Brainboxes CC-357, PCI Velocity RS232, PCI Velocity RS422, PCI Velocity RS485 User Manual

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1.1 EDITION February 2000

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PCI VELOCITY RS232/422/485 CARD

These products conform to the following st andards:
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 RS232/422/485 CARD
OUTLINE CONTENTS

Chapter 1 - Supplied Serial Solution Software.
Chapter 2 - PCI Velocity RS232/422/485 Specifications.
Chapter 3 - PCI Velocity RS232/422/485 Software Configuration

Guide.
Chapter 4 – RS232 Pinouts and Cabling
Chapter 5 - 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 o f serial port cards.

Chapter 2 - PCI Velocity RS422/485 Specifications,

gives details of the PCI Velocity RS422/485 specifications and
shows you how t o 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 9 5, Win dows 98/ Mille nium, W indows N T.

Chapter 4 – RS232 Pinouts and Cabling
Chapter 5 - 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 grou nding systems.

TABLE OF CONTENTS

CHAPTER 1 SERIAL SOLUTIONS SOFTWARE....7

INTRODUCTION.............................................................................7

I

NTRODUCING SERIAL SOLUTION SOFTWARE.................................7

S

ERIAL SOLUTIONS FOR DOS.......................................................7

S

ERIAL SOLUTIONS FOR WINDOWS 3.X .........................................9

S

ERIAL SOLUTIONS FOR WINDOWS 9X..........................................9

S

ERIAL SOLUTIONS FOR WINDOWS NT....................................... 10

C

OMPLETE DOCUMENTATION AND TECHNICAL BACKUP. ............. 10

CHAPTER 2 PCI VE LOCI T Y RS232/422/485

HARDWARE SETUP...................................................11

INTRODUCTION...........................................................................11

PCI RS232/422/485 C

ARD FEATURES........................................11

A

UTOGATING.............................................................................12

C

ONFIGURING THE PCI RS232/422/485 CARD. ......................... 14

Full Duplex Settings. ............................................................. 14

With Half Duplex Settings...................................................... 14

CHAPTER 3 INSTALLING THE PC CARD IN THE

COMPUTER.................................................................15

SERIAL CA

R

RD INSTALLATION...................................................... 15

Problems!.............................................................................. 17

CHAPTER 4 PCI VE LOCI T Y RS232/422/485

SOFTWARE CONFIGURATION ..............................18

INTRODUCTION...........................................................................18

DOS I

NSTALLATION...................................................................18

Determining PCI RS232/422/485 Resources.......................... 18

Baud clock control is at I/O address 02d0..............................19

NEWCOM.SYS Parameters....................................................19

Configuring And Installing NEWCOM.SYS............................21

Modifying Command Line Parameters...................................22

W

INDOWS 3.X INSTALLATION.....................................................23

Determining PCI RS422/485 Resources.................................23

Windows 3.x Software Installation......................................... 24

Serial Port Installation. ......................................................... 25

Configuring The COM Ports..................................................27

Deleting Ports in Windows. ...................................................28

Restarting Windows............................................................... 28

W

INDOWS 95 INSTALLATION...................................................... 29

Card Settings In Windows 95.................................................33

PCI RS232 Port Settings In Windows 95................................34

Maximum Baud Rate Settings. ...............................................36

PCI RS422/485 Port Settings In Windows 95........................ 39

Maximum Baud Rate Settings. ...............................................40

W

INDOWS 98/MILLENIUM INSTALLATION................................... 43

Card Settings In Windows 98/Millenium............................... 47

PCI RS232 Port Settings In Windows 98/Millenium...............48

Maximum Baud Rate Settings. ...............................................50

PCI RS422/485 Port Settings In Windows 95........................ 53

Maximum Baud Rate Settings. ...............................................54

W

INDOWS NT 4.0 INSTALLATION...............................................57

Software Installation..............................................................57

Examining Card Configuration..............................................58

Configuring Ports..................................................................59

Advanced Port Settings..........................................................60

Uninstalling Serial Solutions PCI.......................................... 62

CHAPTER 4 RS232 PINOUTS AND PORT

CABLING. ....................................................................64

INTRODUCTION...........................................................................64

The RS232 Standard..............................................................64

Serial Port Pin Outs...............................................................65

9 P

IN D SERIAL PORT RS232 CABLES......................................... 65

9 P

IN D SERIAL PORT CONNECTION TO ANOTHER PC................. 66

9 P

IN D SERIAL PORT TO A MODEM...........................................68

9 P

IN D SERIAL PORT LOOP BACK CONNECTOR.......................... 68

CHAPTER 5 ADDITIONAL RS422/485 OPERATION

........................................................................................70

THE RS422 STANDARD..............................................................70

T

HE RS485 STANDARD..............................................................70

T

ERMINATING IMPEDANCE’S. .....................................................71

T

HERE IS NO NEED TO ADD ANY MORE AT THE PC END................. 71

F

AIL SAFE OPEN CIRCUIT DETECT ION.........................................72

F

AIL SAFE SHORT CIRCUIT PROTECTION.....................................72

RS422 O

PERATION.....................................................................72

RS422 Serial Port Cables. .....................................................73

RS485 O

PERATION.....................................................................74

The three wiring schemes given described below are: -..........74

RS485 Cable.......................................................................... 75

RS485 One Talker - Many Listeners, Half Duplex.................. 75

RS485 Many Talkers- Many Listeners, Half Duplex...............76

RS485 Many Talkers- Many Listeners, Full Duplex. ..............77

Optional Grounding Arrangements........................................78

INDEX...........................................................................80

PCI Velocity RS232/422/485 Serial Solutions

Chapter 1 Page 7

Chapter 1

SERIAL SOLUTIONS SOFTWARE

Introduction.

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

Introducing Serial Solution Software.

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

S erial Solutions is made up of the follow ing components: ­Serial Solutions for DOS
Serial Solutions for Windows 3.x
Serial Solutions for Windows 95
Serial Solutions for Windows NT

All the Serial S olutions drivers have the following features: -

• 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

schem es.

• 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 prog rams: ­NewCOM.sys A device driver, it supports COM1 to COM16,

allo wing 16 serial ports to be used under DOS. It
also includes an interrupt handler for enhanced
performance with user definable buffer sizes.
Accessible from all DOS languages, it is the heart

PCI Velocity RS232/422/485 Serial Solutions

Chapter 1 Page 8

of the Serial So lution.
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 dr iver providing support for 24 ports.
NewCOM32.sys A device dr iver 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 t hat re po rt s t he sett ings of the various serial

ports. Fle xible and fa st!
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

applicat ions on them. So urce code, make files and

compiled ready to run prog rams 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 NE WBIOS r outines as well as t he simple file

I/O t o por ts. T hey 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 t o check that t he serial port at a particular I/O

address is functioning correctly and is connected to

PCI Velocity RS232/422/485 Serial Solutions

Chapter 1 Page 9

the particular IRQ line. The program correctly

identifies the UART type by employing the built in

lo o p ba ck c a pa bility of t he P C s er ia l por t c hip , 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 Workgr oups 3.11.
Se rial Solut ions fo r Windows 3.x c onsists of t he following

programs: ­Setup. exe The install ro utine for t he package.

Port.DLL Enhanced Control Panel applet. Allows

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

multipor t card s u sing s hared in terrup ts.
BbLynx.drv Replacement for COMM. DRV.
LynxAPI.dll Enhancement to the Windows Comms API’s

allowing support for more t han 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 cor r ectly the easy way.

Serial Solutions For Windows 9x.

Windows 95 has an improved communication API and direct ly
support s up t o 255 ports. Our Windows 95 driver suppor ts the shared
inter rupt mechanism u se d on our multip ort ca rds . Se rial Solutions
for W indows 95 con sists of the following pr ograms: -

SSCards.inf The information file to aid the installation process

“Have Disk....”

