special

interrupt. The

*1

and

*2

Modes are

used to access

Tables 1

and

2.

The

*3

Mode

is

used

to

access Subroutine

Table

3.

When a

program

table

is

first

entered,

the

display shows the

table

number

in

the

lD field

and

00

in

the data

field.

Keying

an

"A" will

advance the editor to

the execution

interval.

lf

there

is

an existing

program

in

the

table,

keying

an

instruction location number prior

to

"A" will

advance directly to

the

instruction (e.9.,

5

will

advance to the

fifth

instruction

in

the table).

1.1.1

EXECUTION

INTERVAL

The

execution

interval

is

entered

in units

of

seconds as follows:

1164

...1 seconds, in multiples

ot

1164

(0.015625)

1

......

31.875

seconds,

in multiples

of

1/8 (0.125)

32

.....

8191

seconds, in

multiples

of

1

second

Execution of the

table

is repeated

at

the

rate

determined

by

this

entry.

The table

will

not be

executed

if

0

is

entered.

Entries less than 32

seconds

will be

rounded

to

a

valid interval

if

they are

within

1/512 (0.00195) second of

a

valid interval,

othenrise

error E41

will

be

displayed.

Entries greater than

32

seconds are

rounded to

the

nearest second.

The

sample

rate

for

a

CR10

measurement

is

the

rate

at

which

the

measurement instruction

can

be

executed

(i.e.,

the

measurement made, scaled

with

the

instruction's

rnultiplier.and

offset, and

the

result placed in Input

Storage).

Additional

processing requires extra

time.

The

throughput

rate

is

the

rate

at

which

a

measurement

can

be

made and

the

resulting value

stored

in Final

Storage.

The

maximum

throughput

rate for

fast

single-ended measurements

with

standard

software

is

192 measurements

per

second

(12

measurements

repeated

16

times

per second).

lf

the

specified

execution

interval

for

a

table

is

less than the

time

required

to

process

that

table,

the

CR10

finishes

processing the table

and waits for

the

next ocgurrence

of

the

execution

interval before

again

initiating

the

table

(i.e.i when

the execution

interval has

elapsed and the

table

is still executing, that

execution

is

skipped).

Since

no advantage

is

gained

in

the

rate of execution with this

situation, it should be avoided by specifying

an

execution

interval adequate for the table

processing time,

NOTE:

Whenever

the

processing time

of

the

user's program

exceeds

a

table's

execution

interval, an

error

is logged

in

memory.

The

number of overrun

errors

can

be displayed and reset

in

the

*B

mode

(Section

1.6)

or

using the

Telecommunica-

tions A

command

(Section

5.1).

An overrun

will also cause decimal points

to

appear

on

both sides

of

the

sixth

digit

of

the CRlOKD.

The

decimal points

will

not appear around

the G

in LOG

if

the

*0

Mode

is

entered

before the

overrun

occurs.

In

some cases,

the

processing

time

may exceed

the execution interval only when

the Output

Flag

is

set and extra

time

is

consumed

by

final

Output

Processing. This

may be

acceptable.

For

example, suppose it is desired

to

sample some

phenomena every 0.125 seconds and output

processed data

every

10

minutes. The

processing time of the table which does

this

is

less

than

0.125 seconds except when output

occurs

(every

10

minutes).

With

finaloutput

the

processing

time is

1

second.

With

the execution

interval set at 0.125 seconds, and a one second

lag between samples once

every

10 minutes,

S

measurements out of

4800

(.17"/o)

are

missed:

an acceptable

statistical

error

for

most

populations.

1.1.2

SUBROUTINES

Table

3 is used

to

enter subroutines

which

may

be

called

with

Program

Control

Instructions

in

Tables

1

and 2 or other

subroutines. The

group

of

instructions which

form

a subroutine starts

with

Instruction

85, LabelSubroutine,

and ends

with

lnstruction

95,

End

(Section

12).

1-1

Campbell Scientific CR10 CR10 Measurement and Control - Page 37

Functional

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