Installation; Serial Communication Adaptors For Personal Computers; Five-Wire Configuration; Three-Wire Configuration - ABB 4620 User Manual

3 INSTALLATION

Observe the limitations outlined in the Operating Instructions –
see Section 1. The maximum serial data transmission line
length for both RS422 and RS485 systems is 1200m.
3.1 Serial Communication
Adaptors for Personal Computers
An RS422/485 communications adaptor board is required for
serial links. It is strongly recommended that the card used has
galvanic isolation to protect the computer from lightning
damage and increase immunity from noise pick-up from
cables.

3.1.1 Five-wire Configuration

The following OPTO22 boards are recommended for use with
the 4600 serial instruments:
Part No. ComputerType
AC24 XT Bus IBM PC compatible
AC24 AT AT Bus IBM PC compatible
AC34 Microchannel IBM PC.
The following 'jumper' selections are required on OPTO22
boards (usually supplied as the default configuration):
RX & TX install line termination jumper
Install pull-up and pull-down jumpers
CTS & RTS disable jumper installed.
Select board address and interrupts as described in the
OPTO22 manual.

3.1.2 Three-wire Configuration

The adaptor card must have the provision for disabling the
transmitter after each message is transmitted, so that bus
contention does not occur. This is often implemented by the
use of the RTS signal to control the transmitter enable. Consult
the adaptor card manufacturer to determine suitability.
Caution. Install the pull-up/pull-down resistors
on either the RX TX lines. The resistors
or
connected on pairs of lines.
both
Computer Terminal or
Host Computer

4 ELECTRICAL CONNECTIONS

All connections,
communication, are made as shown in Figs. 4.3 and 4.4 of the
Operating Instructions – see Section 1.
4.1 Serial Connections – Figs. 4.1 and 4.2
The transmitters must be connected in parallel as shown in the
schematic diagram – Fig. 4.1. The RS485 standard quotes
connection of maximum thirty two slaves (4600 Transmitters)
to any single driver (computer terminal or host computer); the
RS422 standard quotes connection of up to ten slaves.
However, these numbers can be increased if the driver's serial
port permits.
Make serial data connections and check the processor board
links as shown in Fig. 4.2. The type of cable used is dependent
on the transmission speed and cable length:

4.1.1 Five-wire Cable

(refer also to Fig. 11.1)
Up to 6m (all speeds)
cable.
Up to 300m
integral drain wire, e.g. Belden 9502 or equivalent
Up to 1200m
and integral drain wires for each pair, e.g. Belden 9729 or
equivalent
4.1.2 Three-wire Cable (refer also to Fig. 11.2)
Up to 6m (all speeds)
cable.
Up to 1200m
and integral drain wire, e.g. Belden 9501 or equivalent.
be
must not
Chain of 4600 Transmitters
(Connected)
Fig. 4.1 Schematic Diagram
apart from those
– standard screened or twisted pair
– twin twisted pair with overall foil screen and an
– twin twisted pair with separate foil screens
– standard screened or twisted pair
– single twisted pair with overall foil screen
Termination Resistor
(on 4600s receive input)
Last 4600
in Chain
for serial data
3