S smod em.inf Setu p file for Ser ial Solutions modems.

PCI Velocity RS232/422/485 Serial Solutions

Chapter 1 Page 10

sscardui.dll
ssportui.dll The device manager configur ation DLLs and…
ssenum.vxd
ssv485.vxd ...t he virtual device drivers providing the shared

ssvel.vxd interrupt handler s and dispatch routines etc for the
ssmult. vxd various Serial Solutions serial cards.
ssm485.vxd

Serial Solutions For Windows NT.

Windows NT has an impr oved communication API and directly
support s up to 255 po rts. No extr a dr iver is necessary for Windo ws
NT to drive mu ltiport cards. Se rial S olutions for W indows NT
consists of the following pr ogra ms: -

Setup.exe Expands into the Control Panel applet and associated

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

S smod em.inf S etup file for S erial Solutions mod ems .

Complete Do cumenta tion and Technical Ba ckup.

We believe in supplying complete documentation with every
package we sell. The Serial S olution Software Package is no
exception, it has an attract ive manual in an A5 binder, containing
over 150 pages of in-dept h technical detail with comprehensive
indexes and table of contents. We guarantee your Ser ial Solution
Software package for a full 12 months from purchase. A complete
technical backup service is available to ensure that you get the
maximum per f ormance out of your in vestment.

PCI Velocity RS232422/485 HARDWARE SETUP

Chapter 2 Page 11

Chapter 2

PCI VELOCI T Y RS232/422/485

HARDWARE SETUP

Introduction.

This chapter details the specifications of the PCI Velocity
RS232/422/485 card and explains how to co nfigure t he RS485
Multiplex jumper s p resent on th is c ard . This half-size d card w ill
work happily in any P CI 2 .0 or g reater compliant P C c ompatib le.

PCI RS232/422/485 Card Features.

• One 9 pin D RS422/485 serial port.

• One 9 pin D RS232 serial port.

• Reliable communications up to 4000 feet, 1.2 Kilometers.

• 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 opt ions.

• 1 start bit always sent.

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

• TXD, RXD, RTS, and CTS signals

• RS485 TXD/RXD multiplex selectable by jump er s: - either

FULL DUPLEX or HALF-DUPLEX

• Autogat ing low level RS485 half duplex (2 wire) contro l

• Fully double buffered for reliable asynchronous operat ion.

• High-speed integrated circuitry ensures oper ation with fast PC’s

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

PCI Velocity RS232422/485 HARDWARE SETUP

Chapter 2 Page 12

PCI RS422/485 Serial Port Features

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 Le vel Cur rent: - 60mA max.
Lo w Leve l Current: 60mA max.
Receivers: SN75175.
Difftial I/P threshold: 200mV max.
Hysteresis: 50mVolt typical.
Input Impedance: >12K Ohm without terminators.

Autogating.

Multitasking operat ing systems, like Windows 95, Windows NT,
OS/2 and UNIX, cannot successfully use t he RTS line to contr ol 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 t he data has gone. This is due to the time
slicing mechanism used by these multitasking op er ating systems.
T he interrup t se rv ice r outin es in multita sk ing 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 r e ply to the PC may be lost since the serial
por t tr ansmitter is s till gated onto the twisted pair c able.

To overcome this problem, Autogating hardware has been added to
the to the RS422/485 card. T his automatically detects the start of the
PC’s data transmissions, and gates the PC’s transmit ter onto the
twisted pair cable. It then auto matically 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 writt en to use RS485 in any op er ating system. To all intents
and purposes, it looks just like an ordinary RS232 COM port to the
host PC. Aut ogating for half duplex oper ation is a necessity for
Window s 9 5/9 8, N T and the forthcoming Windows Millennium an d
Windows 2000.

PCI Velocity RS232422/485 HARDWARE SETUP

Chapter 2 Page 13

Figure 2-1. PCI VELOCITY RS232/422/485 Layout.

Figure 2-2. 9 Pin D Connector RS422/485 Port Pinouts.

Figure 2-3. 9 Pin D Connector RS232 Port Pinouts.

P
O
R
T
#1

P
O
R
T
#2

TX/
RX1 +

TX/
RX1 -

MULTIPLEX

RS485

RS485 Multiplex jumper block

PIN 1 - DATA C ARRIER DETECT (DC D)

P IN 6 - DATA S E T R EA DY (DS R )

PIN 8 - CLEAR TO S END (CTS)

P IN 3 - TR AN S MIT TE D DATA (TX D)

PIN 2 - REC EIVED D ATA (R X D)

P IN 4 - DATA T ER M INAL RE ADY (DT R)

PIN 7 - REQ UEST TO SEND (R TS)

P IN 9 - R ING IN DICAT O R (RI)

P IN 5 - GR OUND (G ND)

PIN 5 - GROUND (GND)

PIN 1 - TRANSMITTED DATA (TXD-)

PIN 6 - RE CEIVED DATA (RXD -)

PIN 8 - CLEAR TO SEND (CTS-)

PIN 3 - REQUEST TO SEND (RTS-)

PIN 2 - TRANSMITTED DATA (TXD+)

PIN 4 - REQUEST TO SEND (RTS+)

PIN 7 - RECEIVED DATA (RXD+)

PIN 9 - CLEAR TO SEND (CTS+)

PCI Velocity RS232422/485 HARDWARE SETUP

Chapter 2 Page 14

Configuring The PCI RS232/422/485 Card.

PCI cards require no hardware configuration for IRQ and address
allocation - th is is don e a utomatically at s tart up by th e PC.
However, t he PC Velocity RS232/422/485 has a set of jumpers for
configuration of RS485 multiplex modes, details of configur ing
these jumpers is show n be low.

Full Duplex Settings.

•

Bot h jumpers left unconnected (not sho r ted).

With Half Duplex Settings.

• Bot h jumpers shorted, causing the RXD- & TXD- and the

RXD+ & TXD+ signals to short together at the 9-pin
connector . The multip lex jumpers sh ould only b e s et for
RS485 Half Duplex operation, when one twisted pair is used
to interconnect both tr ansmit and receive lines.

NOTE: Any changes to RS485 Multiplex Operation must be
accompanied with appropriate changes to the driver softwar e; see
Chapter 3 - “PCI Velocity RS232/422/485 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 Velocity RS232422/485 Installing the Card

Chapter 3 Page 15

CHAPTER 3

INSTALLING THE PC CARD

IN THE COMPUTER.

Serial Carrd Installation.

Once the card has been cor r ectly configured it can then be installed
in the PC.

Finally cables should be attached and communicatio n with the serial
peripheral devices should be established.

P rov ided that the insta llation is a ttacked in this orde rly mann er,
everyt hing should wor k first time. If it does not then check the
software selectable commu nications paramet er s, Baud r ate, Par ity,
stop bits first, and that the communications program is attempting to
access the serial por t installed. If this fails to so lve the problem
check the cable connections. Finally check that the card is indeed
configur ed as you believed!

NOTE

: Always turn the computer OFF be for e insta lling or

removing any interface board.

STEP 1: Before the PC card can be inst alled the power to the PC
MUST be switched OFF!

STEP 2: Remove the case.

PCI Velocity RS232422/485 Installing the Card

Chapter 3 Page 16

Figure 3-1. Removing Blanking Cover

STEP 3: Cho ose an empty appropriate expansion
slot. Remove the blanking cover protecting the
slot on t he PC back panel. KEEP the blanking
cover screw safely fo r later (Figure3-1).

Figure 3-2. Inserting The PC Serial Card.

