2 Channel Serial Communications Board User Manual
Contents
1. terit exer RESELLER ANARAN RA 4 2 0 START P GUDE ntn ttis RSS 5 2 1 Gomputer bad GERE 5 2 2 Backing up the Software 5 5 2 3 Selecting the Correct Comms Port Addresses 6 2 4 Installing the CA A iinan aias 7 2 5 Making the Right Connections sees 8 2 6 The Software 8 3 0 CONNECTING CHANNEL A AND 9 3 1 Connecting to a Serial 9 3 2 Connecting to a Modem rnnnnnnnnnnnnvrrrnnnnnnnnrrnnrrrnnnnnnnnernnnnrrnnnn 9 3 3 Connecting to Another SIO 2 10 3 4 Connecting a 10 4 0 CHANNEL B ALTERNATIVE 5 11 4 1 RS422 Full Duplex Mode 11 4 2 5485 Half Duplex 11 4 3 85485 Multi Drop Network Mode 12 4 4 20 Milliampere Current Loop 12 5 0 THE SIO 2 AND 13 6 0 COMMERCIAL DATA ACQUISITION PACKAGES 13 APPENDIXA tate tete teet S2. tee 25 APPENDIX Lits ter pd Rede ue ER RR aa 26 Channel B RS422 485 Full Duplex Mode 26 APPENDIX M cincti tete 27 Channel B RS422 Full Duplex Connections 27 to Another SIQ 2 iiit erecto etie ete LEER ERRARE 27 APPENDIX ee L 28 Channel B RS485 Half Duplex Mode 28 Multi Drop Mode rnnnnrrnnnnnnnnnnnnnnrrnnnnnnnnnnnnnnnrnnnnnnnnnrnnnnnrrnnnennnnnn 28 APPENDIX 29 01270001 doc Blue Chip Technology Ltd Contents 85485 Half Duplex Connections to Another SIO 2 29 APPENDIX eere decies nemi edidere 30 85485 Multidrop Network up to 32 SIO 2 30 can be eese up rae nana rae RR Re Rr Re 30 APPENDIX ttem et rt i ee eee 31 Interrupt Link Setting for Channels and B 31 APPEND R as E E 32 PO XT AT Port Map NE 32 VO Address 32 APPENDIX S 33 PC XT Interrupt nnn 33 34 Interrupt Map EE EE 34 APPENDIX V 5 deter 35 SIO2TEST BAS Test 35 AP
3. Digital Ground bbdddddddod Tt ttt RCLD Current Loop OR B Ful Half Duplex TX RTS RS232 Full Duplex RX INPUT RS232 TX Output RS232 RX Full Duplex DE 14 m 01270001 doc Blue Chip Technology Ltd Page 20 Appendix G Page 21 APPENDIX G Channel B R232 Full Duplex Mode D25 Connections RI Input DOD Input DTR Output Digital Ground DSR Input CTS Input RTS Output RX INPUT TX Output _ di Link Positions P Blue Chip Technology Ltd 01270001 doc Page 21 Page 22 Appendix H APPENDIX H Connecting Another DTE Device to the SIO 2 Channel B A Null Modem Cable D25 Connections SIO 2 E __ Printer or Second SIO 2 TX Output RX Input 2 3 RX Input TX Output 3 RTS Q RTS 4 Digital Ground Digital Ground 7 DCD Q 9 DTR 20 DTR DCD 8 Page 22 01270001 doc Blue Chip Technology Ltd Appendix I Page 23 APPENDIX I Channel B 20mA Current Loop Mode D25 Connections RCLR 4 TCLR Q TX TOLD Q RCLD OG Oo Oo er Link Positions LKD e 1234 5 6 LKH LKH 1 Optional i Optional We om DD LKJ 1 LKJ 1 EE run 2 Eun On RX On TX 2 Blue Chip Technology Ltd 01270001 doc Page 23 Page 24 APPENDIX J App
4. 008H 010H 020H 040H 080H 100H 200H I m O Io OJ OOO lO IN 290 HEX OOO OLODODO 008H 010H 020H 040H 080H 100H 200H 008H 010H 020H 040H 080H 100H 200H lo m x OOOO lo 00 pi m x OIOIO N B ALL LINKS VIEWED WITH CONNECTORS ON RHS 01270001 doc Page 17 Page Page 18 Appendix D APPENDIX D Channel A RS232 Only D9 Connections J Digital Ground RI CTS RTS DSR DTR TX Output RX Input DCD TITT 18 01270001 doc Blue Chip Technology Ltd Appendix E Page 19 APPENDIX E A D25 Pin to D9 Pin Adapter DTE D25 And D9 Pin Connections D25 D9 DCD DCD 8 1 RX Input RX Input 2 TX Output 0 TX Output DTR Q O DTR Q Q 4 Digital Ground Digital Ground 76 5 DSR O QO DSR RTS Q Q RTS CTS Q Q CTS RI RI 22 9 Blue Chip Technology Ltd 01270001 doc Page 19 Page 20 Appendix E APPENDIX F Channel B RS232 422 485 Current Loop D25 Connections E a RCLR Current Loop OO TCLR Current Loop RI RS232 TCLD Current Loop DCD RS232 DTR RS232
