Amplicon USB232U User manual

USB232U/485Ui
USB232U/485Ui
USB TO RS232 / RS485
SERIAL
COMMUNICATIONS
INTERFACE
W ITH ISOLATION
OPTION
This Instruction Manual is supplied with the USB232U/485Ui Adapter to provide the user with sufficient information to
utilise the purchased product in a proper and efficient manner. The information contained has been reviewed and is
believed to be accurate and reliable, however Amplicon Liveline Limited accepts no responsibility for any problems
caused by errors or omissions. Specifications and instructions are subject to change without notice.
USB232U/485Ui Instruction Manual Issue A2
© Amplicon Liveline Limited
Prepared by Helen Elcock
See www.amplicon.co.uk for updates

USB232U/485Ui
DECLARATION OF CONFORMITY
MEV LIMITED
SUITE 8, BAXALL BUSINESS CENTRE
ADSWOOD ROAD
STOCKPORT SK3 8LF UK
We declare that the product(s) described in th
is Instruction Manual
perform in conformity with the following standards or standardisation
documents:
Electro Magnetic Compatibility (EMC):
EMC Directive 89/336/EMC
CE Directive 93/68/EEC
David Cooper, MIEE
Director
MEV Limited

USB232U/485Ui
LIST OF CONTENTS
PARA SUBJECT PAGE
1INTRODUCTION ..................................................................................................................1
1.1 The Products Described in this Manual .................................................................................1
1.2 Features of the USB232U/485Ui Series of Data Communications Interfaces ........................1
1.3 General Description ..............................................................................................................2
1.3.1 Enhanced Features...............................................................................................................3
1.4 What the Package Contains..................................................................................................3
1.4.1 The Amplicon Warranty Covering the USB232U/485Ui interfaces.........................................3
1.4.2 Contacting Amplicon Liveline Limited for Technical Support or Service ................................3
1.4.3 Technical Support.................................................................................................................4
1.4.4 Repairs .................................................................................................................................4
2GETTING STARTED ............................................................................................................6
2.1 General Information..............................................................................................................6
2.2 Installing the Interface ..........................................................................................................6
2.2.1 Windows 98 Installation........................................................................................................6
2.2.2 Windows 2000/XP Installation...............................................................................................6
2.2.3 Linux Installation...................................................................................................................6
2.3 USB232U/485Ui Configuration Jumper Settings ...................................................................7
2.3.1 RS485 Full Duplex / Half Duplex Operation..........................................................................7
2.3.1.1 Jumper Selection For Full Duplex Operation ........................................................................7
2.3.1.2 Jumper Selection For Half Duplex Operation with Echo........................................................7
2.3.1.3 Jumper Selection For Half Duplex Operation without Echo...................................................7
2.3.2 Transmission Line Termination.............................................................................................8
2.3.2.1 Termination Resistors for RS422/485 Receivers...................................................................8
2.3.3 Jumper Factory Settings Summary.......................................................................................8
2.4 Application Software.............................................................................................................9
2.4.1 Installation Testing................................................................................................................9
3MAKING THE CONNECTIONS ..........................................................................................10
3.1 External Connections..........................................................................................................10
3.1.1 USB Connector...................................................................................................................10
3.1.2 RS232 9-way Port...............................................................................................................10
3.1.3 RS422/485 9-way Port........................................................................................................11
3.2 Connector Wiring for RS422/485 Full/Half Duplex ..............................................................11
3.3 The Ground Connections....................................................................................................11
3.3.1 USB232U Ground Connections ..........................................................................................11
3.3.2 USB485Ui Ground Connections..........................................................................................12
3.4 Choice of Cable..................................................................................................................12
4USING THE SERIAL COMMUNICATIONS DEVICES.........................................................13
4.1 Why Isolate? ......................................................................................................................13
4.2 Application Notes................................................................................................................14
4.2.1 Applicable Standards..........................................................................................................14
4.2.1.1 RS Standards .....................................................................................................................14
4.2.2 RS232 Application Notes....................................................................................................14
4.2.2.1 RS232 Electrical Levels......................................................................................................15
4.2.2.2 RS232 Data Rates and Cable lengths.................................................................................15
4.2.2.3 RS232 Cable Adapters .......................................................................................................15
4.2.3 RS422/485 Application Notes .............................................................................................15
4.2.3.1 RS422/485 Parameters ......................................................................................................16
4.2.3.2 RS422/485 Signalling Sense ..............................................................................................16