STEP 4: Now insert the PC Serial card in the
available slot. Be careful to ensure that the
gold plat ed PCB fingers fits neatly into the I/O
expansion connector. Press do wn firmly but
evenly on the top of the PC Serial card (Figure
3-2).

STEP 5: The D connectors sho uld fit neat ly through the slot’s
apertur e to the outside world. NB. Use the screw kept back from the
blanking cover to screw t he PC Serial retaining bracket into the PC
back panel housing.

STEP 6: Now replace the system units cover by carefully sliding it
down and back over the system unit . Replace the cover mounting
screws.

STEP 7: After at taching all the appropriate cables, power up the PC.
Do not forget the mains power cable!

The PC should power o n in the normal way.

PCI Velocity RS232422/485 Installing the Card

Chapter 3 Page 17

Problems!

If the system fails to power up normally check the following.:
i.) Ensure that the PC Serial card is installed correctly.

ii.) Ensure that other cards in the PC have not been upset.
iii. ) E nsure that the p ower is c onnected a nd the PC is sw itched

ON!

n

I f all th es e have bee n checked and the P C still does not
power up then there is probably a fault in the hardware. Please
contact technical support.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 18

Chapter 4

PCI VELOCITY RS232/422/485

SOFTWARE CONFIGURATION

Introduction.

This sect ion contains the installation procedures of the PCI
VELOCITY RS232/422/485 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 t he PCI
RS232/422/485 card is inserted:

1. Determining the reso ur ces that t he card has claimed.

2. Infor ming the Serial So lutions DOS device driver of those
resources.

Determining PCI RS232/422/485 Resources.

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

• Run BBCARDS.EXE, from the supplied Ser ial Solutions

CDR OM by typing the following:
D:\diskimg \ ssu til\pci\BBCARDS

Where D:\ is the Letter of your CDROM drive
BBCARDS.EXE will retu rn a s tr ing that looks similar to the

follow in g (valu es contained in the string may diffe r in individua l
P C’s d ue to re sou rce availa bility):

card 1 is on bus 0, device 16, function 0
Card ID=5, revision 2: Dual Velocity RS232/422/485

interrupt line 11 has been assigned
2 sets of 16550-compatible registers are at I/O address 0140

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 19

Baud clock control is at I/O address 02d0

Write 0xf6 for /8 (default), 0xf2 for /4, 0xd6 for /2, 0xd2 for /1.

• Not e 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
RS232/422/485 driver software is used to set up the card in DOS
and has the follo wing synta x:

NEWCOM.SYS /A port address, /I IRQ,range /B number buffer /S
buffer /H hardw are handsha ke

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 specif ies card i nterrupt and COM port range. The

COM port range specifies t he COM port(s). Range may be a
sing le port OR a range of p orts.

/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-maxpor t.

/S buffer Set size of all buffers in bytes, buffer is rounded
to the nearest power o f 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 select s which hard ware ha ndshake
type to use on the specified ports. This is used in the
following manner: /H range, hs where range specifies the
COM port or ports and hs selects handshake type.
Handshake types available are:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 20

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

CTS is input tr ue. 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 external serial 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 t he PC sets RT S false. RTS is used
as a transmit gating control. The CTS, DSR and
DC D inp ut s a re ig no re d. The D TR ou tp ut line is
set true just in case the external serial device
needs a true signal.

Type 3 RS485 Send o nly - This is a half duplex, t ransmit

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, DS R and DCD inputs are ignored. The RTS
and DTR o ut put 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 automatically.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 21

Configuring And Installing NEWCOM.SYS

To load the Serial S olutions for DOS device driver an entry needs
to be a dded to the CO NFIG.S YS file . A ny simple tex t editor,
EDIT for example, can edit the CONFIG.SYS file for example.
T he in stallation proce dur e give n below is for a PCI
RS232/422/485 as COM5 & COM6.

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.

/A5-6,0140

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

IRQ, Range.

/I 11,5-6

11 is the IRQ and since the COM port is COM5 is enter ed 5.

Numb er B u ffer.

/B6

Six buffers are defined, t ho ugh only four ports are in use - this is
because buffers in DOS are assigned in a sequential or der fro m
COM1. Since the PCI Velocity RS232/422/485 have been
assigned a COM port values of 5 and 6, all preceding COM ports,
must have buffers assigned to them also.

Buffe r Size.

/S512
Buffer size set to 512 bytes.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 22

Hardwa re Ha ndshaking.

/H,4

Type 4, 3 Wire Handshake selected for all por ts. Type 4, 3 Wir e
Handshake selected for all por ts.

Modifying Command Line Parameter s .

When “ as se mb led” the NEW CO M.S YS c ommand line looks
like…

DEVICE=NEWCOM.SYS /A5-6,0140 /I 11,5-6 /B6 /S 512 /H,4
…and should be entered into the CONFIG.SYS file. Once you are

sure that these parameters have been entered cor r ectly, rest art your
PC and your PCI RS232/422/485 card should be ready to use
immediately. Samp le ter minal applica tions are p rov ided on “Serial
Solutions CDROM” enabling communications to be established to
your peripherals quickly and easily.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 23

Windows 3.x Installation.

The Windows 3.x installation procedure consists o f two steps after
the PCI Velocity RS232/422/485 card is inserted:

1. Determining the reso ur ces that t he PCI Velocity
RS232/422/485 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 So lutions

CDROM” by typing the following:

D:\diskimg \ ssu til\pci\BBCARDS

Where D:\ is the Letter of your CDROM drive
BBCARDS.EXE will retu rn a s tr ing that looks similar to the

follow in g (valu es contained in the string may diffe r in individua l
P C’s d ue to re sou rce availa bility):

card 1 is on bus 0, device 16, function 0
Card ID=5, revision 2: Velocity RS232/422/485

interrupt line 11 has been assigned
2 sets of 16550-compatible registers are at I/O address 0140

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

• Not e down IRQ and I/O which in this case:

The IRQ = 11
The I/O address = 0140

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 24

Windows 3.x Software Installation.

Place the supplied Serial Solut ions CDROM in a suitable dr ive.
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 Progr am M ain Screen is d isp layed:

By de fault, all component options w ill be in stalled, selecting the
“D el All” button will s ele ct all ins talled compon ents for d ele tion
and “ Add All” c hooses all uninsta lled compon ents 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 por ts COM1 to COM9 are to be used then de-select
the Comms API librar y option in the “Insta ll” c olumn. T his lib rary
is only necessary to allow t he use o f logical port s gr eater t han
COM9 e.g. COM10, COM11 etc.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 25

• When you have made your choice of Component Options click

Continue and when the setup program has finished select the
Done butt on.

Note: If the Serial Port dr iver options has been select ed, after the

setup progr am has fin ished, W indows w ill display a restart
message - answer Yes and Serial Solu ti ons will be ready to ru n
up on Windows restarting.

Serial Port Installation.

• From M ain, select Control P anel:

• Click on Serial Port s:

T he following dialogue will be dis played:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 26

To add a COM por t:

• Click on th e add button and a Wind ow simila r to the following
will be dis played:

• In Standard Settings:

• In the COM Base field, enter the valu e 0140.

Note: COM po r ts are defined with an i/o address range,
which in this case, begins at 0140 and all subsequent por ts
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 Velocity RS232422/485 Software Setup

Chapter 3 Page 27

Note: The values used in the above section were those

ret ur ned by the BBCARDS progr am, as described in the
above section.

When you have finished, click on OK. A restart mes sa ge will be
displayed ; to save t ime only restar t w he n both por ts have bee n
added and correct ly configured.

• After adding the COM ports the COM Ports Window will look
similar to the follow ing:

Configuring The COM Por t s.

