Brainboxes CC-324, 1 Port PCI Velocity RS422, 1 Port PCI Velocity RS485 User Manual

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1.1 E D IT IO N JA N U AR Y 2000

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PCI VELOCITY R S 422/485 AUTOGATING

These products conform to the following standards:

CE standard: EN55022:1987 Class B
IEC 801-2: 1991 Level 2
IEC 801-3: 1984 Level 2
IEC 801-4: 1998 Level 2

PCB: IEC 249-2-5
NEMA L1 1-10
DIN 40802
UTE C 93-711
BS 4584
MIL P-13949E
UL Approved to 94 V0

TIA /EIA: 485 A (1995) ,423 B (1996)

Year 2000: DISC PD2000-1

PCI VELOCITY R S 422/485 AUTOGATING

OUTLINE CONTENTS

Chapter 1 - Supplied Serial Solution Software.
Chapter 2 - PCI Velocity RS422/485 Specifications.
Chapter 3 - PCI Velocity R S422/485 Software

Configuration Guide.

Chapter 4 - Additional RS422/RS485 Information.

The Layout Of This Manual

Chapter 1 - Serial Solution Software

,

is an overview of this

companion software package for our range of serial port cards.

Chapter 2 - PCI Velocity RS422/485 Specifications,

gives details of the PCI Velocity RS422/485 specifications and
shows you how to install your PCI Velocity RS422/485 card.

Chapter 3 - PCI Velocity RS422/485 Software
Configuration Guide

, shows you how to configure your
operating system to successfully allow trouble free operation of your
PCI Velocity RS422/485 card. Installation procedures are for DOS,
Windows 3.x, Windows 95, Windows 98/Millenium, Windows NT
and Windows 2000.

Chapter 4 - Additional RS422/RS485 Information

,

gives
details on the RS422 and R485 standard, and cabling; as well as
examining half and full duplex RS485 systems and information on
card grounding systems.

TABLE OF CONTENTS

CHAPTER 1 SERIAL SOLUTIONS SOFTWARE.....6

Introduction. .............................................................................. 6

Introducing Serial Solution Software. ....................................... 6

Serial Solutions For DOS.......................................................... 6

Serial Solutions For Windows 3.x.............................................. 8

Serial Solutions For Windows 9x............................................... 8

Serial Solutions For Windows NT. ............................................ 9

Complete Documentation and Technical Backup...................... 9

CHAPTER 2 P CI 1 PORT VELOCITY RS422/48

HARDWARE SETUP ....................................................10

Introduction. ............................................................................ 10

General PCI RS422/485 Card Features.................................. 10

General PCI RS422/485 Serial Port Features ........................ 11

Autogating................................................................................ 11

Configuring The PCI RS422/485 Cards................................. 13

Full Duplex Settings................................................................. 13

With Half Duplex Settings........................................................ 13

Hardware Installation.............................................................. 14

Problems!................................................................................. 15

CHAPTER 3 P CI 1 PORT VELOCITY RS422/485

SOFTWARE CONFIGURATION GUIDE..................16

I

NTRODUCTION

. ............................................................................ 16

DOS I

NSTALLATION

..................................................................... 16

Determining PCI RS422/485 Resources.................................. 16

NEWCOM.SYS Parameters. .................................................... 17

Configuring And Installing NEWCOM.SYS............................. 19

Modifying Command Line Parameters.................................... 20

W

INDOWS 3.X INSTALLATION

....................................................... 21

Determining PCI RS422/485 Resources.................................. 21

Windows 3.x Software Installation. ......................................... 22

Serial Port Installation. ........................................................... 23

Configuring The COM Ports. .................................................. 25

Deleting Ports in Windows...................................................... 26

Restarting Windows................................................................. 26

W

INDOWS

95 I

NSTALLATION

........................................................ 27

Card Settings In Windows 95................................................... 31

PCI RS422/485 Port Settings In Windows 95......................... 32

W

INDOWS

98/M

ILLENIUM INSTALLATION

.................................... 37

Card Settings In Windows 98/Millenium................................ 41

Port Settings In Windows 98/Millenium.................................. 42

W

INDOWS

NT 4.0 I

NSTALLATION

................................................. 47

Software Installation................................................................ 47

Examining Card Configuration............................................... 48

Configuring Ports.................................................................... 49

Advanced Port Settings............................................................ 50

Uninstalling Serial Solutions PCI............................................ 52

CHAPTER 4 ADDITIONAL RS422/485 OPERATION

...........................................................................................53

The RS422 Standard. ............................................................... 53

The RS485 Standard. ............................................................... 53

Terminating Impedance’s. ....................................................... 54

Fail Safe Open Circuit Detection............................................ 55

Fail Safe Short Circuit Protection........................................... 55

RS422 Operation...................................................................... 55

RS422 Serial Port Cables........................................................ 56

RS485 Operation...................................................................... 57

RS485 Cable. ........................................................................... 57

RS485 One Talker - Many Listeners, Half Duplex.................. 58

RS485 Many Talkers- Many Listeners, Half Duplex............... 59

RS485 Many Talkers- Many Listeners, Full Duplex................ 60

Optional Grounding Arrangements......................................... 61

INDEX..............................................................................64

PCI 1 Port RS422/485 Serial Solutions

Chapter 1 Page 6

Chapter 1

SERIAL SOLUTIONS SOFTWARE

Introduction.

This chapter is a brief description of the Serial Solutions
software package; this can also be purchased SEPARATELY and is
available from YOUR DEALER.

Introducing Serial Solution Software.

The perfect partner for any Serial Port is Serial Solutions
Software! Serial Solutions is a fully featured suite of programs
designed to squeeze the most from PC serial communications.

Serial Solutions is made up of the following components: -

Serial Solutions for DOS
Serial Solutions for Windows 3.x
Serial Solutions for Windows 95/98

Serial Solutions for Windows NT

All the Serial Solutions drivers have the following fea tures: -

• Drivers for PC FIFO UARTs e.g. 16550 as well as the new

improved 32 byte 16650 and 64 byte 16750 UARTs.

• Support for any mix of RS232, RS422, and RS485 handshake

schemes.

• Support for wider range of Baud rates and for more than 4 serial

ports.

Serial Solutions For DOS.

Serial Solutions for DOS consists of the following programs:

­NewCOM.sys A device driver, it supports COM1 to COM16,

allowing 16 serial ports to be used under DOS. It
also includes an interrupt handler for enhanced
performance with user definable buffer sizes.

