Campbell 21X Manuel de l'opérateur télécharger pdf (Page 37)

SECTION 2.

INTERNAL

DATA

STORAGE

The

Data Storage

Pointer

(DSP)

is used

to

determine where

to

store

each

new data

point

in

the Final Storage

area.

The

DSP

advances to

the next available

memory location

alter

each

new

data

point

is

stored.

The

DPTR

is

used

to

recall

data

to

the

LCD

display. The

positioning

of this

pointer

and data

recallare

controlled

from the keyboard

(*7

Mode).

The

TPTR is used

to

control

data

transmission

to a

cassette tape recorder.

When on-line

tape

transfer is activated

(.4

Mode

or Instruction

96,

option

O0), data is

transmitted to

tape

whenever

the DSP is a minimum

of 512

memory

locations

ahead

of the TPTR.

The

TPTR

may also be

positioned

via

the keyboard for

manually

initiated

data

transfer to tape

(.8

Mode).

The PPTR is used

to control data

transmission

to a

printer,

Storage Module,

or other serial

device. Whenever

on-line

printer

transfer

is

activated

(.4

Mode

or

Instruction

96), data

between the PPTR

and

DSP

are

transmitted.

When

on-line transfer to a

SM192/716 Storage

Module is activated

by

Instruction

96

with

output

code

30,

data is

transmitted each

time

an

output

array is stored in FinalStorage

lF THE

STORAGE

MODULE IS

CONNECTED TO THE

21X. ll the Storage

Module

is

not

connected,

the 21X does not

transmit the

data nor does it

advance the PPTR

to the new DSP location.

lt

saves

the

data untilthe

Storage Module is

connected. Then,

during

the next

execution of

Instruction

96, the 21X outputs

all of

the

data

between the PPTR

and

the DSP

and updates

the PPTR to the DSP location

(Section

4.1)

The

MPTR

is

used in transmitting

data over

a

telecommunications

interface. When

Telecommunications

is

first

entered, the MPTR

is set

to

the

same location as

the DSP.

Positioning

of the MPTR is

then controlled

by

commands from

the external calling device

(Section

5.1).

2-2

NOTE: All memory

pointers

are set to

the

DSP

location

when

the datalogger

a

program.

For this reason,

ALWAYS

RETRIEVE UNCOLLECTED DATA

BEFORE

MAKING

PROGRAM

CHANGES.

For

example,

assume the TPTR lags

the

DSP by less

than 512 data

points

when

the

datalogger

program

is

altered. On

compiling, the TPTR

is

positioned

with

the

DSP, losing reference

to the data that was

intended to

be transferred to tape.

The

data

is

not automatically

transferred and

appears

as

a discontinuity in the data

file.

Untilthe

ring

memory

wraps

around and

data

overwrite

occurs,

the

data

may

be

recovered

using

the.8

Mode.

This

scenario

is

also true

for

the PPTR and data

intended for

a Storage

Module.

2.2

DATA OUTPUT

FORMAT

AND

RANGE LIMITS

Data

are stored internally in Campbell

Scientific's Final

Storage

Format

(Appendix

C.2). Data may be

sent

to Final

Storage

in

either

LOW

RESOLUTION

or

HIGH

RESOLUTION format. Low resolution is

the

default.

To

change

the

resolution, Instruction

(Section

1 1) must

precede

the Output

Instructions in

the

program

table.

2.2.1

RESOLUTION AND

RANGE

LIMITS

Low

resolution data is

a 2

byte format

with

3 or

significant digits and a

maximum

magnitude of

t6999.

High

resolution data is

a

4 byte format

with

5 significant digits and a maximum

output

value

of

t99999

(see

Table

2.2-1

below).

TABLE 2.2-1.

Resolution Range

Limits

of

21X

Data

Minimum

Resolution

Zero

Magnitude

Low 0.000 +0.001

0.0000

+.00001

Maximum

1 2 ... 32 33 34 35 36 37 38 39 40 41 42 ... 190 191

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