• From the COM Por ts windo w cho ose the por t that you wish to
configure and click on Settings - the following dialogue w ill
be displayed:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 28

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

Baud Rate: 9600
Data Bits: 8
Parity: None
to p Bits: 1.0
Flow: None

Change the communications Settings in the COM Po r ts 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 be en re moved from the system.

Not e. Never try to leave out a ser ial port number when using the
delete button, because Windows may automatically shift serial por t
number s w hich r es ults in a mis-match of s ettin gs in the S erial
Ports Applet (COM1-COM4 only).

Restarting Windows.

Whenever certain values have been enter ed or changed in the
hardware set tings window, a message pro mpting to restart
Windows will a ppe ar. Only after h aving made ALL the necessary
changes restart Windows so that the new settings come into effect.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 29

Windows 95 Installation.

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

• Switch off your co mputer, insert your PCI RS422/485 card
into a free PCI slot, as described in t he sect ion “Hardware
Installation” in Chapter 2, and switch your computer on again.

• During the booting p roce ss , Wind ows 95 w ill de tect th e PCI
Velocity RS232/422/485, but will disp lay it simp ly as a “PC I
CA RD ”, a nd you will briefly see a message box to this effec t.

• Windows will th en dis play the “Updat e Device Driver
Wizard”, which asks you to “insert any disk which came with
the PCI card”. Insert the Serial Solutions CD ROM into an
appropr iate drive and click ‘Next’.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 30

• The Wizard should then display the following:

• Click Oth er Locations

• In the location space type <drive>:\diskimg\sswin9x where

drive is the appropriate letter for your CDROM dr ive

• Click OK

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 31

• Click Finish

• After copying the file , Windows 9 5 will then de tec t each of the

serial ports in turn and install them as velocity ports.

• Using the right-hand mouse button click on the My Computer
icon on your desktop. Click on Properties.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 32

• Click on th e Device Manager tab

When the “Device Manager” is viewed the PCI Velocity
RS232/422/485 card will appe ar u n der the “Multi-function
adapters” br anch. A lso, tw o ve locity ports w ill app ea r unde r the
“Ports (COM & LPT) branch”.

For mos t u se rs who have 4 or les s 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 availa ble CO M
ports.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 33

Card Settings In Windows 95

• Select the PCI Velocity RS422/485 card from the “Multi-
Function Adapter” entr y in Device Manager serial and click

on pro per ties to view the cards general pro per ties.

• Click on th e 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
ver s ion o f the d river.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 34

I n this wind ow, the C OM por t assign ment may be changed, s imply
by s ele cting a ne w COM p ort 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 port s ar e in use - port
availability can be che cked b y v iewing the Device Manager:

All C OM ports pres ent will be lis ted unde r th e entry “Port s ( C O M
& LPT). ” T he above screenshot s indicates that COM2 - 4 and
COM6 and above are not installed, and therefore may be used.

PCI RS232 Port Settings In Windows 95.

Double clicking on a Velocity RS485 Port entry from the entry
“Ports (Com & LPT)” branch in Device Manager w ill the
display general pro p er ties windo w for the selected port ( in this
case COM5).

• Selecting the Po r t Settings t ab produces:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 35

Settings available in this window are:

1. Baud Rate - determines the baud rate at which the selected
port operates, t he 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 sele cts the maximum baud rate at w hich the p ort may
operate. The t able below, indicates the ranges o f baud rate
values available at t he Maximu m Baud Rate Settings.

Change to suit remote device.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 36

Maximum Baud Rate Settings.

Ma ximum Ba u d Rat e

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: Ma ny serial comms applications will not a ctua lly
register the ports as running at baud rat es of above 115200.

7. Restore Defaults - when clicked, resets t he selected COM por t

to the follow ing value s:

Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow C ontrol: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 37

Click ing on the S eria l Solution s ta b will display:

Settings available in this window are:

1. FIFO Settings.

• Enable FIFO - t urns the selected ports FIFO buffer on or off.

I t is str ongly rec ommende d that th e FIF O for both ports is left
enabled.

• Extend FIFO - when checked, extends the selected ports FIFO

buffer from 16 to 64 bytes.

• Receive Buffer - These settings allow the select ion of a

receiver FIFO tr igger setting. Selecting a low value will allow

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 38

the inter r upt to be serviced quicker, which is good for slow
machin es . If you have a fast machine, setting a high value will
give you more time for multi-tasking operations.

• Transmit Bu ffe r - T hese set tings allow the selection of a

tran smitter FIFO trig ger se tting. S electing a low valu e w ill
send fe we r da ta-bytes per interrup t, and this is recommen ded if
you are communicating to a slower machine. Selecting a high
value will send more data-b ytes p er interrupt, and w ill give
mor e time for multi-tasking operations.

2. Automatic Hardware Flow Control. One of two options may

be selected:

• Off (De fault) - This w ill turn off au tomatic flow contr ol. (If

you hav e no data transfer p roblems then se lec ting this op tion is
fine.)

• RTS/CTS - This will us e the R TS a nd CTS lines for automatic

hardware flow contro l.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 39

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 w ill the
display general pro p er ties windo w for the selected port ( in this
case COM5).

• Selecting the Po r t Settings t ab produces:

Settings available in this window are:

1. Baud Rate - determines the baud rate at which the selected port
operates, t he maximum value available is dependant upon t he
Maximum B au d Rate Setting (see be low.)

2. Data Bits.

3. Parity.

4. Stop Bits.

5. Flow C ontrol.

6. Maximum Baud Rate Setting - four values are available,

which sele cts the maximum baud rate at w hich the p ort may
operate. The t able below, indicates t he ranges o f baud rate values
available at the Maximu m Baud Rate Settings.

Change to suit remote device.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 40

Maximum Baud Rate Settings.

Ma ximum Ba u d Rat e

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: Ma ny serial comms applications will not a ctua lly
register the ports as running at baud rat es of above 115200.

7. Restore Defaults - when clicked, resets t he selected COM por t
to the follow ing value s:

Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow C ontrol: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 41

Click ing on the S eria l Solution s ta b will display:

Settings available in this window are:

3. FIFO Settings.

• Enable FIFO - t urns the selected ports FIFO buffer on or off.

I t is str ongly rec ommende d that th e FIF O for both ports is left
enabled.

• Extend FIFO - when checked, extends the selected ports FIFO

buffer from 16 to 64 bytes.

• Receive Buffer - These settings allow the select ion of a

receiver FIFO tr igger setting. Selecting a low value will allow
the inter r upt to be serviced quicker, which is good for slow
machin es . If you have a fast machine, setting a high value will
give you more time for multi-tasking operations.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 42

• Transmit Bu ffe r - T hese set tings allow the selection of a

tran smitter FIFO trig ger se tting. S electing a low valu e w ill
send fe we r da ta-bytes per interrup t, and this is recommen ded if
you are communicating to a slower machine. Selecting a high
value will send more data-b ytes p er interrupt, and w ill give
mor e time for multi-tasking operations.

4. Automatic Hardware Flow Control. One of two options may

be selected:

• Off (De fault) - This w ill turn off au tomatic flow contr ol. (If

you hav e no data transfer p roblems then se lec ting this op tion is
fine.)

• RTS/CTS - This will us e the R TS a nd CTS lines for automatic

hardware flow contro l.

5. 485 Mode offers the options:

• Half Duplex / Full Duplex(default) - are used in conjunction

with the RS485 Multiplex Jumper Settings.

NOTE: These software sett ings must match the RS485
Multiplex Jumper configur ation , as described in the
section “RS485 Multiplex Jumper Settings” in
Chapter 2, to ensure accurate and error free dat a
tr ansmission.

• CTS Hold True, determines whether the CTS handshake

signal is INPUT from the external serial device or is
permanently forced t r ue on the card. The serial ports o wn RTS
OUTPUT handshake signals are always taken out to the serial
port connector .