PCI 1 Port RS422/485 Serial Solutions

Chapter 1 Page 7

Accessible from all DOS languages, it is the heart
of the Serial Solution.
It has extensive handshaking support,
implementing both hardware handshaking using
any combination of the DTR, DSR, CTS, RTS,
and DCD lines, and a software handshake using

the XON/XOFF protocol.
NewCOM24.sys A device driver providing support for 24 ports.
NewCOM32.sys A device driver providing support for 32 ports.
NewMode.exe A replacement for the DOS 'mode com...'

command. NewMode is used to set the serial

parameters, including the port address, IRQ line

used, the baud rate, parity and data and stop bit

options. Baud rates supported are from 110 baud

to 115,200 baud! Included is a very handy query

mode that reports the settings of the various serial

ports. Flexible and fast!
EASY programs. The EASY disk contains short, simple to

understand and use EASYBAS, EASYC and

ASYPAS programs, providing straight forward,

file type I/O to serial ports with debug

information. Use these FIRST, base your sample

applications on them. Source code, make files and

compiled ready to run programs supplied.
TERM programs A suite of larger terminal emulation programs

written in C (Cterm), Assembly language

(Aterm), Pascal (Pasterm), BASIC (BASterm)

and FORTRAN (FORterm) show how to access

the NEWBIOS routines as well as the simple file

I/O to ports. They contain many lines of code and

are thus harder to grasp. They demonstrate in

depth serial port programming in a variety of

languages but they are also useful tools for using

serial devices.
Comtest.exe Comtest is a short but invaluable program that is

used to check that the serial port at a particular I/O

address is functioning correctly and is connected to

PCI 1 Port RS422/485 Serial Solutions

Chapter 1 Page 8

the particular IRQ line. The program correctly

identifies the UART type by employing the built in

loop back capability of the PC serial port chip, a full

test of the baud rate generator, transmitting and

receiving buffer, parity enable and start stop bit is

performed. There is no need for a second serial port

or a cable when using this utility .

Serial Solutions For Windows 3.x

Serial Solutions for Windows 3.x works with Windows 3.0,

3.1 and 3.11 as well as Windows For Workgroups 3.11.

Serial Solutions for Windows 3.x consists of the following
programs: ­Setup.exe The install routine for the package.
Port.DLL Enhanced Control Panel applet. Allows

configuration of extra serial ports from the
Windows Control Panel. Supports single as well as

multiport cards using shared interrupts.
BbLynx.drv Replacement for COMM.DRV.
LynxAPI.dll Enhancement to the Windows Comms API's

allowing support for more than 9 ports.
Term.exe Terminal program.
EasyCWIN C source code, project files and ready to run.exe

program for an easy to understand Windows

terminal program. Learn how to write Windows

comms apps correctly the easy way.

Serial Solutions For Windows 9x.

Windows 95 has an improved communication API and
directly supports up to 255 ports. Our Windows 95 driver supports
the shared interrupt mechanism used on our multiport cards. Serial
Solutions for Windows 95 consists of the following programs: -

SSCards.inf The information file to aid the installation process

"Have Disk....”

Ssmodem.inf Setup file for Serial Solutions modems.

PCI 1 Port RS422/485 Serial Solutions

Chapter 1 Page 9

sscardui.dll
ssportui.dll The device manager configuration DLLs and…

ssenum.vxd
ssv485.vxd ...the virtual device drivers providing the shared
ssvel.vxd interrupt handlers and dispatch routines etc for the
ssmult.vxd various Serial Solutions serial cards.
ssm485.vxd

Serial Solutions For Windows NT.

Windows NT has an improved communication API and
directly supports up to 255 ports. No extra driver is necessary for
Windows NT to drive multiport cards. Serial Solutions for Windows
NT consists of the following programs: -

Setup.exe Expands into the Control Panel applet and associated

files which allows the configuration of all ports on
Serial Solutions serial cards.

Ssmodem.inf Setup file for Serial Solutions modems.

Complete Documentation and Technical Backup.

We believe in supplying complete documentation with every
package we sell. The Serial Solution Software Package is no
exception, it has an attractive manual in an A5 binder, containing
over 150 pages of in-depth technical detail with comprehensive
indexes and table of contents. We guarantee your Serial Solution
Software package for a full 12 months from purchase. A complete
technical backup service is available to ensure that you get the
maximum performance out of your investment.

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 10

Chapter 2

PCI 1 PORT VELOCITY RS422/48

HARDWARE SETUP

Introduction.

This chapter details the specifications of the PCI 1 Port
Velocity RS422/485 card and explains how to configure the RS485
Multiplex jumpers present on this card. This half-sized card will
work happily in any PCI 2.0 or greater compliant PC compatible.

General PCI RS422/485 Card Fe atures.

•

One 9 pin D RS422/485 serial port.

•

Reliable communications up to 4000 feet, 1.2 Kilometres.

•

16C750 FIFO provides 64-byte input and 64-byte output buffer

on each port.

•

Maximum baud rate of 921,600 Baud (1 Megabaud).

•

Word length of 5, 6, 7 or 8 bits.

•

Even, Odd, None, Mark or Space parity options.

•

1 start bit always sent.

•

1, (1.5 for 5-bit data word length), or 2 stop bits.

•

TXD, RXD, RTS, and CTS signals.

•

RS485 TXD/RXD multiplex selectable by jumpers: - either FULL
DUPLEX or HALF-DUPLEX

•

Autogating low level RS485 half duplex (2 wire) control

•

Fully double buffered for reliable asynchronous operation.

•

High-speed integrated circuitry ensures operation with fast PC's

e.g.700 MHz Pentium III WITHOUT extra wait states.

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 11

General PCI RS422/485 Serial Port Fe atures

Clock Input: 14.7456MHz
Drivers: SN75174
High Level Voltage: 3.7V typical at 33mA source
Low Level Voltage: 1.1V typical at 33mA source
High Level Current: -60mA max.
Low Level Current: 60mA max.
Receivers: SN75175.
Difftial I/P threshold: 200mV max.
Hysteresis: 50mVolt typical.
Input Impedance: >12K Ohm without terminators.

Autogating.

Multitasking operating systems, like Windows 95, Windows
NT, OS/2 and UNIX, cannot successfully use the RTS line to control
the gating of the PC’s transmitter. Whilst they can set the RTS line
true just before the data transmission starts, they cannot set the RTS
line false quickly enough after the data has gone. This is due to the
time slicing mechanism used by these multitasking operating
systems. The interrupt service routines in multitasking OS’s have a
long latency, i.e. time taken to switch context from the foreground
program to the interrupt routine. During this time, the first few bytes
of the external devices reply to the PC may be lost since the serial
port transmitter is still gated onto the twisted pair cable.

To overcome this problem, Autogating hardware has been
added to the to the RS422/485 card. This automatically detects the
start of the PC’s data transmissions, and gates the PC’s transmitter
onto the twisted pair cable. It then automatically detects the last stop
bit being sent and gates the port off the twisted pair cable. An added
bonus of

RS485 AUTOGATING

is that special device drivers no
longer need to be written to use RS485 in any operating system. To
all intents and purposes, it looks just like an ordinary RS232 COM
port to the host PC. Autogating for half duplex operation is a
necessity for Windows 95, NT and the forthcoming Windows 98
(Memphis) and Windows NT 5.

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 12

Figure 2-1. PCI 1PORT VELOCITY RS422/485
Layout.

RS485 Multiplex jumper block

PCI 1 PORT VELOCITYRS422/485 Specifications:

Dimensions: 4.8 x 2.5 in, 122 x 63.5 mm
I/O Connection: Serial Port 1: 9 pin Male D type.
Weight: 90g

Figure 2-3. 9 Pin D Connector Port Pinouts.

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TX/
RX1-

TX/
RX1+

MULTIPLEX

RS485

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 13

Configuring The PCI RS422/485 Cards.

PCI cards require no hardware configuration for IRQ and
address allocation - this is done automatically at start up by the PC.
However, the PC 1 Port Velocity RS422/485 has a set of jumpers for
configuration of RS485 multiplex modes, details of configuring
these jumpers is shown below.

Full Duplex Settings.

•

Both jumpers left unconnected (not shorted).

With Half Duplex Settings.