5. Class A amp B Immunity EN 50082 2 1995 incorporating Electrostatic Discharge IEC 801 2 1991 Performance Criteria A Radio Frequency Susceptibility 50140 1993 Performance Criteria A Fast Burst Transients IEC 801 4 1988 Performance Criteria A Page 4 01270001 doc Blue Chip Technology Ltd Start up Guide Page 5 2 0 START UP GUIDE 2 1 Computer Type The SIO 2 Communications card is designed to work with all correctly engineered PC compatible computers that can provide one standard 8 bit IBM PC compatible I O slot If your machine has two processor clock speed options we suggest that you perform the installation tests of the SIO 2 with the machine in slow speed mode Once correct operation of the card has been established the perform the same tests at the higher clock rate Unfortunately although Blue Chip Technology makes every effort to test its products in a wide range of machines we cannot guarantee that every so called PC compatible has correct I O slot timing Some of the latest 80386 based machines have a facility in their CMOS RAM set up program to adjust the number of wait states used by the machine when accessing the I O slot 2 2 Backing up the Software Disk The SIO 2 card has been supplied with a floppy disk containing software demonstrations and example drivers for your use It is important that you make an immediate backup of this disk and store it in a suitably cool dry place The di
6. O o 5 6 CAN BE FITTED TO ENABLE THE 1008 TERMINATOR Q RESISTORS IN THE RX AND TX LINES RESPECTIVELY LKE FUL HLF oe N B LKC NOT APPLICABLE Q Q BX Twisted Pair OGL a Q s M Twisted Pair her 1 Page 26 01270001 doc Blue Chip Technology Ltd Appendix M APPENDIX M Channel B RS422 Full Duplex Connections to Another SIO 2 D25 Connections 510 2 510 2 P Q 9O A Sheilded Twisted Pair 7 X E a Q 5 587 s Q Sheilded Twisted Pair i i m 17 g Ls Ore Link Positions Page 27 Sheilded Twisted Pair Sheilded Twisted Pair LKD NB FIT LKD 5 AND OR 6 TO ENABLE 1000HM RESISTORS R3 AND R4 TO OO e TERMINATE CIRCUIT 2 Blue Chip Technology Ltd 01270001 doc 27 Page Page 28 Appendix N APPENDIX N Channel B RS485 Half Duplex Mode Multi Drop Mode D25 Connections Link Positions LKD OOOO ha 1 2 3 4 5 6 O E 0 Q O FUL HLF e Q TS e OUT1 e _ DTR 8 DTR FIT TO SELECT SWITCHING SIGNAL O mp Twisted Pair o NE 0 o 14 her Page 28 01270001 doc Blue Chip Technology Ltd Appendix O Page 29 APPENDIX O RS485 Half Duplex Connections to Another SIO 2 D25 Connections 510 2 510 2 Sheilded Twisted Sheilded Twisted Pair Link Positions On Bo
7. from incorrect operation of the card Channel B is also configured as a DTE device A full set of connection details for ever mode of operation appears in the Appendix If installing the SIO 2 card in an Amstrad 1512 or 1640 it may be necessary to remove the bottom retaining screw on the 25 way D type connector This is due to a non IBM standard back panel on the Amstrad Blue Chip Technology Ltd 01270001 doc Page 1 Page 2 Specifications 1 0 SPECIFICATIONS 1 1 Electrical Specification Number of Channels Interface Standards ANTES A RS232 Channel B RS232 65422 85485 20mA Loop 5V D C 150mA 500mW 1 2 Physical Specification Width Page 2 01270001 doc Blue Chip Technology Ltd Specifications Page 3 Electromagnetic Compatibility EMC This product meets the requirements of the European EMC Directive 89 336 EEC and is eligible to bear the CE mark It has been assessed operating in a Blue Chip Technology Icon industrial PC However because the board can be installed in a variety of computers certain conditions have to be applied to ensure that the compatibility is maintained It meets the requirements for an industrial environment Class A product subject to those conditions e The board must be installed in a computer system which provides screening suitable for the industrial environment e recommendations made by the computer system manufacturer supplier must be complied with regarding e