6. Restore - when this button is clicked the settings in the current

win dow w ill b e rese t to the d efa ult values of:

Enable FIFO: On (Checked)
Extend FIFO: Off (Unc he c ked)
Receive Buffer: 3

rd

fr om left.

T rans mit Bu ffer: 16

Automatic Hardware

flow Control: Off
485 Mode: Full duplex.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 43

Windows 98/Mille nium Installation.

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

• Switch off your co mputer, insert your PCI RS422/485 card

into a free PCI slot, as described in t he sect ion “Hardware
Installation” in Chapter 2, and switch your computer on again.

• During the booting p roce ss , Wind ows 98 w ill de tect th e PCI

Velocity RS422/485, but will di sp lay it simply as a “PCI
CA RD ”, a nd you will briefly see a message box to this effec t.

• Windows will th en dis play the “Updat e Device Driver

Wizard”, which asks you to “insert any disk which came with
the PCI card”. Insert the Serial Solutions CD ROM into an
appropr iate drive and click ‘Next’.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 44

• The Wizard should then display the following:

• Select Search for the best driver for your device.

• Click Next

• Click S pecify a location

• In the location space type <drive>:\diskimg\sswin9x where

drive is the appropriate letter for your CDROM dr ive

• Click Next

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 45

• Click Next

• Click Finish

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 46

• After copying the file , Windows 9 8 will then de tec t each of the

serial ports in turn and install them as communications por ts.

• Using the right-hand mouse button click on the My Computer

icon on your desktop. Click on Properties.

• Click on th e Device Manager tab

When the “Device Manager” is viewed the PCI Velocity
RS232/422/485 card will appe ar u n der the “Multi-function
adapters” branch. Also, a Velocity RS232 and a Velocity RS485
P ort will a ppe ar u n der the “Ports (COM & LPT) branch”.

For mos t u se rs who have 4 or les s COM ports the new ports will
appear as COM5 and COM6as pictured above, for users with mor e
than 5 COM ports the new por ts will a ppear as the first av ailable
COM po r ts.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 47

Card Settings In Windows 98/Mille nium.

• Select the PCI Velocity RS232 & RS422/485 card from the

“Multi-Function Adapter” entry in Device Manager serial
and click on propert ies to view the cards general properties.

• Click on th e 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
ver s ion o f the d river.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 48

I n this wind ow, the C OM por t assign ment may be changed, s imply
by s ele cting a ne w COM p ort value from the pull down menu
relevant to the port. However, COM port usage other than those
for the PCI Velocity RS232 & RS422/485 card itself are not
checked, so it is advisable to first check which COM port s ar e in
use - port ava ilability can be chec ked by vie wing th e Device
Manager:

All C OM ports pres ent will be lis ted unde r th e entry “Port s ( C O M
& LPT). ” T he above screenshot s indicates that COM2 - 4 and
COM6 and above are not installed, and therefore may be used.

PCI RS232 P ort Settings In Windows 98/M illenium.

Double clicking on a Velocity RS485 Port entry from the entry
“Ports (Com & LPT)” branch in Device Manager w ill the
display general pro p er ties windo w for the selected port ( in this
case COM5).

• Selecting the Po r t Settings t ab produces:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 49

Settings available in this window are:

1. Baud Rate - determines the baud rate at which the selected

port oper ates, t he 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 sele cts the maximum baud r ate at which the p ort
may operat e. T he t able below, indicates the ranges of baud
rate values available at the Maximum Baud Rate Settings.

Change to suit remote device.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 50

Maximum Baud Rate Settings.

Ma ximum Ba u d Rat e

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: Ma ny serial comms applications will not a ctua lly
register the ports as running at baud rat es of above 115200.

7. Restore Defaults - when clicked, resets the selected COM

port to the following value s:

Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow C ontrol: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 51

Click ing on the S eria l Solution s ta b will display:

Settings available in this window are:

7. FIFO Settings.

• Enable FIFO - t urns the selected ports FIFO buffer on or off.

I t is str ongly rec ommende d that th e FIF O for both ports is left
enabled.

• Extend FIFO - when checked, extends the selected ports FIFO

buffer from 16 to 64 bytes.

• Receive Buffer - These settings allow the select ion of a

receiver FIFO tr igger setting. Selecting a low value will allow

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 52

the inter r upt to be serviced quicker, which is good for slow
machin es . If you have a fast machine, setting a high value will
give you more time for multi-tasking operations.

• Transmit Bu ffe r - T hese set tings allow the selection of a

tran smitter FIFO trig ger se tting. S electing a low valu e w ill
send fe we r da ta-bytes per interrup t, and this is recommen ded if
you are communicating to a slower machine. Selecting a high
value will send more data-b ytes p er interrupt, and w ill give
mor e time for multi-tasking operations.

8. Automatic Hardware Flow Control. One of two options may

be selected:

• Off (De fault) - This w ill turn off au tomatic flow contr ol. (If

you hav e no data transfer p roblems then se lec ting this op tion is
fine.)

• RTS/CTS - This will us e the R TS a nd CTS lines for automatic

hardware flow contro l.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 53

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 w ill the
display general pro p er ties windo w for the selected port ( in this
case COM5).

• Selecting the Po r t Settings t ab produces:

Settings available in this window are:

1. Baud Rate - determines the baud rate at which the selected port
operates, t he maximum value available is dependant upon t he
Maximum B au d Rate Setting (see be low.)

2. Data Bits.

3. Parity.

4. Stop Bits.

5. Flow C ontrol.

6. Maximum Baud Rate Setting - four values are available,

which sele cts the maximum baud rate at w hich the p ort may
operate. The t able below, indicates t he ranges o f baud rate values
available at the Maximu m Baud Rate Settings.

Change to suit remote device.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 54

Maximum Baud Rate Settings.

Ma ximum Ba u d Rat e

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: Ma ny serial comms applications will not a ctua lly
register the ports as running at baud rat es of above 115200.

7. Restore Defaults - when clicked, resets t he selected COM por t
to the follow ing value s:

Baud Rate: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow C ontrol: Xon / Xoff
Maximum Baud Rate Setting: 115,200

Selectable

Baud

Rates

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 55

Click ing on the S eria l Solution s ta b will display:

Settings available in this window are:

9. FIFO Settings.

• Enable FIFO - t urns the selected ports FIFO buffer on or off.

I t is str ongly rec ommende d that th e FIF O for both ports is left
enabled.

• Extend FIFO - when checked, extends the selected ports FIFO

buffer from 16 to 64 bytes.

• Receive Buffer - These settings allow the select ion of a

receiver FIFO tr igger setting. Selecting a low value will allow
the inter r upt to be serviced quicker, which is good for slow
machin es . If you have a fast machine, setting a high value will
give you more time for multi-tasking operations.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 56

• Transmit Bu ffe r - T hese set tings allow the selection of a

tran smitter FIFO trig ger se tting. S electing a low valu e w ill
send fe we r da ta-bytes per interrup t, and this is recommen ded if
you are communicating to a slower machine. Selecting a high
value will send more data-b ytes p er interrupt, and w ill give
mor e time for multi-tasking operations.

10. Automatic Hardware Flow Control. One of two options may

be selected:

• Off (De fault) - This w ill turn off au tomatic flow contr ol. (If

you hav e no data transfer p roblems then se lec ting this op tion is
fine.)

• RTS/CTS - This will us e the R TS a nd CTS lines for automatic

hardware flow contro l.

11. 485 Mode offers the options:

• Half Duplex / Full Duplex(default) - are used in conjunction

with the RS485 Multiplex Jumper Settings.