•

Both jumpers shorted, causing the RXD- & TXD- and the

RXD+ & TXD+ signals to short together at the 9-pin

connector. The multiplex jumpers should only be set for

RS485 Half Duplex operation, when one twisted pair is used

to interconnect both transmit and receive lines.

NOTE

: Any changes to RS485 Multiplex Operation must be
accompanied with appropriate changes to the driver software; see
Chapter 3 -

"PCI 1 Port VelocityRS422/485 Software

Configuration"

for more details.

For further details on the RS422 and RS485 standard, pinouts, half
duplex and full duplex RS485 systems, wiring diagrams and optional
grounding diagrams refer to Chapter 4 - "

Optional RS422/485

Operation

."

TX/RX1­TX/RX1+

MULTIPLEX

RS485

TX/RX1­TX/RX1+

MULTIPLEX

RS485

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 14

Hardware Installation.

STEP 1: Before the PC card can be installed the power to the PC

MUST

be switched

OFF

, and to ensure extra safety, the power lead

removed from the PC.

STEP 2: Remove the PC case.

Step 3 - Removing Blanking Cover

Step 4 - Inserting The PCI Serial Card.

STEP 5: The connectors should fit neatly through the slot's aperture
to the outside world.

STEP 6: Now replace the system unit's cover by carefully sliding it

C

hoose an empty expansion slot. Remove

t

he blanking cover protecting the slot on

t

he PC back panel. KEEP the blanking

c

over screw safely for later.

N

ow insert the PCI Serial card in the slot.

B

e careful to ensure that the gold plated

P

CB fingers fits neatly into the expansion

c

onnector. Press down firmly but evenly

o

n the top of the PCI Serial card

PCI 1 Port RS422/485 Hardware Setup

Chapter 2 Page 15

down and back over the system unit. Replace the cover mounting
screws.

STEP 7: After attaching all the monitor and keyboard cables, power
up the PC. Do not forget the mains power cable! The PC should then
power on in the normal way.

Problems!

If the system fails to power up normally, check the following:

i.) Ensure that the PCI Serial card is installed correctly.
ii.) Ensure that other cards in the PC have not been upset.
iii.) Ensure that the power is connected and the PC is switched ON!

If all these have been checked and the PC still does not power
up then inspect the area surrounding the card to ensure that any
potentially harmful bits of metal etc. are not present, if the problem
persists ask your dealer to check t he card or contact the HELP line as
given on Intro. Page 2.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 16

Chapter 3

PCI 1 PORT VELOCITY RS422/485

SOFTWARE CONFIGURATION

GUIDE

Introduction.

This section contains the installation procedures of the PCI
VELOCITY RS422/485 card, with the DOS, Windows 3.x
Windows 95, Windows 98/Millennium, Windows NT and
Windows 2000 operating systems.

The setup procedures in this chapter assume that your PC
has only one serial port present.

DOS Installation.

The DOS installation procedure consists of two steps after
the PCI RS422/485 card is inserted:

1. Determining the resources that the PCI RS422/485 has claimed.

2. Informing the Serial Solutions DOS device driver of those

resources.

Determining PCI RS422/485 Resources.

• Insert card into PC, as described in Chapter 2.

• Run BBCARDS.EXE, from the supplied Serial Solutions

CDROM by typing the following:

D:\diskimg\ssutil\pci\BBCARDS

Where D:\ is the Letter of your CDROM drive

BBCARDS.EXE will return a string that looks similar to
the following (values contained in the string may differ in
individual PC's due to resource availability):

card 1 is on bus 0, device 16, function 0
Card ID=5, revision 2: 1 Port Velocity RS422/485

interrupt line 11

has been assigned

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 17

1 set of 16550-compatible registers are at I/O address 0140
Baud clock control is at I/O address 02d0
Write 0xf6 for /8 (default), 0xf2 for /4, 0xd6 for /2, 0xd2 for /1.

• Note down IRQ and I/O which in this case:

The IRQ = 11

The I/O address = 0140

NEWCOM.SYS Parameters.

The NewCOM.SYS device driver included with the PCI
RS422/485 driver software is used to set up the card in DOS and
has the following syntax:

NEWCOM.SYS /A port address, /I IRQ,range /B number buffer
/S buffer /H hardware handshake

Where /A port address specifies COM port number followed by a

hexadecimal address in the form /Ax,y where x is COM

port range and y is I/O address.

/I IRQ, range specifies card interrupt and COM port range. The

COM port range specifies the COM port(s). Range may be a

single port OR a range of ports.

/B number buffer is used to set the number of pairs of

buffers to be allocated to ports and is a decimal number in

the range 1-maxport.

/S buffer Set size of all buffers in bytes, buffer is rounded

to the nearest power of 2 and must be a decimal number in

the range 32 to 32768. For any serial port opened two

buffers of size buffer are allocated, one for input and the

other for output.

/H hardware handshake selects which hardware handshake

type to use on the specified ports. This is used in the

following manner: /H range, hs where range specifies the

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 18

COM port or ports and hs selects handshake type.

Handshake types available are:

Type 1 RS422 RTS/CTS - The PC only transmits when

CTS is input true. When the PC is able to receive
its sets RTS output true. The DSR and DCD
inputs are ignored. The DTR output line is set
true just in case the ex ternal seri al device needs a
true signal.

Type 2 RS485 Half duplex - Before any data is sent the

PC sets RTS true, after the last byte in the buffer
has been sent the PC sets RTS false. RTS is used
as a transmit gating control. The CTS, DSR and
DCD inputs are ignored. The DTR output line is
set true just in case the external serial device
needs a true signal.

Type 3 RS485 Send only - This is a half duplex, transmit

only handshake. The PC transmits whenever it
wishes, it cannot receive any data. The CTS,
DSR and DCD inputs are ignored. The RTS
output line is set true just in case the external
serial device needs a true signal.

Type 4 3 Wire Handshake - Really no handshake at all

since the PC transmits irrespective of the
handshake lines. The 3 wires are TxD, RxD and
Ground, no other lines are required. Thus the
CTS, DSR and DCD inputs are ignored. The RTS
and DTR output lines are set true just in case the
external serial device needs a true signal.

Note:

If hardware handshaking is not specified in the

NEWCOM.SYS parameters, type 4, 3 Wire
Handshake is selected automa tica lly.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 19

Configuring And Installing NEWCOM.SYS

To load the Serial Solut ions for DOS device driver an entry
needs to be added to the CONFIG.SYS file. Any simple text editor,
EDIT for example, can edit the CONFIG.SYS file for example. The
installation procedure given below is for a PCI RS422/485 as COM

5.

The parameter required by the NEWCOM.SYS driver are
those returned by the BBCARDS.EXE application earlier. A brief
explanation for the parameters required by NEWCOM.SYS follows:

Port Address.

/A5,0140

COM port 5 is defined with an i/o address of 0140h.

IRQ, Range.

/I 11,5

11 is the IRQ and since the COM port is COM5 is entered 5.

Number Buffer.

/B5

Five buffers are defined, though only Three ports are in use

- this is because buffers in DOS are assigned in a sequenti al order
from COM1. Since the PCI Velocity RS422/485 has been assigned
a COM port value of 5, all preceding COM ports, must have
buffers assigned to them also.

Buffer Size.

/S512

Buffer size set to 512 bytes.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 20

Hardware Handshaking.

