Campbell 21X Instrukcja Operatora Pobierz pdf (Strona 61)

6.5.1 SC32A

Most

,

terminals,

and

printers

require

the SC32A

lsolated RS232

lnterface

for

a

"direct"

to the

21X. The SC32A

raises the

21X's ring

line when

it

receives

characters

frpm the computer

or

terminal, and

conveds

the 21X's

logic levels

(0V

logic

low, 5V

logic high) td RS232

logic

levels.

The

SC32A

P5

pin

port

is configured

as

Data

Equipment

(DCE)

which

allows

to Data Terminal

Equipment

SECTION 6.

9

PIN

SERIAL

INPUIIOUTPUT

Table

6.5-1 lists

the most common

RS232

configuration

for

Data Terminal Equipment.

TABLE 6.5-1.

DTE

Pin

Configuration

PIN

=

25-pin connector

number

ABR

=

Abbreviation

for the

function

name

O

=

SignalOut

of

the terminalto

another

device

|

=

Signal lnto

the

terminalfrom

another

device

PIN

2

ABR YO FUNCTION

direct

(DrE),

includes

most

PCs and

printers.

For to

DCE

devices

such as

modems some

computers,

a

null

modem

cable is

reqqired.

When the SC32A

receives

a character

from the

computer

or terminal

(pin

2), 5V

is

applied

to

the

datalogger

fling

line

(pin

3)

for

one

second

or

untilthe

Mo{em

Enable line

(ME) goes

high.

The 21X

wafts approximately

40

seconds

to

receive carrif,ge

returns,

which

it

uses

to

establish

baird rate.

After the

baud rate

is set

the 21X

tra4bmits

a carriage

return, line

feed,

*,

and enters

the Telecommunications

Command

State

(Secti$n

5).

lf the carriage

returns

are not

received

within the

40

seconds,

the 21X

"hangs

up"

oTD Transmitted

Data:

Data

is

transmitted

from the terminal

on this

line.

Received

Data:

Data is

received by the

terminal

on

this

line.

Request to Send:

The

terminal

raises

this line to

ask

a

receiving

device

if

the

terminal

can

transmit data.

Clear

to

Send:

The receiving

device

raises this

line

to

let

the terminal

know

that the

receiving device

is

ready

to

accept

data.

Data

Terminal

Ready:

The

terminal

raises

this line to

tell

the

modem to

connect

itself

to the

telephone

line.

Data Set

Ready:

The

modem

raises

this line to

tell

the terminalthat

the modem

is

connected

to the

phone

line.

Data

Carrier

Detect: The

modem raises

this

line to

tell the

terminal

that

the

modem is

receiving a

valid

carrier

signal from the

phone

line.

Ring

Indicator:

The modem

raises

this line

to tellthe

terminal that

the

phone

is

ringing.

Signal

Ground:

Voltages are

measured

relative to

this

point.

NOTE: The

SC32A

has a

jumper.

With

the

jumper

{n

place

the SC32A

blocks

printer

data

an{

passes

data only

when

the

21X

is

in Telecbmmunications.

RD

RTS

O

CTS

I

DTR

O

DSR

I

DCD

I

6.5.2 COMPUTER/TERMINAL

REQUIREMENTS

Computers,

terminals

and

printers

are

usually

configured

{s

Data

Terminal

Equipment

(DTE).

Pins 4 and

20

are used

as

handshake

lines,

which

are

set high

when the

serial

port

is

enabled.

Pbwer for the SC32A

is

taken

from

these

pins.

For equipment

configured

as

DTE

a

direct ribbortr

cable

connects

the modem/terminal

to the

SC3aA. Clear

to Send

(CTS)

pin

5, Data

Set Ready

{DSR)

pin

6, and

Received

Line

Signal Detept

(RLSD)

pin

8 are

held

high by the

SC32A

(whbn

the

RS232 section

is

powered)

which

should satisfy

hardware

handshake

requ iremenfs

of

the modem/terminal.

22

SG

6-3

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