Moxa Technologies A50 User manual

A50/A51/A60
Dec. 1999 ( 2nd Edition )
All Rights Reserved

Part I -A50/A51 RS-232 to RS-422/RS-485 Converter
A50/A51
RS-232 to RS-422/RS-485
Bidirectional Converter

Part II -A60 RS-232 Surge Protection
A60
RS-232 Surge Protection
Converter

A50/51/60User’sManual
The product described in this manual is furnished under a license agreement and may be
used only in accordance with the terms of the agreements.
Copyright Notice
Copyright 1999 Moxa Technologies Co., Ltd.
All rights reserved.
Reproduction in any form without permission is prohibited.
Trademarks
MOXA is a registered trademark of Moxa Technologies Co., Ltd.
All other trademarks or registered marks in this manual belong to their respective manufacturers.
Disclaimer
Information in this document is subject to change without notice and does not represent a commitment on
the part of Moxa.
Moxa provides this document “as is”, without warranty of any kind, either expressed or implied,
including, but not limited to, the particular purpose. Moxa may make improvements and/or changes in
this manual or in the product(s) and/or the program(s) described in this manual at any time.
Information provided in this manual is intended to be accurate andreliable. However, Moxa Technologies
assumes no responsibility for its use, or for any infringements of rights of the fourth parties which may
result from its use.
This product could include technical or typographical errors. Changes are periodically made to the
information herein; these changes may be incorporated in new editions of the publication.

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The followings are the services we provide.
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TableOfContents
Part I -A50/A51 RS-232 to RS-422/RS-485 Converter
Chapter 1. Introduction ………………………………………. 1
1.1 Overview 1
1.2 Features and Specifications 2
1.3 Package Check List 5
Chapter 2. Installation ……………………………………….. 7
2.1 Installation Procedure 7
2.2 Switch Function Description 7
2.3 LED Indicators 8
2.4 RS-422/RS-485 Pinouts 9
Chapter 3. Operation ………………………………………… 11
3.1 Point-to-point 12
3.2 Multidrop 14
3.3 Simplex/Transmit, Receive 17
3.4 Self Test 19
Appendix A RS-232 Pinouts and Cable Wiring ……………….. 21
Appendix B Impedance Matching and Termination Resistors…… 25
Appendix C Troubleshooting …………………………………. 27

TableOfContents
Part II -A60 RS-232 Surge Protection
Chapter 1. Introduction…………………………………………… 29
1.1 Overview 30
1.2 Features and Specifications 30
1.3 Package Check List 31
Chapter 2. Installation……………………………………………… 33
2.1 Installation Procedure 33
2.2 LED Indicators 34
2.3 Self Test 36
Appendix A RS-232 Pinouts and Cable Wiring…………………… 37
Appendix B Troubleshooting ……………………………………….. 41

11-1
1
1
1 Introduction
Overview
The MOXA RS-232 to RS-422/RS-485 bidirectional converters, A50 and A51, are
designed to convert unbalanced (single-ended) RS-232 signals to balanced
(differential) RS-422/RS-485 signals, and vice versa. They are the best choices for
those who want to control devices at longer distance and/or to communicate with
several devices via merely one link, particularly in the industry area. Point-to-point,
multidrop and simplex operations are available for most users' needs.
Outlook of A50
RS-422/485
RJ-45 Connector
Power Jack
RS-232
RJ-45 Connector

1-2
Outlook of A51
Features and Specifications
Features
Both A50 and A51 are RS-232 to RS-422/RS-485 bidirectional converters except
that A51 has one more feature: isolation protection, which provides high voltage
protection up to 2000V.
All the switches, SW1 and SW2, of A50/A51 are designed to be inside of the
converter to protect switch settings from unintended change and introducing
communication error without any warning. Hence, it is necessary to take the two
screws off and open the cover up if you need to change the operation mode via
sliding the switches.
The A50/A51 must be powered either from a DC +9V to +30V,
150mA power adapter or the pin 6 andpin 7 of the Terminal Block.
LED indicators are provided to show the status of data transmitting/receiving, RTS
signal and Power.
To avoid over-current from the remote ground to converter's ground, an protect
resistor has been added inside the A50/A51.
Specifications
vPower Supply -DC +9V to +30V, 150mA
vData Rate -Up to 921600 bps under 500 ft (0.15 Km)
vDistance -Up to 4000 ft (1.2 Km) under 115200 bps
vRS-232 RJ-45 Connector -
Supports TxD, RxD, DTR, DSR, RTS, CTS, DCD, GND
vRS-422/RS-485 RJ-45 Connector -
RS-422/485
RJ-45 Connector
Power Jack
RS-232
RJ-45 Connector

Introduction
1-3
Supports TxDA, TxDB, RxDA, RxDB, GND
vRS-422/RS-485 Terminal Block Connector -
Supports TxDA, TxDB, RxDA, RxDB, GND, PWR, PWR GND
vSwitch -SW1 : for full/half-duplex mode
SW2 : for Tx (driver) and Rx (receiver) state
vIsolation Protection -for A51 only, up to 2000V.
vTerminal Resistor -RT1 space reserved for RS-422/RS-485 receiver signal.
vMounting Kit -Plastic Plates and screws for mounting A50/A51 on the wall or
any surface.
RS-422/485 RS-232
Mounting
Screw
FixingScrew
A50/A51 with Mounting Kit
Package Check List
Upon unpacking your A50 or A51 package, you should find the following items:
vA50 (or A51) RS-232 to RS-422/RS-485 bidirectional converter (with isolation
protection if A51)
vOne power adapter
vMounting Kit
vA50/A51/A60 User's Manual