/H,4

Type 4, 3 Wire Handshake selected for all ports. Type 4, 3
Wire Handshake selected for all ports.

Modifying Command Line Param e ters.

When "assembled" the NEWCOM.SYS command line
looks like…

DEVICE=NEWCOM.SYS /A5,0140 /I 11,5 /B5 /S 512 /H,4

…and should be entered into the CONFIG.SYS file. Once you are
sure that these parameters have been entered correctly, restart your
PC and your PCI RS422/485 should be ready to use immediately.
Sample terminal applications are provided on "Serial Solutions
CDROM” enabling communications to be established to your
peripherals quickly and easily.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 21

Windows 3.x Installation.

The Windows 3.x installation procedure consists of two steps after
the PCI RS422/485 card is inserted:

1. Determining the resources that the PCI RS422/485 card has

claimed.

2. Informing Windows 3.x of those resources.

Determining PCI RS422/485 Resources.

• Insert the card into a PC, as described in Chapter 2.

• Run BBCARDS.EXE, from the supplied “Serial Solutions

CDROM” by typing the following:

D:\diskimg\ssutil\pci\BBCARDS

Where D:\ is the Letter of your CDROM drive

BBCARDS.EXE will return a string that looks similar to
the following (values contained in the string may differ in
individual PC's due to resource availability):

card 1 is on bus 0, device 16, function 0
Card ID=5, revision 2: 1 Port Velocity RS422/485

interrupt line 11

has been assigned

1 set of 16550-compatible registers

are at

I/O address 0140

Baud clock control is at I/O address 02d0
Write 0xf6 for /8 (default), 0xf2 for /4, 0xd6 for /2, 0xd2 for /1.

• Note down IRQ and I/O which in this case:

The IRQ = 11

The I/O address = 0140

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 22

Windows 3.x Software Installation.

Place the supplied Serial Solutions CDROM in a suitable
drive. From File Manager choose ‘Run’ and enter
D:\diskimg\sswin3x\setup (where D: is the path to the
CDROM drive Containing the disk).

• Click OK, the Setup Program Main Screen is displayed:

By default, all component options will be installed,
selecting the "Del All" button will select all installed components
for deletion and "Add All" chooses all uninstalled components for
installation; options may not be changed when the components are
installed. For further details on the Component Options consult the
README.TXT file on the supplied disk.

If only logical ports COM1 to COM9 are to be used then
de-select the Comms API library option in the "Install" column.
This library is only necessary to allow the use of logical ports
greater than COM9 e.g. COM10, COM11 etc.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 23

• When you have made your choice of Component Options click

Continue

and when the setup program has finished select the

Done

button.

Note:

If the Serial Port driver options has been selected, after the
setup program has finished, Windows will display a restart
message - answer

Yes

and Serial Solutions will be ready to run

upon Windows restarting.

Serial Port Installation.

• From

Main

, select

Control Panel

:

• Click on

Serial Ports

:

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 24

The following dialogue will be displayed:

To add a COM port:

• Click on the

add

button and a Window similar to the following

will be displayed:

• In

Standard Settings

:

• In the COM Base field, enter the value 0140.

Note:

COM ports are defined with an i/o address range,
which in this case, begins at 0140 and all subsequent
ports have an i/o address that is 8 higher than the
previous.

i.e.

if COM2 has an address of 0140h, then

COM3 has an address of 0148h.

• In the IRQ field, enter the value 11.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 25

Note

: The values used in the above section were those
returned by the BBCARDS program, as described in the
above section.
When you have finished, click on

OK

. A restart message
will be displayed; to save time only restart when both ports
have been added and correctly configured.

• After adding the COM port the COM Ports Window will look

similar to the following:

Configuring The COM Ports.

• From the COM Ports window choose the port that you wish to

configure and click on

Settings -

the following dialogue will

be displayed:

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 26

Note

: A port that has been added has the default values of:

Baud Rate: 9600
Data Bits: 8
Parity: None
top Bits: 1.0
Flow: None

Change the communications Settings in the COM Ports to

match the baud rate, parity settings etc. of the remote serial device.

Deleting Ports in Windows.

The

Delete

button can be used to discard the entries of

ports that have been removed from the system.

Note. Never try to leave out a serial port number when

using the delete button, because Windows may automatically shift
serial port numbers which results in a mis-match of settings in the
Serial Ports Applet (COM1-COM4 only).

Restarting Windows.

Whenever certain values have been entered or changed in

the hardware settings window, a message prompting to restart
Windows will appear. Only after having made ALL the necessary
changes restart Windows so that the new settings come into effect.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 27

Windows 95 Installation.

To obtain a trouble free mix-and-match of the COM ports:

• Switch off your computer, insert your PCI RS422/485 card into

a free PCI slot, as described in the section "

Hardware

Installation

" in Chapter 2, and switch your computer on again.

• During the booting process, Windows 95 will detect the PCI

Velocity RS422/485, but will display it simply as a "PCI
CARD", and you will briefly see a message box to this effect.

• Windows will then display the "Update Device Driver Wizard",

which asks you to “insert any disk which came with the PCI
card”. Insert the Serial Solutions CD ROM into an appropriate
drive and click 'Next'.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 28

• The Wizard should then display the following:

• Click

Other Locations

• In the location space type

<drive>:\diskimg\sswin9x

where

drive is the appropriate letter for your CDROM drive

• Click

OK

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 29

• Click

Finish

• After copying the file, Windows 95 will then detect each of the

serial ports in turn and install them as communications ports.

• Using the right-hand mouse button click on the

My Computer

icon on your desktop. Click on

Properties.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 30

• Click on the

Device Manager

tab

When the "

Device Manager

" is viewed the PCI 1 port

Velocity R422/485 card will appear under the "

Multi-function

adapters

" branch. Also, a Velocity RS485 Port will appear under

the "

Ports (COM & LPT) branch

".

For most users who have 4 or less COM ports the new port

will appear as COM5 as pictured above, for users with more than 5
COM ports the new port will appear as the first available COM
ports.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 31

Card Settings In Windows 95

• Select the PCI Velocity RS422/485 card from the "

Multi-

Function Adapter

" entry in

Device Manager

serial and click

on properties to view the cards general properties.

• Click on the

Serial Solutions

tab Solutions tab produces.

The I/O address and interrupt
are assigned to the card by the
"Plug and play" system of the
PC. These values CANNOT
be changed with the current
version of the driver.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 32

In this window, the COM port assignment may be changed, simply
by selecting a new COM port value from the pull down menu
relevant to the port. However, COM port usage other than those
for the PCI 1 Port Velocity RS422/485 card itself are not checked,
so it is advisable to first check which COM ports are in use - port
availability can be checked by viewing the

Device Manager

:

All COM ports present will be listed under the entry "

Ports

(COM & LPT)

." The above screenshots indicates that COM2 - 4

and COM6 and above are not installed, and therefore may be used.

PCI RS422/485 Port Settings In Windows 95.

Double clicking on a Velocity RS485 Port entry from the

entry "

Ports (Com & LPT)

" branch in

Device Manager

will the
display general properties window for the selected port (in this
case COM5).

•

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 33

Selecting the Port Settings tab produces:

Settings available in this window are:

1.

Baud Rate

- determines the baud rate at which the
selected port operates, the maximum value available is
dependant upon the Maximum Baud Rate Setting (see
below.)

