Campbell 21X Instrukcja Operatora Pobierz pdf (Strona 56)

SECTION

5. TELECOMMUNICATIONS

5.

CR

to datalogger

means

"execute".

6.

CRLF from datalogger

means

"executing

command".

7.

ANY

character

besides a CR

sent to the

datalogger with

a legal

command in its

buffer

causes

the datalogger

to

abort the

command sequence with

CRLF* and

to zero

'the

command buffer.

8. All

commands return

a

response

code,

usually at least

a checksum.

9.

The

checksum includes allcharacters

sent

by

the datalogger

since the last

*,

including

the

echoed command sequence,

excluding

only

the checksum

itself. The

checksum is

formed

by summing

the ASCII

values,

without

parity,

of the transmitted

characters.

The largest

possible

checksum

value

is

8191. Each

time 8191

is

exceeded,

the 21X

starts

the

count

over; e.9., if

the sum of the

ASCII

values is

8192, the checksum is

0.

10.

Commands

that return Campbell

Scientific

binary

format data

(F

and K

commands)

return

a signature

(Appendix

C).

The

21X

sends

ASCII

data

with

8 data bits, no

parity, plus

one

start

bit and one stop bit.

After

answering a ring,

or completing a

command,

the

21X waits about

40

seconds

(147

seconds

in the Remote

Keyboard

State)

for

a

valid

character to

arrive.

lf

a valid character

is

not

received, the 21X "hangs

up".

Some

modems

are

quite

noisy when

not on line; it is

possible

for valid

characters

to appear in

the

noise

pattern.

To insure that

this

situation

does

not

keep the 21X

in telecommunications,

the

21X

counts allthe invalid

characters

it

receives

from

the

time it

answers a ring, and

terminates

communication

after

receiving

150

invalid

characters.

The

21X continues to execute

its

measurement

and

processing

tasks

while

servicing the

telecommunication requests.

lf the

processing

overhead

is

large

(short

execution interval),

the

processing

tasks will slow

the

telecommunication

functions.

In a worst

case

situation, the 21X interrupts the

processing

tasks

to

transmit

a

data

point

every 0.1 second.

The

best

way

to become

familiar with

the

Telecommunication

Commands is to try

them

from

a

terminal

connected to the

21X via

the

SC32A or other modem interface

(Section

6.5).

Telecommunications Commands

are

in

the following Table. The Data Storage

(DSP)

and Telecommunications Modem Pointe

(MPTR)

referred

to

in

the table are described

in

Section

2.1.

TABLE

5.1-1. Telecommunications

Commands

Command Description

A STATUS

-

Datalogger

returns Reference, the DSP location;

the

number

of

filled

Final Storage

locations; Version

of datalogger; Errors #1 and #2 where

r"1J:,'J;#H:i,:l='33trif;,',#:l:#il:1"J;::,'fi

Iffi l:ff itffi

'

characters)that

is the

equivalent of

the

8 bit binary number

shown as the

fiillf:,l:fr:fffl.#fk

on

power-up;

Location of MPrR;and checksum.

R+xxxxx

F+xxxxx Vx

Exx

xx

Mxxxx L+xxxxx

Cxxxx

lf

data

are

stored while

in telecommunications,

the

A

command must

be

issued

to update the Reference

to

the

new

DSP.

[no.

of arrays]B BACK-UP

-

MPTR

is

backed-up

the specified number of output arrays

(no

number

defaults

to 1) and advanced to the

nearest start of array. 21X sends

the

MPTR Location

and Checksum: L+xxxxx

Cxxxx

5-2

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