8. interface Data transmission rate is improved from 38 4 Kilobaud up to 10 Megabaud the transmission distance is increased from 15 metres to 1 Kilometre and the circuit operates in a differential mode and does not require a common ground connection Note The transmission rate and distance are mutually exclusive The natural progression for RS422 was for it to grow into a network communications medium As far as point to point communications are concerned see figure 1 RS422 is a success due to the possible high speed and long distances However when the true bus topology network figure 2 was considered the standard RS422 transceivers could not cope with the possibilities of more than one transmitter being active at any one time Figure 1 Computer A Computer B ni EL II LL ha LE Blue Chip Technology Ltd 01270001 doc Page 37 Page 38 Appendix x Figure 2 Computer Computer Computer Up to 32 1 2 3 If this situation did occur the RS422 drivers would probably be irreparably damaged To overcome this the RS485 standard was established This allows for the possibility of a transmission collision from any two computers without any damage occurring The RS485 is now the industry standard for low cost Collision Sensing Multiple Access networks CSMA and the most popular device for implementing this circuitry is the 75176 transceiver as used on the Blue Chip Technology SIO
9. the 25 way D connector on the rear panel as a standard IBM PC style RS232 and current loop port and also has RS422 and RS485 capability Both channels can be used to connect various peripherals such as printers modems and mouse type pointing devices 3 4 Connecting to a Serial Printer When IBM designed the PC they considered it to be a data TERMINAL and so the serial port design is treated as a TERMINAL or DTE device The consequence of this is that to connect it to another peripheral such as a printer you must reverse the signals between the two devices When connecting a serial printer it is necessary to remember to connect the printer busy line normally pin 20 on the 25 way D connector on the printer to the DSR CTS and DCD connections on the appropriate connector on the PC The wiring diagram for a suitable cable appears in Appendix H 3 2 Connecting to a Modem The connections for this type of equipment should normally be direct signal to signal and in the case of the WS4000 the following pins will make the modem behave correctly Blue Chip Technology Ltd 01270001 doc Page 9 Page 10 Connecting Channel A and B 25 way D connector Data terminl read Digital ground If you wish to use modem on channel the details of a D25 to D9 converter cable appear in Appendix E Alternatively you can create a special direct cable from the information in the pinout details 3 3 Connecting to Another SIO 2 Card The nul
10. 2 The electrical details of the RS485 standard are 1 Differential Drive the two outputs are driven to opposite polarities at any one time The maximum difference between the output pins at any time is 6 volts and the minimum is 2 volts 2 The input can accept up to 12 volts without any damage being sustained 3 The ability to drive up to a total of 32 transceivers connected at any one instant further transceivers can be accepted by using repeaters 4 The receiving sensitivity is 200 millivolts difference between the inputs pins Page 38 01270001 doc Blue Chip Technology Ltd Appendix X Page 39 5 7 volts to 12 volts bus common mode range permits a ground difference of 7 volts between devices on the bus Considerations 1 It is recommended that termination is applied to the devices at each end of the bus This termination is typically 100 ohms this is provided on the SIO 2 card and can be effected by fitting links on the card see the manual although it depends on the characteristic impedance of the cable being used m 9 qucm T An alternative method of termination can be implemented as below ve Ov This can be effective under certain conditions but does provide a path between the power rails on the devices Blue Chip Technology Ltd 01270001 doc Page 39 Page 40 Appendix x 2 The layout of the bus topology is subject to a phenom