2.

Data Bits.

3.

Parity.

4.

Stop Bits.

5.

Flow Control.

6.

Maximum Baud Rate Setting

- four values are
available, which selects the maximum baud rate at
which the port may operate. The table below, indicates
the ranges of baud rate values available at the
Maximum Baud Rate Settings.

C

hange to suit remote device.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 34

Maximum Baud Rate Settings.

Maximum Baud Rate

115200 230400 460800 921600

50 100 200 400
75 150 300 600

110 220 440 880
150 300 600 1200
300 600 1200 2400

600 1200 2400 4800
1200 2400 4800 9600
1800 3600 7200 1440
2000 4000 8000 16000
2400 4800 9600 19200
3600 7200 14400 28800
4800 9600 19200 38400
7200 14400 28800 57600
9600 19200 38400 76800

19200 38400 76800 153600
38400 76800 153600 230400
57600 115200 230400 460800

115200 230400 460800 921600

Note

: Many serial comms applications will not actually

register the ports as running at baud rates of above 115200.

7.

Restore Defaults

- when clicked, resets the selected
COM port to the following values:
Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 35

• Clicking on the Serial Solutions tab will display:

Settings available in this window are:

1.

FIFO Settings.

•

Enab le FIFO

- turns the selected ports FIFO buffer
on or off. It is strongly recommended that the FIFO
for both ports is left enabled.

•

Exten d FI FO

- when checked, extends the selected

ports FIFO buffer from 16 to 64 bytes.

•

Receive Buffer

- These settings allow the selection
of a receiver FIFO trigger setting. Selecting a low
value will allow the interrupt to be serviced quicker,
which is good for slow machines. If you have a fast
machine, setting a high value will give you more
time for multi-tasking operations.

•

Transmit Buffer

- These settings allow the selection
of a transmitter FIFO trigger setting. Selecting a low
value will send fewer data-bytes per interrupt, and
this is recommended if you are communicating to a
slower machine. Selecting a high value will send
more data-bytes per interrupt, and will give more
time for multi-tasking operations.

2.

Automatic Hardware Flow Control

. One of two

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 36

options may be selected:

•

Off

(Default) - This will turn off automatic flow
control. (If you have no data transfer problems then
selecting this option is fine.)

•

RTS/CTS

- This will use the RTS and CTS lines

for automatic hardware flow control.

3.

485 Mode

offers the options:

•

Half Duplex

/

Full Duplex

(default) - are used in
conjunction with the RS485 Multiplex Jumper
Settings.

NOTE

: These software settings must match the
RS485 Multiplex Jumper configuration, as
described in the section "

RS485 Multiplex Jumper

Settings

" in Chapter 2, to ensure accurate and error

free data transmission.

•

CTS Hold True,

determines whether the CTS
handshake signal is INPUT from the external serial
device or is permanently forced true on the card.
The serial ports own RTS OUTPUT handshake
signals are always taken out to the serial port
connector.

4.

Restore

- when this button is clicked the settings in the
current window will be reset to the default values of:
Enable FIFO: On (Checked)
Extend FIFO: Off (Unchecked)
Receive Buffer: 3rd from left.
Transmit Buffer: 16
Automatic Hardware
flow Control: Off
485 Mode: Full duplex.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 37

Windows 98/Millenium Installation.

To obtain a trouble free mix-and-match of the COM ports:

• Switch off your computer, insert your PCI RS422/485 card into

a free PCI slot, as described in the section "

Hardware

Installation

" in Chapter 2, and switch your computer on again.

• During the booting process, Windows 98 will detect the PCI

Velocity RS422/485, but will display it simply as a "PCI
CARD", and you will briefly see a message box to this effect.

• Windows will then display the "Update Device Driver Wizard",

which asks you to “insert any disk which came with the PCI
card”. Insert the Serial Solutions CD ROM into an appropriate
drive and click 'Next'.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 38

• The Wizard should then display the following:

• Select

Search for the best driver for your device.

• Click

Next

• Click

Specify a location

• In the location space type

<drive>:\diskimg\sswin9x

where

drive is the appropriate letter for your CDROM drive

• Click

Next

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 39

• Click

Next

• Click

Finish

• After copying the file, Windows 95 will then detect each of the

serial ports in turn and install them as communications ports.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 40

• Using the right-hand mouse button click on the

My Computer

icon on your desktop. Click on

Properties.

• Click on the

Device Manager

tab

When the "

Device Manager

" is viewed the PCI 1 port Velocity

R422/485 card will appear under the "

Multi-function adapters

"

branch. Also, a Velocity RS485 Port will appear under the "

Ports

(COM & LPT) branch

".

For most users who have 4 or less COM ports the new port
will appear as COM5 as pictured above, for users with more than 5
COM ports the new port will appear as the first available COM
ports.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 41

Card Settings In Windows 98/Millenium.

• Select the PCI Velocity RS422/485 card from the "

Multi-

Function Adapter

" entry in

Device Manager

serial and click

on properties to view the cards general properties.

• Click on the

Serial Solutions

tab Solutions tab produces.

The I/O address and interrupt
are assigned to the card by the
"Plug and play" system of the
PC. These values CANNOT
be changed with the current
version of the driver.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 42

In this window, the COM port assignment may be changed, simply
by selecting a new COM port value from the pull down menu
relevant to the port. However, COM port usage other than those
for the PCI 1 Port Velocity RS422/485 card itself are not checked,
so it is advisable to first check which COM ports are in use - port
availability can be checked by viewing the

Device Manager

:

All COM ports present will be listed under the entry "

Ports

(COM & LPT)

." The above screenshots indicates that COM2 - 4

and COM6 and above are not installed, and therefore may be used.

Port Settings In Windows 98/Millenium.

Double clicking on a Velocity RS485 Port entry from the
entry "

Ports (Com & LPT)

" branch in

Device Manager

will the
display general properties window for the selected port (in this
case COM5).

•

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 43

Selecting the Port Settings tab produces:

Settings available in this window are:

8.

Baud Rate

- determines the baud rate at which the
selected port operates, the maximum value available is
dependant upon the Maximum Baud Rate Setting (see
below.)

9.

Data Bits.

10.

Parity.

11.

Stop Bits.

12.

Flow Control.

13.

Maximum Baud Rate Setting

- four values are
available, which selects the maximum baud rate at
which the port may operate. The table below, indicates
the ranges of baud rate values available at the
Maximum Baud Rate Settings.

C

hange to suit remote device.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 44

Maximum Baud Rate Settings.

Maximum Baud Rate

115200 230400 460800 921600

50 100 200 400
75 150 300 600

110 220 440 880
150 300 600 1200
300 600 1200 2400

600 1200 2400 4800
1200 2400 4800 9600
1800 3600 7200 1440
2000 4000 8000 16000
2400 4800 9600 19200
3600 7200 14400 28800
4800 9600 19200 38400
7200 14400 28800 57600
9600 19200 38400 76800

19200 38400 76800 153600
38400 76800 153600 230400
57600 115200 230400 460800

115200 230400 460800 921600

Note

: Many serial comms applications will not actually

register the ports as running at baud rates of above 115200.

14.

Restore Defaults

- when clicked, resets the selected
COM port to the following values:
Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 45

• Clicking on the Serial Solutions tab will display:

Settings available in this window are:

5.

FIFO Settings.