NOTE: These software sett ings must match the RS485
Multiplex Jumper configur ation , as described in the
section “RS485 Multiplex Jumper Settings” in
Chapter 2, to ensure accurate and error free dat a
tr ansmission.

• CTS Hold True, determines whether the CTS handshake

signal is INPUT from the external serial device or is
permanently forced t r ue on the card. The serial ports o wn RTS
OUTPUT handshake signals are always taken out to the serial
port connector .

12. Restore - when this button is clicked the settings in the current

win dow w ill b e rese t to the d efa ult values of:

Enable FIFO: On (Checked)
Extend FIFO: Off (Unc he c ked)
Receive Buffer: 3

rd

fr om left.

T rans mit Bu ffer: 16

Automatic Hardware

flow Control: Off
485 Mode: Full duplex.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 57

Windows NT 4.0 Installation.

Micro so ft Windows NT Provides built in support for 255 st andard
serial ports. To setup your PCI RS232/422/485 serial card you
should follow these steps. P lease note that to change any kind of
hardware configur ation under Windows NT you must be logged in
as a us er w ith Adminis tr ator level priv ileges, if you do not have
these please contact your system administrat or.

Software Installation.

Insert the PCI Velocity RS232/422/485 into your PC, as described
in chapter 2, and rest ar t. Place the supplied CDROM titled “Serial
Solutions Software” in a suitable drive and from the Star t Menu
choose Run and enter

<drive>:\diskimg\ssnt\setup (where <drive>: is the
path to the CDROM drive containing t he installation disk).

• I nstallShield will then install the dr iver softw are automa tically

- it will then c opy the necessary files and st ar t itself. This
auto matically detect s your new PCI ser ial card(s) and does not
require any further system restarting.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 58

Examining Card Configuration.

Go t o Control Pa nel (Start /Se ttings/ Control P anel) and double
click on Serial Solutions PCI:

You will be p resented with a S erial Solution s P CI P or t
Configuration window:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 59

Configuring Ports .

To view the sett ings of a port , select it and click on set tings, 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 maximum value available is 921,600 (1
Megabaud.) Note: Ma ny serial comms applica tions will not
actually regist er the port s as running at baud rates of above

115200.

2. Data Bits.

3. Parity.

4. Stop Bits.

5. Flow Control.

6. Advanced - see t he sect ion below, titled “Advanced Port

Settings.”

Change to suit remote device.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 60

7. Restore Defaults - when clicked, resets t he selected COM por t

to the follow ing value s:

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 dialo gue is displayed:

Settings available in this window are:

1. FIFO settings.

• Use FIFO Buffers - t urns the selected ports FIFO buffer on or

off. It is stro ngly reco mmended t hat the FIFO for bo th ports is
left enabled.

• Receive Buffer - These settings allow the select ion of a

receiver FIFO tr igger setting. Selecting a low value will allow

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 61

the inter r upt to be serviced quicker, which is good for slow
machin es . If you have a fast machine, setting a high value will
give you more time for multi-tasking operations.

• Transmit Bu ffe r - T hese set tings allow the selection of a

tran smitter FIFO trig ger se tting. S electing a low valu e w ill
send fe we r da ta-bytes per interrup t, and this is recommen ded if
you are communicating to a slower machine. Selecting a high
value will send more data-b ytes p er interrupt, and w ill give
mor e 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 (De fault) - This w ill turn off au tomatic flow contr ol. (If

you hav e no data transfer p roblems then se lec ting this op tion is
fine.)

• RTS/CTS - This will us e the R TS a nd CTS lines for automatic

hardware flow contro l.

3. 485 Mode (available on the 485 port ) offers the opt ions:

• Half Duplex / Full Duplex(default) - are used in conjunction

with the RS485 Multiplex Jumper Settings.

NOTE: These software sett ings must match the RS485
Multiplex Jumper configur ation , as described in the
section “RS485 Multiplex Jumper Settings” in
Chapter 2, to ensure accurate and error free dat a
transmission.

• Force CTS True, determines whether t he CTS handshake

signal is INPUT from the external serial device or is
permanently forced t r ue on the card. The serial ports o wn RTS
OUTPUT handshake signals are always taken out to the serial
port connector .

4. Defaults - When clicked this button resets t he advanced

properties to the followed settings:

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 62

Use FIFO Buffers: On (checked)
T rans mit Bu ffers: 1
Receive Buffers: 8
Use Extended FIFO: Off (Unchecked)

Automatic Hardware

Flow Control: Off
485 Mode: Full Duplex

Uninstalling Serial Solutions PCI.

T o unins tall Ser ial Solu tions P CI:

• From C ontrol Pa n el, open the Add /R emov e Pr ogra ms a pple t,

then close the Contr ol Panel.

• Select from the list Serial Solutions PCI.

• Click the Add/R e move bu tton.

Windows NT w ill then unins tall the S erial Solution s P CI a pplet
without the need for restarting.

PCI Velocity RS232422/485 Software Setup

Chapter 3 Page 63

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 64

Chapter 4

RS232 PINOUTS AND PORT

CABLING.

Introduction.

This chapter gives details of the 9 and 25 pin RS232 pin outs,
cabling and connections, with information on how to connect the
serial por ts of tw o PCs and how t o make a selftest loop back
connecto r .

The RS232 Standard.

The RS232 standard is ancient in computer industry terms.
Intro duced in 1962, it is now widely established. RS232 is a slow
speed, sho r t distance, single ended t r ansmission system (i.e. only
one wire per signal). Typical RS232 maximum cable length is 50
feet with a maximum data rate of 20K bits per second.

Figure 4-1. RS232 Point To Point Connection.

RS232C Standard

1 Driver 1 Receiver

Line Length Max D ata Rate

50 Feet = 15m 20 Kbits/sec

DTTL

Ground Ground

TTLR

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 65

Serial Port Pin Outs.

The pinou ts of t he 9 pin Ma le D connectoris g iven below.

Figure 4-2. Serial Port RS232 Pin Outs.

9 Pin D Serial Port RS232 Cables.

To connect to the AT style RS232 Serial Port you will need a cable
terminating in a 9 way female D connector . It is sound practice to
use ca bles w ith screws fitted th at will allow you to fa sten the cab le
securely to the PC card.

I n genera l, you will need to mak e up a “cross ov er” ca ble to
corr ectly interface the PC to the RS232 port of another co mputer
or device. Traditionally, making up the cross over cable has been
considered a black art. Ho wever, pr ovided you have the pin outs
and handshake requirements o f both sides of your RS232
connection, t he cross over cable beco mes a matter of common
sense. The cross over cable is simply to ensure that the right
signals going out o f one RS232 port go into t he appro pr iate lines
of the other RS232 po r t.

PIN 1 - DAT A C ARR IE R DETE C T (DCD )

P IN 6 - D ATA SE T R EAD Y (DS R)

PIN 8 - C LEAR TO S EN D (CTS)

PIN 3 - TR AN S M ITTE D DATA (TXD)

PIN 2 - RECEIVED DATA (RXD)

PIN 4 - DAT A TE R M INAL R E ADY (DT R )

PIN 7 - REQUES T T O S END (R TS )

PIN 9 - R ING INDIC AT OR (R I)

PIN 5 - GR OUN D (GND )

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 66

9 Pin D Serial Port Connection To Another PC.

Suppose we want t o connect the AT style 9 pin D Serial Port to the
serial po r t of another IBM PC. See Figure 4-3.

1) Connect the earth lines.
Line 5 of Serial Port 2 to lines 1 & 7 of the other PC.

This gives the two devices a common earth level.

2) Connect the Transmit and Receive lines together.
Line 3, TXD, Port 2 goes to line 3, RXD, of the other PC.