11. MOS386 do allow the user to make use of more than 2 serial ports for the connection of estra user terminals and other printers etc and it is expected that OS 2 will do the same Many language compilers have the facility to use add on communications toolkits such as the Greenleaf comms library for etc The card uses the national Semiconductor NS16450N device which is functionally equivalent to the original Intel 8250 device used on the early PC serial cards and is the same chip used by most PC manufacturers today The floppy disk which accompanies the card contains a number of programs as examples of how to drive the COM ports from different languages There is a file called README TXT on the disk which details the latest updates to the programs 6 0 COMMERCIAL DATA ACQUISITION PACKAGES The Blue Chip Technology SIO 2 can be used with almost any data acquisition package that can transmit and receive information directly to and from a PC serial port or any package that has driver support for the INTEL 8250 or National Semiconductor NS164450chip The board is installable as a standard serial PORT in the following packages Blue Chip Technology SCAN1000 Blue Chip Technology Ltd 01270001 doc Page 13 Page 14 The SIO 2 and Software ASYST by Macmillan Software Labtech notebook LOTUS Measure LOTUS Symphony Almost any PC based communications package For more details about these packages and other PC data acquisition softw
12. PENDIX MW estiske Ban 36 Current Loop Simplex Connections to Another 510 2 36 OVGIVIGW EE EE NN ME 37 Blue Chip Technology Ltd 01270001 doc Outline Description Page 1 OUTLINE DESCRIPTION The SIO 2 card allows serial communications between computers printers plotters screen PID controllers instruments and any other device with a serial interface The frist channel is RS232 with programmable baud rate and word format The second channel is link selectable as either RS232 RS422 485 full duplex half duplex multi drop or 20mA current loop This gives compatibility with most standard serial interchange formats The SIO 2 is designed to provide a flexible solution to the problems of interfacing a PC or compatible with the following standards EIA RS232 V24 full or half duplex EIA RS422 full duplex EIA RS485 full duplex multi drop EIA RS485 half duplex multi drop 20 Milliampere current loop full duplex There are two channels designated A and B Channel A provides a normal RS232 type comms port and is connected to a 9 pin Cannon D range connector on the rear panel The pin out of this connector is to IBM 9 pin Serial standard and id configured as s DTE device Channel B provides a normal RS232 interface on the standard pins of a 25 way D connector but can also be selected to provide current loop RS422 and RS485 operation which all appear on different pin outs to provide some protection
13. SIO 2 2 Channel Serial Communications Board Blue Technology User Manual SIO 2 User Manual Document Part N 0127 0001 Document Reference 0127 0001 Doc Document Issue Level 0 6 Manual covers PCBs identified SIO 2 Rev C All rights reserved No part of this publication may be reproduced stored in any retrieval system or transmitted in any form or by any means electronic mechanical photocopied recorded or otherwise without the prior permission in writing from the publisher For permission in the UK contact Blue Chip Technology Information offered in this manual is correct at the time of printing Blue Chip Technology accepts no responsibility for any inaccuracies This information is subject to change without notice All trademarks and registered names acknowledged Blue Chip Technology Ltd Chowley Oak Tattenhall Chester Cheshire CH3 9EX Telephone 01829 772000 Facsimile 01829 772001 Amendment History Issue Issue Amendment Details Level Date 12 05 89 SEJ Update window front cover and logo See ECN 98 083 ET Contents OUTLINE 1 T O SPEGIFIGATIONS tratte OPI IPFE 2 1 1 Electrical 2 1 2 Physical Specification 2 Electromagnetic Compatibility 3