•

Enab le FIFO

- turns the selected ports FIFO buffer
on or off. It is strongly recommended that the FIFO
for both ports is left enabled.

•

Exten d FI FO

- when checked, extends the selected

ports FIFO buffer from 16 to 64 bytes.

•

Receive Buffer

- These settings allow the selection
of a receiver FIFO trigger setting. Selecting a low
value will allow the interrupt to be serviced quicker,
which is good for slow machines. If you have a fast
machine, setting a high value will give you more
time for multi-tasking operations.

•

Transmit Buffer

- These settings allow the selection
of a transmitter FIFO trigger setting. Selecting a low
value will send fewer data-bytes per interrupt, and
this is recommended if you are communicating to a
slower machine. Selecting a high value will send
more data-bytes per interrupt, and will give more
time for multi-tasking operations.

6.

Automatic Hardware Flow Control

. One of two

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 46

options may be selected:

•

Off

(Default) - This will turn off automatic flow
control. (If you have no data transfer problems then
selecting this option is fine.)

•

RTS/CTS

- This will use the RTS and CTS lines

for automatic hardware flow control.

7.

485 Mode

offers the options:

•

Half Duplex

/

Full Duplex

(default) - are used in
conjunction with the RS485 Multiplex Jumper
Settings.

NOTE

: These software settings must match the
RS485 Multiplex Jumper configuration, as
described in the section "

RS485 Multiplex Jumper

Settings

" in Chapter 2, to ensure accurate and error

free data transmission.

•

CTS Hold True,

determines whether the CTS
handshake signal is INPUT from the external serial
device or is permanently forced true on the card.
The serial ports own RTS OUTPUT handshake
signals are always taken out to the serial port
connector.

8.

Restore

- when this button is clicked the settings in the
current window will be reset to the default values of:
Enable FIFO: On (Checked)
Extend FIFO: Off (Unchecked)
Receive Buffer: 3rd from left.
Transmit Buffer: 16
Automatic Hardware
flow Control: Off
485 Mode: Full duplex.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 47

Windows NT 4.0 Installation.

Microsoft Windows NT Provides built in support for 255
standard serial ports. To setup your PCI RS422/485 serial card you
should follow these steps. Please note that to change any kind of
hardware configuration under Windows NT you must be logged in
as a user with Administrator level privileges, if you do not have
these please contact your system administrator.

Software Installation.

Insert the PCI 1 Port Velocity RS422/485 into your PC, as
described in chapter 2, and restart. Place the supplied CDROM
titled "Serial Solutions Software" in a suitable drive and from the
Start Menu choose Run and enter
<drive>:\diskimg\ssnt\setup (where <drive>: is the
path to the CDROM drive containing the installation disk).

• InstallShield will then install the driver software automatically -

it will then copy the necessary files and start itself. This
automatically detects your new PCI serial card(s) and does not
require any further system restarting.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 48

Examining Card Configuration.

Go to Control Panel (Start/Settings/Control Panel) and
double click on Serial Solutions PCI:

You will be presented with a Serial Solutions PCI Port
Configuration window:

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 49

Configuring Ports.

To view the settings of a port, select it and click on
settings, and then click on the resources tab:

Settings available in this window are:

Settings available in this window are:

1.

Baud Rate

- determines the baud rate at which the
selected port operates, the max imum value available is
921,600 (1 Megabaud.)

Note

: Many serial comms
applications will not actually register the ports as
running at baud rates of above 115200.

2.

Data Bits.

3.

Parity.

4.

Stop Bits.

5.

Flow Control.

6.

Advanced

- see the section below, titled "Advanced

Port Settings."

C

hange to suit remote device.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 50

7.

Restore Defaults -

when clicked, resets the selected

COM port to the following values:

Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: Hardware

Advanced Port Settings.

When the

Advanced

button of Port Settings is selected the

following dialogue is displayed:

Settings available in this window are:

1. FIFO settings.

•

Use FIFO Buffers

- turns the selected ports FIFO
buffer on or off. It is strongly recommended that the
FIFO for both ports is left enabled.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 51

•

Receive Buffer

- These settings allow the selection
of a receiver FIFO trigger setting. Selecting a low
value will allow the interrupt to be serviced quicker,
which is good for slow machines. If you have a fast
machine, setting a high value will give you more
time for multi-tasking operations.

•

Transmit Buffer

- These settings allow the
selection of a transmitter FIFO trigger setting.
Selecting a low value will send fewer data-bytes per
interrupt, and this is recommended if you are
communicating to a slower machine. Selecting a
high value will send more data-bytes per interrupt,
and will give more time for multi-tasking
operations.

•

Use Extended FIFO Buffers

- when checked,
extends the selected ports FIFO buffer from 16 to
64 bytes.

2.

Automatic Hardware Flow Control

. One of three

options may be selected:

•

Off

(Default) - This will turn off automatic flow
control. (If you have no data transfer problems then
selecting this option is fine.)

•

RTS/CTS

- This will use the RTS and CTS lines

for automatic hardware flow control.

3.

485 Mode

offers the options:

•

Half Duplex

/

Full Duplex

(default) - are used in
conjunction with the RS485 Multiplex Jumper
Settings.

NOTE

: These software settings must match the
RS485 Multiplex Jumper configuration, as
described in the section "

RS485 Multiplex Jumper

Settings

" in Chapter 2, to ensure accurate and error

free data transmission.

PCI 1 Port RS422/485 Softw are Setup

Chapter 3 Page 52

•

Force CTS True,

determines whether the CTS
handshake signal is INPUT from the external serial
device or is permanently forced true on the card.
The serial ports own RTS OUTPUT handshake
signals are always taken out to the serial port
connector.

4.

Defaults -

When clicked this button resets the

advanced properties to the followed settings:

Use FIFO Buffers: On (checked)
Transmit Buffers: 1
Receive Buffers: 8
Use Extended FIFO: Off (Unchecked)
Automatic Hardware
Flow Control: Off
485 Mode: Full Duplex

Uninstalling Serial Solutions PCI.

To uninstall Serial Solutions PCI:

• From Control Panel, open the Add/Remove Programs applet,

then close the Control Panel.

• Select from the list Serial Solutions PCI.

• Click the Add/Remove button.

Windows NT will then uninstall the Serial Solutions PCI applet
without the need for restarting.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 53

Chapter 4

ADDITIONAL RS422/485

OPERATION

The RS422 Standard.

The RS422 standard defines a serial communications
standard. RS422 is a high speed and/or long distance data
transmission. Each signal is carried by a pair of wires and is thus a
differential data transmission system. Over distances up to 40 feet
the maximum data rate is 10 Megabits per second, and for
distances up to 4000 feet the maximum data rate is 100 Kilobytes
per second. A 120-Ohm resistor should be used to terminate the
receiving end of the line. It is generally used between one
transmitter receiver pair to ONLY one other transmitter receiver
pair, but each output can drive up to 10 receivers.

RS422 Standard

1 Driver up to 10 Receivers

Line Length Max Data Rate

40 Feet = 12m 10 Mbits/sec

400 Feet = 122m 1 Mbits/sec

4000 Feet = 1219m 100 Kbits/sec

'

5

77/ 77/

The RS485 Standard.

The RS485 standard is similar to the RS422 standard upon
which it is based. The main difference is that up to 32 transmitter
receiver pairs may be present on the line at one time. A 120-Ohm
resistor should be used to terminate either end of the main line. If

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 54

more than one device may transmit data, the RTS line is used as
transmit enable signal, so preventing contention between talkers.