USB232U/485Ui
4.2.3.3 RS422/485 Multi-drop Applications.....................................................................................16
4.2.3.4 RS422/485 Bus Termination...............................................................................................17
4.2.3.5 RS422/485 Data Rates and Cable lengths..........................................................................18
4.2.3.6 Cabling of RS422/485 Bus..................................................................................................18
4.2.4 USB Application Notes .......................................................................................................18
4.2.4.1 Data Rates and Flow Control for USB to RS232 .................................................................18
4.3 Testing and Troubleshooting...............................................................................................19
4.3.1 Testing with the Application Software .................................................................................19
4.3.2 The Loop Back Connections ...............................................................................................20
4.3.3 Loop-back Testing Using A Terminal Emulator ...................................................................20
5PROGRAMMING................................................................................................................22
5.1 Programming with Windows 98, 2000 and XP Device drivers. ............................................22
5.2 Half Duplex Transmission Turnaround................................................................................22
APPENDIX A - TECHNICAL SPECIFICATIONS................................................................................. I
A.1 HARDWARE SPECIFICATION..............................................................................................i
A.1.1 USB.......................................................................................................................................i
A.1.1.1 Series B connector ................................................................................................................i
A.1.2 USB232U RS232 Port ..........................................................................................................ii
A.1.2.1 9-way Connector...................................................................................................................ii
A.1.2.2 Data Rate .............................................................................................................................ii
A.1.2.3 I/O Protection .......................................................................................................................ii
A.1.2.4 ESD Protection.....................................................................................................................ii
A.1.3 USB485Ui RS422/485 Port.................................................................................................. iii
A.1.3.1 9-way Connector..................................................................................................................iii
A.1.3.2 Data Rate ............................................................................................................................ iii
A.1.3.3 Rx I/P Termination ..............................................................................................................iii
A.1.3.4 Tx O/P Protection................................................................................................................ iii
A.1.3.5 I/O Isolation......................................................................................................................... iii
A.1.3.6 ESD Protection.................................................................................................................... iii
A.1.3.7 Modes .................................................................................................................................iii
A.1.3.8 Transmit Turnaround ........................................................................................................... iii
A.1.4 UART ..................................................................................................................................iv
A.1.4.1 Baud Rates..........................................................................................................................iv
A.1.4.2 Data Bits..............................................................................................................................iv
A.1.4.3 Stop Bits..............................................................................................................................iv
A.1.4.4 Parity...................................................................................................................................iv
A.1.5 PC INTERFACE ..................................................................................................................iv
A.1.5.1 Compatibility .......................................................................................................................iv
A.1.5.2 Host resources.....................................................................................................................iv
A.1.5.3 USB Frame Rate .................................................................................................................iv
A.1.5.4 USB packet size ..................................................................................................................iv
A.2 SOFTWARE........................................................................................................................iv
A.3 ENVIRONMENTAL CONDITIONS........................................................................................v
A.3.1 Specific conditions................................................................................................................v
A.3.1.1 Dimensions...........................................................................................................................v
A.3.1.2 Temperature Range..............................................................................................................v
A.3.1.3 Power Requirements ............................................................................................................v
A.3.1.4 Dissipation............................................................................................................................v

USB232U/485Ui
LIST OF FIGURES
Figure 2.1 Jumper Settings For Full Duplex Operation........................................................................7
Figure 2.2 Jumper settings for Half Duplex Operation with Echo.........................................................7
Figure 2.3 Jumper settings for Half Duplex Operation without Echo....................................................7
Figure 2.4 Jumper Settings for Termination Resistor Selection ...........................................................8
Figure 2.5 Factory Jumper Setting Summary......................................................................................8
Figure 3.1 USB Connector Termination Assignment .........................................................................10
Figure 3.2 RS232 9-way Port Pin Designations.................................................................................11
Figure 3.3 RS422/485 Amplicon Standard Port Pin Designations......................................................11
Figure 4.1 Communications Standards Summary .............................................................................16
Figure 4.2 RS422 Connected in Broadcast Mode..............................................................................17
Figure 4.3 RS485 Connected in Multi-Drop, Half Duplex Mode .........................................................17
Figure 4.4 RS232 Loop-Back Test Connections ................................................................................20
Figure 4.5 RS422/485 Loop-Back Test Connections .........................................................................20

USB232U/485Ui
Page 1
1 INTRODUCTION
The USB232 Universal (USB232U) and USB485 Universal isolated (USB485Ui) serial
communications interfaces are a range of USB peripherals that provide legacy RS232 or
RS485 serial communication interfaces to computers with USB support.
1.1 The Products Described in this Manual
There are two variants of USB232U/485Ui. Each supports a single serial communications
interface that appears to operating system as a standard serial port.
USB232U A non-isolated RS232 interface.
USB485Ui An isolated RS485 interface.
1.2 Features of the USB232U/485Ui Series of Data Communications Interfaces
Each of the USB232U/485Ui series of interfaces is designed to meet stringent performance
requirements and ease of use while maintaining compatibility with standard serial
communications products.
•USB 1.1 specification compliant
•Windows 98, 2000, XP and Linux compatible
•Data rates selectable up to 1 M Baud (RS232) and 3 M Baud (RS485)
•FIFO modes supporting a 384 character receive buffer and 128 byte transmit buffers
•Three point isolated serial communications on isolated versions
•Full Duplex, Half Duplex, Multi-drop applications
•RS485 transmitter can be enabled automatically in Half Duplex mode
•Full specification signal levels
•Implementation of all RS232 primary control lines
•Low power consumption