Line 2, RXD, Port 2 goes to line 2, TXD, of the other PC.
This allows each to receive the data transmitted by t he other.

3) Connect t he Por t 2 DTR line, pin 4 to the other PC DCD, pin 8
and CTS, pin 5, lines.
Also, connect up the other PC DTR line, pin 20 to t he Port
2 DCD, pin 1 and CTS, pin 8, lines.

This allows the receiving device to signal when it can no
longer accept data. The receiving device sets DTR false when
it is unable to r eceive any more data. The sending device reads
DTR on its CTS and DCD pins. It sho u ld stop sending when
CTS go es false.

4) Co nnect the Port 2 RTS line, pin 7, t o the other PC DSR line,
pin 6. Also, connect the o ther PC RTS line, pin 4, t o the Po r t 2
DSR line, pin 6.
T his RTS lin e is used to let the oth er d evice know that it is
ready for data exchange.

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 67

Figure 4-3. 9 Pin D Serial Port To Other PC Cable.

AT SERIAL PORT Side Other PC SERIAL PORT Side.
9 PIN D CONNECTOR

9 PIN D CONNECTOR

5
3
2
7
6
4
8
1

5
2
3
6
7
1
8
4

1

2

3

4

5

6

7

8

9

5

4

3

2

1

9

8

7

6

ACTUAL REPRESEN TATION:

SCHEMATIC REPRESENTATION:

9 PIN D CONNECTOR 25 PIN D CONNECT OR

5
3
2
7
6
4
8
1

SCHEMATIC REPRESENTATION

ACTUAL REPRESENTATION

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 68

9 Pin D Serial Port To A Modem.

If you are connecting a MODEM to a 9 pin D Serial Po r t then you
will NOT need a cross over c able a nd a s traig ht through c able
connected as the 9 to 25 pin adapter given in Figure 4-5.

9 Pin D Serial Port Loop Back Connector.

A loo p back connecto r can be used to echo RS232 data tr ansmitt ed
by a serial port back into its o wn RS232 receiver. In this way, the
function o f the serial por t can be tested.

For an AT style Serial Port use the a female 9 way connector wired
as in Figure 4-4.

Figure 4-4. 9 Pin D Serial Loop Back Connector.

9 PIN D CONNECTOR 25 PIN D CONNECT OR

3
2
7
8
6
1
4

20

8

6

5

4

3

2

SCHEMATIC REPRESENTATION:

ACTUAL REPRESENTATION:

PCI VelocityRS232/422/485 RS232 Pinouts & Cabling

Chapter 4 Page 69

Figure 4-5. 9 To 25 Way Adapter.

This adapter cable makes the AT style 9-pin serial port , loo k like
the standard PC 25 pin serial port . I t is NOT a cross over cable!

9 Pin AT SERIAL PORT 25 Pin PC SERIAL PORT

9 P in Female D C onnector

25 Pin Male D Connector

5
1
2
3
4
6
7
8
9

AC TU AL REPR ESENTA TI ON:

SCHEMATIC REPRESENTATION:

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 70

Chapter 5

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 car r ied 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 rat e is 100 Kilobytes per second. A
120-Ohm resistor should be used to ter minate the receiving end of
the line. It is generally used between one transmitter receiver pair
to ONLY one other t r ansmitter receiver pair, but each ou tput can
drive up to 10 receivers.

RS422 Standard

1 Driver up t o 10 Receivers

Line Length Max D ata Rate

40 Feet = 12m 10 Mbits/sec

400 Feet = 122m 1 Mbits/sec

4000 Feet = 1219m 100 Kbits/sec

D

R

TTL TTL

The RS485 Standard.

The RS485 standard is similar to the R S422 standard upo n 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 t er minate either end of the main line. If more

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 71

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 Dr iver/Receiver Pairs

Line Length Max D ata Rate

40 Feet = 12m 10 Mbits/sec

400 Feet = 122m 1 Mbits/sec

4000 Feet = 1219m 100 Kbits/sec

DD

R

R

R

Terminating Impedance’s.

RS422 and RS485 lines should be ter minated at the end of the
main branch of the RECEIV E R, in the cables character istic
imp edance. T hese t er minating 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 Por t
RS422/485 and AT Velocity RS422/485 cards have the correct
120 Ohm (nominal) ter minating resistors for t he RXD twisted pair
line and the CTS twisted pair line fitted o n t he RS422/485 card for
both t he serial ports o n t he 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
auto matically provided by the on board resisto r s and do no t have
to be added by the user.

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 72

Fail Safe Ope n Circuit Detection.

Open circuit is when there are no drivers on the circuit. T his
occurs by design in party line multi driver/receiver systems and
unintentionally when the t wisted pair line is accidentally cut o r
disconnected or the tr ansmitting device fails. In RS485 party line
systems t here are extended periods of time when none of the many
possible talkers are gat ed onto the bus. This is known as t he line
idle state and o ccur s when all the driver outputs ar e in the high
impedance st ate. 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 ar e detected
by the receivers, either co r r upting good communications or
causing noise to masquerade as good data.

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

Fail Safe Short Circuit Protection.

Short circuits are when the two lines of a twisted pair are
connected together. This occurs due t o either accidental damage to
the cable or due to failure of one or more transmitt er / r eceivers on
the line. The short circuit condition is dangerous since damage to
the receiver may occur and co mmunication may be corrupt ed or
prevented.

The on board fail safe short circuit det ection prevents the line
impedance from going to zero and t hus pro tects the inputs o f
receivers and the ou tputs of drivers.

RS422 Operation.

Generally, in RS422 systems all 8 signal lines from the 9 pin D
connector par ticipate in the data tr ansfer sequence, thus 4 twisted
pair cables are used. One twisted pair carries t he TXD data
out war ds, one pair brings the RXD data inward, another pair
carries the RTS handshake outwar ds and t he fourt h pair brings the

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 73

CTS handshake inwards. There is no need to carr y the gro und from
one device to anot her.

This RS422 arrangement allows data t o be transmitted and
received simultaneously since each signal has its own dat a cable
pair. In addition, t he receiver can set RTS true so telling the
transmitter o n its CTS input that the receiver is ready to accept
data. I n this way, no data will e ver b e tra nsmitted when th e
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 t ype 8795 may also be used in less
noisy environments.

The on board resistor netwo r ks terminate t he receiving end of the
twisted pair cable in its characteristic impedance.

Figure 5-1. 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

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 74

Note:

i.) Receiver ends terminated in charact er istic impedance

ONBOARD resisto r net works.
ii.) USE BE LDEN T YPE 9729 etc. see above.
iii.) RS485 Gating & Multiplex Jumpers as Factor y Set.

RS485 Operation.

The RS485 standard is int ended 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 correct ly in bot h RS422 and RS485
systems. The main difference therefore is in how the system is
implemented. T hough t he 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 t wo wire, Half-Duplex configur ations the TXD+ line
is connected to the RXD+ whilst t he 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 syst ems are handled by a software proto col in
RS485 syst ems. In sit uations where more t han one device may
transmit data on t he shared data line, each cards RTS line is used
as a gating signal to enable the TXD driver o nly when that card
needs to transmit data, i.e. set TX D GATE or AU TO jumper. T his
mechanism prevents bus co nt ent ion caused by multiple
transmitters holding the line in oppo sing stat es. Revision 3 and
higher versions of this c ard h ave a facility which automatically
“gates” the RTS line, thus enabling the transmitter independently
of a n y software. This “ Auto g ating” is de sc ribed in more deta il 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.)

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 75

RS485 Cable.

For bes t noise immunity use twisted pair cables to mak e the R S485
connection. In Half Dup lex wiring only 1 tw isted cable pair is
needed. Two twisted pair cables are needed for Full Duplex
comm unications.