RS485 Standard

Up to 32 Driver/Receiver Pairs

Line Length Max Data Rate

40 Feet = 12m 10 Mbits/sec

400 Feet = 122m 1 Mbits/sec

4000 Feet = 1219m 100 Kbits/sec

''

5

5

5

Terminating Impedance’s.

RS422 and RS485 lines should be terminated at the end of
the main branch of the RECEIVER, in the cables characteristic
impedance. These terminating impedance’s stop echoes caused by
the serial data being reflected back at the cable ends. It is not
necessary to terminate the transmitter end of the twisted pair.

The AT Dual Port RS422/485, Opto Isolated AT Dual Port
RS422/485 and AT Velocity RS422/485 cards have the correct
120 Ohm (nominal) terminating resistors for the RXD twisted pair
line and the CTS twisted pair line fitted on the RS422/485 card for
both the serial ports on the card.

There is no need to add any more at the PC end.

The terminating impedance’s shown later in the wiring
diagrams of Figure 4-1, Figure 4-2, Figure 4-4 & Figure 4-6 are
automatically provided by the on board resistors and do not have
to be added by the user.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 55

Fail Safe Open Circuit Detection

.

Open circuit is when there are no drivers on the circuit.
This occurs by design in party line multi driver/receiver systems
and unintentionally when the t wist ed pair li ne is acci dental ly cut or
disconnected or the transmitting device fails. In RS485 party line
systems there are extended periods of time when none of the many
possible talkers are gated onto the bus. This is known as the line
idle state and occurs when all the driver outputs are in the high
impedance state. The lines float, perhaps being pulled to the high
or low state by noise or other voltages on the line.

Without fail safe open circuit detection false start bits are
detected by the receivers, either corrupting good communications
or causing noise to masquerade as good data.

The on board fail safe open circuit detection causes the
receiver to go to a known, pre-determined state and prevents false
start bits and bad data being detected during open circuits.

Fail Safe Short Circuit Protection.

Short circuits are when the two lines of a twisted pair are
connected together. This occurs due to either accidental damage to
the cable or due to failure of one or more transmitter/receivers on
the line. The short circuit condition is dangerous since damage to
the receiver may occur and communication may be corrupted or
prevented.
The on board fail safe short circuit detection prevents the line
impedance from going to zero and thus protects the inputs of
receivers and the outputs of drivers.

RS422 Operation.

Generally, in RS422 systems all 8 signal lines from the 9
pin D connector participate in the data transfer sequence, thus 4
twisted pair cables are used. One twisted pair carries the TXD data
outwards, one pair brings the RXD data inward, another pair
carries the RTS handshake outwards and the fourth pair brings the
CTS handshake inwards. There is no need to carry the ground from
one device to another.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 56

This RS422 arrangement allows data to be transmitted and
received simultaneously since each signal has its own data cable
pair. In addition, the receiver can set RTS true so telling the
transmitter on its CTS input that the receiver is ready to accept
data. In this way, no data will ever be transmitted when the
receiver is unable to accept it, due to a full input buffer etc. And so
no data will be lost.

RS422 Serial Port Cables.

Use screened twisted pair Belden cable 9729 and 9829, L
type 2493 and 2919 or IBM Part No 4716748 cable to make the
RS422 connection. Unscreened Belden type 8795 may also be
used in less noisy environments.

The on board resistor networks terminate the receiving end
of the twisted pair cable in its characteristic impedance.

Figure 4-1. Serial Port 1 To Other PC Cable.

SERIAL PORT 1 Side Other PC SERIAL PORT Side.
9 Pin Female D Connector

9 Pin Female D Connector

Note:

i.) Receiver ends terminated in characteristic impedance

ONBOARD resistor networks.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 57

ii.) USE BELDEN TYPE 9729 etc. see above.
iii.) RS485 Gating & Multiplex Jumpers as Factory Set.

RS485 Operation.

The RS485 standard is intended for up to 32 driver receiver
pairs on the bus. The line drivers used in the Serial Solutions
RS422/485 card are designed to work correctly in both RS422 and
RS485 systems. The main difference therefore is in how the
system is implemented. Though the card uses a 9 pin D connector,
in general, not all the lines are used for RS485 systems. The
RTS+/- and CTS+/- lines, though driven by the card, are usually
not connected. In two wire, Half-Duplex configurations the TXD+
line is connected to the RXD+ whilst the TXD- line is connected
to the RXD-, only one pair of twisted wire cable is used in RS485
Half Duplex communications.
The hardware handshaking performed by the CTS+/- and
RTS+/- lines in RS422 systems are handled by a software protocol
in RS485 systems. In situations where more than one device may
transmit data on the shared data line, each cards RTS line is used
as a gating signal to enable the TXD driver only when that card
needs to transmit data, i.e. set TXD GATE or AUTO jumper. This
mechanism prevents bus contention caused by multiple
transmitters holding the line in opposing states. Revision 3 and
higher versions of this card have a facility which automatically
“gates” the RTS line, thus enabling the transmitter independently
of any software. This “Auto gating” is described in more detail in
the previous 485 half duplex section
The three wiring schemes given described below are: -

i.) RS485 One Talker Many Listeners (HALF DUPLEX)
ii.) RS485 Many Talkers Many Listeners (HALF DUPLEX.)
iii.) RS485 Many Talkers Many Listeners (FULL DUPLEX.)

RS485 Cable.

For best noise immunity use twisted pair cables to make
the RS485 connection. In Half Duplex wiring only 1 twisted cable
pair is needed. Two twisted pair cables are needed for Full Duplex

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 58

communications.

Use screened twisted pair Belden cable 9729 and 9829, UL
type 2493 and 2919 or IBM Part No 4716748 cable to make the
RS485 connection. Terminate the twisted pair cable at either end
in its characteristic impedance, which for the Belden 9729 cable is
120 Ohms. Unscreened Belden type 8795 may also be used in less
noisy environments.

RS485 One Talker - Many Listeners, Half Duplex.

There are several schemes for connecting RS485 devices
depending on the characterist ics of the system. In many cases there
will be only one device, which can transmit, data and all the others
simply listen to it. This scheme is used for theatrical lighting
intensity control in the DMX512 standard. This is shown in Figure
4-2, below. For the talker the RS485 TXD GATE jumper should
remain in the factory set position, i.e. transmitter is always
enabled. There is NO multiplexing of the TXD and RXD lines.
Data is only flowing one way, from PC outwards, and is thus a
Half-Duplex configuration, only one twisted pair cable is needed.

Figure 4-2. RS485 1 Talker Many Listeners.

Note:

The Receiver end of MAIN line terminated in
characteristic impedance by ONBOARD resistor networks, stubs
off the main not terminated.

In the above scheme, one RS485 device is talk only, it
transmits data, but it does not receive any. The other RS485
devices are receive only, they do not transmit any data at all.
Figure 4-3 gives the RS485 Gating jumper settings.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 59

Figure 4-3 Half Duplex Settings of RS485 Multiplex

• Both jumpers shorted, causing the RXD- & TXD- and the

RXD+ & TXD+ signals to short together at the 9-pin
connector.

RS485 Many Talkers- Many Listeners, Half Duplex.