USB232U/485Ui
Page 2
1.3 General Description
The USB232U and USB485Ui are advanced RS232/RS485 serial communications interfaces
suitable for any IBM PC or compatible computer that supports USB 1.1.
All models are supported by third party Windows 98, 2000, XP and Linux drivers. Microsoft
Windows drivers are distributed on the CD that accompanies this product. The Linux drivers
are available as standard as part of the 2.4.0 kernel and above.
These drivers are a superset of the Microsoft serial drivers and allow the devices to operate as
standard serial ports. These drivers also allow the advanced features of the devices to be fully
utilised by the application software.
There are two models available in the range.
USB232U provides a 9-pin RS232 port
USB485Ui provides an isolated 9-pin RS422/485 port, jumper configurable for half-
duplex.
Each interface consists of a small unit which takes up to one USB unit load, 100mA, from the
PC USB interface. It connects to the USB interface via a standard USB interface cable and
one serial port designed to meet one of the following standards:
RS232 full duplex serial port furnished with a 9-pin D-type male connector conforming to IBM
practice. The port is fully configured with two data, six control I/O lines and one signal return.
RS485 full duplex, half-duplex, multi-drop operation or RS422 full duplex without RTS-CTS
control lines. Depending on the application, RS485 or RS422 operation is selected by making
the appropriate connections. Each RS422 / 485 port is furnished with a 9-pin D-type male
connector.
The RS485 ports have a link selectable “Half Duplex” mode that causes the transmit buffer to
be enabled automatically, by the UART, whenever data is waiting to be sent from the UART
Transmit buffer.
The USB485Ui is designed to isolate the serial communications from the computer power. The
design is such that it will sustain common mode voltages up to 75Vdc, which is outside of the
low voltage directive (73/23/EEC). However in fault conditions they are protected to sustain
common mode voltages up to peaks of 1 kVdc. It provides isolation of the data and can be
used in serial communications systems where high integrity data transmission and reception
are required in an electrically severe environment.

USB232U/485Ui
Page 3
1.3.1 Enhanced Features
The USB232U supports data rates up to 920k Baud. The USB485Ui supports data rates up to
3M Baud. There is a 384 byte receive FIFO buffer and 128 byte transmit FIFO buffer
associated with each port. This allows the processor to service the ports in a timely manner
over the USB bus.
If you have an RS485 Half Duplex or Multi-drop application. There is a link selectable Half-
Duplex mode. In this mode, the RS485 transmit buffer is enabled automatically by the UART,
whenever data is waiting to be sent in the UART Transmit buffer. This feature makes efficient
multi-drop communication simple to implement by removing the burden of the Transmit buffer
enable control from the software.
1.4 What the Package Contains
The package as delivered from Amplicon Liveline Ltd contains:
1. The USB serial interface as ordered, in a protective bag. The model will be one of the
following, and is identified by the type number printed on the PCB.
USB232U USB to RS232 Serial Communications Controller
USB485Ui USB to RS422/485 Serial Communications Controller with I/O signal
isolation
2. The included distribution software and this manual on CD
3. Any additional accessories (mating connectors, software etc.) may be packed separately.
1.4.1 The Amplicon Warranty Covering the USB232U/485Ui interfaces
This product is covered by the warranty as detailed in the Terms and Conditions stated in the
current domestic or international Amplicon Liveline Ltd catalogue and at our website at
http://www.amplicon.co.uk.
1.4.2 Contacting Amplicon Liveline Limited for Technical Support or Service
The USB Series of interfaces are designed and manufactured by Amplicon Liveline Ltd and
maintenance is available throughout the supported life of the product.

USB232U/485Ui
Page 4
1.4.3 Technical Support
Should the device appear defective, please check the information in this manual and any 'Help'
or 'READ.ME' files appropriate to the program in use to ensure that the product is being
correctly applied.
If an application problem persists, please request Technical Support in one of the following
ways:
Web: www.amplicon.co.uk
Email: [e-mail]
Telephone: UK 0906 293 0293
International [phone]
Calls cost 25p per min from a BT landline. Calls from other services may vary
Fax: UK 01273 570 215
International [phone]
It will assist the support engineer if you have the following information available when you call:
Your Amplicon account number or postcode
Date of purchase
The Operating System you are running under
The specification of your computer
The nature of your problem and the results of any tests you have
conducted.
You may also be asked if the operating system prompted you for a disk when you installed the
device.
1.4.4 Repairs
If the unit requires repair then please return the goods enclosing a repair order detailing the
nature of the fault. If the device is still under warranty, there will be no repair charge.
For traceability when processing returned goods, a Returned Materials Authorisation (RMA)
procedure is in operation. Before returning the goods, please request an individual RMA
number by contacting Amplicon Customer Services as detailed above. Please mark the RMA
number on the outside of the packaging to ensure that the package is accepted by the Goods
Inwards Department.
Give the reason for the return and, if the goods are still under warranty, the original invoice
number and date. Repair turnaround time is normally five working days but the Service
Engineers will always try to co-operate if there is a particular problem of time pressure.
Address repairs to:
Customer Services Department
AMPLICON LIVELINE LIMITED
Centenary Industrial Estate