1-4

Introduction
1-5

12-1
2
2
2 Installation
Installation Procedure
As RS-232 or RS-422/RS-485 port are labeled clearly on the surface of the A50/A51
converter, please prepare the RS-232 cable (refer to Appendix A, RS-232 Cable
Wiring) and decide the operation mode as well as 2/4-wire cable (refer to Chapter 3,
Operation) in advance.
Take off the two screws on top of the converter and open the cover up if you need to
change the operation mode via sliding the switches.
Switch Function Description
Inside look of A50/A51
AUTO
485
RTS
422
JP

2-2
Switch settings table of SW1 and SW2 is as follows:
SW1
*Full-duplex mode Off
Half-duplex mode On
SW2 Pin1 Pin2 Pin3
Pin4
*TxD always enabled On Off XX
TxD always disabled Off Off XX
TxD enabled by RTS Off On XX
*RxD always enabled XXOn Off
RxD enabled by /RTS XXOff On
Note: ‘ * ‘ means default settings , ‘ X ‘ means don’t care
LED Indicators
There are LED indicators for TxD, RxD, RTS, and PWR on top of A50/A51. The
indicator is not lighted on when not connected with signal or power. On the contrary,
it will be lighted on and be in one of the red, green or orange colors.
TxD indicator stands for data transmitting from RS-232 to RS-422/RS-485. It
shows green when connected and no data transmitting. It shows orange when
connected and transmitting data.
RxD indicator stands for data transmitting from RS-422/RS-485 to RS-232. It shows
red when connected and no data received. It shows orange when connected and
receiving data (In half-duplex mode, it shows red when line is not connected due to
the characteristics of ICs for RS-485).
RTS indicator is for RS-232 RTS signal. It shows red when connected and RTS
signal turned on. It shows green when connected and RTS signal turned off.
PWR indicator is red when power is on and not lighted when power is off or not
connected.

Installation
2-3
RS-422/RS-485 Pinouts
RS-422/RS-485 interface with RJ-45 Jack connector or Terminal Block Connector is
depicted as follows.
A50/A51 A50/A51
RJ-45 Jack Terminal Block
Connector Pinouts Signals Connector Pinouts Signals
1 nc 1 TxD B
2 nc 2 TxD A
3 GND 3 RxD B
4 TxD B 4 RxD A
5 TxD A 5 GND
6 RxD A 6 Power GND
7 RxD B 7 Power Input
8 GND
9 nc
10 nc(not connected)
Note : Pin 6 and Pin 7 of Terminal Block are for Power GND and Power Input,
which is an alternate option for power adapter. Be careful that DO NOT
confuse RS-422/RS-485 GND with Power GND.
Note : Under half-duplex mode (SW1 in ON mode), the couples of (TxD B,
RxD B) and (TxD A, RxD A) are shorted inside the converter for
convenience. Users can save the trouble with shorting the wires.
1 2 3 4 5 6 7
RJ-45 Connector Terminal Block Connector
1 2 3 4 5 6 7 8 9 10

2-4

A3-1
3
3
3 Operation
The A50 (or A51) supports 5 kinds of operations. They are:
vPoint-to-point/4-wire Full Duplex
vPoint-to-point/2-wire Half Duplex
vMultidrop/4-wire Full Duplex
vMultidrop/2-wire Half Duplex
vSimplex/Transmit, Receive Only
All the operations are to be described below. And TA, TB, RA and RB represent
TxD A, TxD B, RxD A and RxD B signal lines of the RJ-45 RS-422/RS-485
connector or the Terminal Block, respectively.
Note : If possible, connect GND of both sides together to gain better signals. That
is, you may need one more GND connection in addition to 4-wire or 2-wire
connection.
Note : For A51, connecting GND at the Terminal Block to the earth ground to
provide a ground path to prevent electric shock caused by lightning, no
matter RJ-45 or Terminal Block RS-422/RS-485 is used.

3-2
Point-to-point
Point-to-point configuration means two devices which locate at two different places
can be linked together to communicate through a couple of A50 (or A51) converters.
4-wire Full Duplex
In the graph, TA, TB, RA and RB could be either from RJ-45 or Terminal Block.
The settings of the switches for each A50 (or A51) are as follows:
SW1 SW2 Pin1
Pin2 Pin3 Pin4
Full-duplex mode Off TxD always enabled On Off XX
RxD always enabled XXOn Off
2-wire Half Duplex
In the graph, TA, TB, RA and RB could be either from RJ-45 or Terminal Block.
The settings of the switches for each A50 (or A51) are as follows:
SW1 SW2 Pin1
Pin2 Pin3 Pin4
Half-duplex mode On TxD enabled by RTS Off On XX
RxD enabled by / RTS XXOff On
A50/A51A50/A51
RS-232
RA
RB RS-422/ RS-232
TB RS-485
TA
GND
TA
RS-422/ TB
RS-485 RB
RA
GND
DTE/
DCE DTE/ DCE
A50/A51
RA
RB RS-232
TB
TA
GND
DTE/
DCE
A50/A51
RS-232
TA
TB
RB
RA
GND
DTE/
DCE
RS-485 RS-485