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 t he t w isted 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.

RS485 One Talker - Many Listeners, Half Duplex.

There are several schemes for connecting RS485 devices
depending on the character istics of the system. In many cases there
will be only one d evice , which ca n tr ansmit, data and all the others
simply lis ten to it. T his scheme is us ed for theatr ica l lighting
intensity contr ol in t he DMX512 standard. This is shown in Figure
4-2, below. For t he t alker the RS485 TXD GATE jumper should
r ema in in th e factor y se t position, i. e. tra nsmitter is always
enab led. T here 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 5-2. RS485 1 Talker Many Listeners.

Note: The Receiver end of MAIN line terminated in charact er istic

imp edance by ONBOARD resisto r net works, stubs off the main
not terminated.In the above scheme, o ne RS485 device is talk
only, it tr ansmits data, but it does not r eceive any. The other
RS485 devices are receive only, they do not tr ansmit any data at
all. Figure 5-3 gives the RS485 Gating jumper sett ings.

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 76

Figure 5-3 Half Duplex Settings of RS485 M ultiplex

• Bot h 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 Fig ure 5-4 , b elow. T his is also known as
“party lin e” tr ansmis sion. It is impera tive to have some method of
preventing tw o devices tr ying to drive the data lines at the same
time. The nor mal method is to use the RTS line as a talk enable.
T he RTS line should g o tr ue immediate ly prior to the data
tr ansmis sion and g o fals e immediately after th e last b yte in the
stream is sent. S ee Figure 5-3 for jumper settings.

Figure 5-4. 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 charact er istic
imp edance, stubs off main line not impedance, since bot h ends
receive. The t wisted pair ends are wired t o both RXD+ & TXD+
and RXD- & TXD- at each RS485 device!

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 77

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 contr ol available on t he PC, usually due to the use
of a third party communications program that prevents the use o f
the RTS signal as a “transmit enable” cont r ol, via the TXD GATE
jumper. It can be used in the following situations:-

a) The PC is connected to only ONE RS485 device.
b) T he 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 respo nding to request s fro m the PC to send data.
In effect, the RS485 device’s address and the command it

receives is used to contro l access to the devices TXD channel.
T his is a Fu ll Duplex system. Two twisted pair c ables are req uire d.
One twisted pair, is the PC’s TXD channel, it carries the data sent
from the PC’s TXD out puts to the RXD inputs of each of the
RS485 devices. The second t wisted pair, is the Devices TXD
channel, it carries the data sent from each of the devices’ T XD
outputs to the RXD inputs of the PC.

The advantages of this system are great, since no new
communications, so ftwar e is needed, and the PC can talk and listen
at the same time. In effect, the handshaking is performed by the
intellig ence of the RS485 devices att ached t o the PC.

When wired as in Figur e 5- 6 below, t he 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. t r ansmit dat a, at any
one time. Each RS485 device recognizes commands and data
addr es se d to it, it only talk s w hen the P C c ommands it to do s o.
When the RS485 device receives the command to talk from the
PC, it gates its TXD drivers on, sends the data down t he device

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 78

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

Figure 5-5. RS485 Jumpers, Full Duplex.

• Bot h jumpers left unconnected (not sho r ted).

Figure 5-6. RS485 Full Duplex.

Note: The receiver end of MAIN line ter minated in characteristic

imp edance, stubs off the main not terminated.

Optional Grounding Arrangements.

Prop er operation of the cable circuit, according to TIA EIA: 485 A
(1995) requires that t he cable ground shield is not connected
direc tly to the e quip ment ground shield. A cu rrent limiting resistor
should be used in series with the shield to avo id possible large
current flow due to differ ences in grou nd potential. Any one of the
methods shown in Figure 5-7, below can do t his.

PCI VelocityRS232/422/485 Additional RS422/485 Operati on

Chapter 5 Page 79

Figure 5-7 - Optional Grounding Arrangements For
A PCI RS422/485 Card.

Co nfigur atio n A)

Co nfigurat ion 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 prot ective gro und
directly together when specific installation co nditions necessitat e.

GWG

SG

GWG

100Ω

(1/2)

SG

SG = Signal Ground Interchange circuit.
GWG = Gr een wire groun d of power system.

= P rotective grou nd of frame groun d.

= Circuit grou nd or circuit

Index

1 Megabaud ...............................................................................11

115200 Baud.............................................................36, 40, 50, 54

16450 / 16550........................................................................ 7, 11

460800 Baud.............................................................36, 40, 50, 54

921600 Baud.............................................................36, 40, 50, 54

adapter................................................................................. 68, 69

asynchronous.............................................................................11

Autogating ........................................................................... 11, 12

baud / baud rate ........................................................................ 8, 9

BBCARDS.EXE............................................................ 18, 21, 23

Belden........................................................................................ 74

bits................................................................................. 15, 64, 72

buffer.........................................................................................73

Buffer.........................................................................................21

buffer / buffered................................................................. 7, 9, 11

cable.............................9, 15, 16, 64, 65, 68, 69, 71, 72, 73, 74, 75

Changing COM numbers in Windows 95............................. 34, 48

command ............................................................................... 8, 77

Configuring Ports In Microsoft Windows NT. ............................ 57

connectors ............................................................................ 16, 65

cross over....................................................................... 65, 68, 69

CTS ................................................................8, 11, 66, 71, 73, 74

data word le ngth......................................................................... 11

DCD ......................................................................................8, 66

device driver .................................................................. 18, 19, 21

DSR....................................................................................... 8, 66

DTR ....................................................................................... 8, 66

emulation.....................................................................................8

fail safe ...................................................................................... 72

FIFO ...................................................................................... 7, 11

gating.........................................................................................74

handshake.................................................................... 7, 8, 65, 72

impedance...............................................71, 72, 73, 74, 75, 76, 78

installation ....................................................................... 9, 15, 18

Installing Ports In DOS. .............................................................18

Installing Ports In Microsoft Windows 95 & 98.......................... 29

Installing ports in Windows 3.x.................................................. 24

interrupts......................................................................................9

jumper.................................................................74, 75, 76, 77, 78

last ............................................................................................. 76

loop back.......................................................................... 9, 64, 68

Maximum Baud Rate ........................ 35, 36, 39, 40, 49, 50, 53, 54

mode...................................................................................... 8, 78

open circuit ................................................................................ 72

parity........................................................................................8, 9

party line.............................................................................. 72, 76

pin outs................................................................................ 64, 65

port / ports..................7, 8, 9, 11, 15, 18, 57, 64, 65, 66, 68, 69, 71

Port Address...............................................................................21

protocol.................................................................................. 8, 74

receive ..........................................................14, 66, 75, 76, 77, 78

resistor......................................................................70, 73, 74, 75

RS232.......................................................7, 11, 14, 15, 64, 65, 68

RS422 / RS485............................11, 12, 14, 42, 56, 61, 70, 71- 78

RS422 Pinout............................................................................. 13

RS485 Multiplex Jumper Settings.................................. 42, 56, 61

RTS .............................................. 8, 11, 66, 71, 72, 73, 74, 76, 77

RXD ........................................... 11, 14, 66, 71, 72, 74, 75, 76, 77

serial port.............................. 7, 8, 9, 15, 18, 57, 64, 66, 68, 69, 71

shared int errupt......................................................................9, 10

short circuit................................................................................ 72

SISR .......................................................................................... 19

speed.................................................................................... 11, 70

stop bits...................................................................................... 15

technical.....................................................................................10

twisted pair .............................................14, 71, 72, 73, 75, 76, 77

TXD..................................................11, 14, 66, 72, 74, 75, 76, 77

Uninstalling Serial Solutions PCI fo r Windows NT.................... 62

Windows............................................................................ 7, 9, 57