Another popular RS485 layout is for multiple talkers and
multiple listeners. This is shown in Figure 4-4, below. This is also
known as "party line" transmission. It is imperative to have some
method of preventing two devices trying to drive the data lines at
the same time. The normal method is to use the RTS line as a talk
enable. The RTS line should go true immediately prior to the data
transmission and go false immediately after the last byte in the
stream is sent. See Figure 4-3 for jumper settings.

Figure 4-4. RS485 Many Talkers & Listeners. Half Duplex

TXD1+
TXD1-

+TXD n

-TXD n

120

W

-RXD1

+RXD2

120

W

-RXD2
+TXD2

-TXD2

+RXD1

+RXD3

-RXD3
+TXD3

-TXD3

+RXDn-1

-RXDn-1
+TXDn-1

-TXDn-1

-RXDn
+RXDn

Note:

BOTH ends of MAIN line terminated in characteristic
impedance, stubs off main line not impedance, since both ends
receive. The twisted pair ends are wired to both RXD+ & TXD+
and RXD- & TXD- at each RS485 device!

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 60

RS485 Many Talkers- Many Listeners, Full Duplex.

The RS485 many talkers, many listeners, Full Duplex
system can be used when all the RS485 devices have separate
Transmit and Receive channels. There is NO multiplexing of the
TXD and RXD signals on the same device. This system is
especially useful when there is no flow control available on the
PC, usually due to the use of a third party communications
program that prevents the use of the RTS signal as a "transmit
enable" control, via the TXD GATE jumper. It can be used in the
following situations:­ a) The PC is connected to only ONE RS485 device.
b) The PC is communicating with several RS485 devices that
are each able to recognize and respond to their own unique
address. The RS485 devices only drive their TXD lines
when they are responding to requests from the PC to send data. In
effect, the RS485 device's address and the command it receives is
used to control access to the devices TXD channel.

This is a Full Duplex system. Two twisted pair cables are
required. One twisted pair, is the PC's TXD channel, it carries the
data sent from the P C's TXD outputs to the RXD inputs of each of
the RS485 devices. The second twisted pair, is the Devices TXD
channel, it carries the data sent from each of the devices' TXD
outputs to the RXD inputs of the PC.

The advantages of this system are great, since no new
communications, software is needed, and the PC can talk and listen
at the same time. In effect, the handshaking is performed by the
intelligence of the RS485 devices attached to the PC.
When wired as in Figure 4-6 below, the PC can transmit data at
any time and all the RS485 devices #1 to #n simultaneously
receives it.

Only one of the RS485 devices may talk, i.e. transmit data,
at any one time. Each RS485 device recognizes commands and
data addressed to it, it only talks when the PC commands it to do
so. When the RS 485 device receives the command to talk from the
PC, it gates its TXD drivers on, sends the data down the device

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 61

TXD channel, and disables its TXD drivers. The other RS485
devices remain in the receive only mode when they are not being
addressed, they do not transmit any data at all. Figure 4-5 gives the
jumper settings for the serial card in the RS485 Full Duplex mode.

Figure 4-5. RS485 Jumpers, Full Duplex.

• Both jumpers left unconnected (not shorted).

Figure 4-6. RS485 Full Duplex.

Not

e:

The receiver end of MAIN line terminated in characteristic

impedance, stubs off the main not terminated.

Optional Grounding Arrangements.

Proper operation of the cable circuit, according to TIA
EIA: 485 A (1995) requires that the cable ground shield is not
connected directly to the equipment ground shield. A current
limiting resistor should be used in series with the shield to avoid
possible large current flow due to differences in ground potential.
Any one of the methods shown in Figure 4-7, below can do this.

PCI 1 Port RS422/485 Software Setup

Chapter 3 Page 62

Figure 4-7 - Optional Grounding Arrangements For
A PCI RS422/485 Card.

Configuration A)

Configuration B)

Configuration A)

The circuit common of the equipment is

connected to protective ground, at one point only by a 100
Ω, ±20% resistor with a power dissipation rating of 1/2W. An

additional provision may be made for the resistor to be bypassed
with a strap to connect signal common and protective ground
directly together when specific installation conditions necessitate.

GWG

S

G

GWG

1

00

Ω

S

G

SG = Signal Ground Interchange ci rcuit.
GWG = Green wire ground of power system.

= Protective ground of fra me ground.

= Circuit ground or circuit

PCI 1 Port RS422/485 Software Setup

Index

1 Megabaud...................................................................................10

115200 Baud............................................................................34, 44

16450 / 16550............................................................................6, 10

460800 Baud............................................................................34, 44

921600 Baud............................................................................34, 44

asynchronous.................................................................................10

Autogating...............................................................................10, 11

baud / baud rate ...........................................................................7, 8

BBCARDS.EXE................................................................16, 18, 21

Belden............................................................................................66

bits.................................................................................................64

buffer .............................................................................................65

Buffer.............................................................................................19

buffer / buffered.....................................................................7, 8, 10

cable.............................................................8, 15, 63, 64, 65, 66, 67

Changing COM numbers in Windows 95...............................32, 42

command ...................................................................................7, 69

Configuring Ports In Microsoft Windows NT. .............................47

connectors......................................................................................14

CTS....................................................................7, 10, 63, 64, 65, 66

data word length............................................................................10

DCD.................................................................................................7

device driver............................................................................16, 18

DSR .................................................................................................7

DTR.................................................................................................7

emulation.........................................................................................7

fail safe ..........................................................................................64

FIFO ..........................................................................................6, 10

gating.............................................................................................66

handshake..............................................................................6, 7, 64

impedance........................................................63, 64, 65, 67, 68, 70

installation.................................................................................9, 15

Installing Ports In DOS. ................................................................16

Installing Ports In Microsoft Windows 95 & 98...........................27

Installing ports in Windows 3.x ....................................................22

PCI 1 Port RS422/485 Software Setup

interrupts..........................................................................................8

jumper....................................................................66, 67, 68, 69, 70

last .................................................................................................68

lo o p bac k..........................................................................................8

Maximum Baud Rate...................................................33, 34, 43, 44

Megabaud..............................................................See 921600 baud

mode..........................................................................................7, 70

open circuit....................................................................................64

parity............................................................................................7, 8

party line..................................................................................64, 68

port / ports .................................................6, 7, 8, 10, 15, 47, 53, 63

Port Address ..................................................................................18

protocol......................................................................................7, 66

receive ...................................................................13, 67, 68, 69, 70

resistor ...............................................................................62, 65, 67

RS232..................................................................................6, 10, 13

RS422 / RS485...........................................10-13, 36, 46, 51, 62-70

RS422 Pinout.................................................................................12

RS485 Multiplex Jumper Settings.....................................36, 46, 51

RTS........................................................7, 10, 63, 64, 65, 66, 68, 69

RXD.....................................................10, 13, 63, 64, 66, 67, 68, 69

serial port.........................................................6, 7, 8, 15, 47, 53, 63

shared interrupt............................................................................8, 9

short circuit....................................................................................64

SISR...............................................................................................17

speed........................................................................................10, 62

technical...........................................................................................9

twisted pair ..........................................13, 63, 64, 65, 66, 67, 68, 69

TXD...........................................................10, 13, 64, 66, 67, 68, 69

Uninstalling Serial Solutions PCI for Windows NT.....................52

Windows..........................................................................6, 8, 47, 53