14. Software Redirected to INT OAH IRQ 2 Reserved Reserved Reserved Coprocessor Fixed Disk Controller Reserved Serial Port 2 Serial Port 1 Parallel Port 2 Diskette Controller Parallel Port 1 Appendix S 01270001 doc Blue Chip Technology Ltd Appendix V Page 35 APPENDIX V SIO2TEST BAS Test Connectors Test connectors to operate with SIO2TEST BAS can be made up by making the following links on dummy connectors D9 D25 2 3 2 3 4 6 4 5 7 8 6 8 20 7 25 14 16 15 17 18 11 Blue Chip Technology Ltd 01270001 doc Page 35 Page 36 Appendix W APPENDIX W Current Loop Simplex Connections to Another SIO 2 1st SIO 2 2nd SIO 2 Non Isolated Active Station Isolated Passive Station D25 Connections Data XMTR S C x 4100 Link Settings for Both SIO 2 Boards LKH T OYOOOO 1100 OLJOOOO 2100 12 3 4 5 6 Page 36 01270001 doc Blue Chip Technology Ltd Appendix X Page 37 Overview RS422 RS485 Most people have heard of RS232C as an interface standard used in computer communications The RS232C standard has been successful in uniting the industry to a common interface but it suffers from several limitations 1 Data transmission rate 2 Transmission distance 3 The need to connect the ground together unbalanced circuits RS422 was established in 1975 It overcomes the above problems and provides a fast reliable balanced
15. The SIO 2 may be placed in any available slot of your PC compatible computer provided that there 1s no restriction placed upon the slot be the manufacturer of the machine Blue Chip Technology Ltd 01270001 doc Page 7 Page 8 Start up Guide 2 5 Making the Right Connections Channel A of the SIO 2 is intended for RS232 DTE operation only Channel B is supplied with its links set for RS232 DTE operation If you wish to use any of the other options on the channel B then you should follow the link position and connection diagrams supplied in the Appendix and read the appropriate section of the manual The type of connection you will need to make to channel B of the SIO 2 will depend upon the interface on the peripheral device you wish to connect to 2 6 The Software Disk The card can be used as COMI or 2 in full duplex RS232 RS422 and current loop modes from most existing software but the RS485 half duplex mode requires the user to program the board to switch transmission on and off and for this mode of knowledge of programming in any of the PC languages is required The software disk supplied with the SIO 2 contains a number of example ways of driving the card from various languages Page 8 01270001 doc Blue Chip Technology Ltd Connecting Channel A and B Page 9 3 0 CONNECTING CHANNEL A AND B Channel A appears on the 9 way D connector on the rear panel as standard IBM PC AT style RS232 serial port Channel B appears on
16. are please contact Blue Chip Technology Whilst every effort has been taken to ensure that the information provided is accurate Blue Chip Technology cannot assume responsibility for any errors in this manual or their consequences Should any errors in this manual be detected the company would greatly appreciate being informed of them A policy of continuos product development is operated resulting in the contents of this document being subject to change without notice Page 14 01270001 doc Blue Chip Technology Ltd Appendix A Page 15 APPENDIX A Blue Chip Technology SIO 2 Rev C Blue Chip Technology Ltd 01270001 doc Page 15 Page 16 APPENDIX B Appendix B Standard Port Allocations for PC Serial Ports on LKA or LKB COM 1 HEX D OO 010H J 020H o4H D 040H JO O 100H aH 0 200H N B All links removed COM 3 HEX O 008H 010H 020H O 040H O 1O 100H O 200H Page 16 01270001 doc T m OLIO 0000 OKJOOOOO Blue Chip Technology Ltd APPENDIX C Standard Port Allocations for PC Serial Blue Chip Technology Ltd 17 Appendix C Ports on LKA or LKB 008H 010H 020H 040H 080H 100H 200H
17. arthing and the installation of boards e The board must be installed with the backplate securely screwed to the chassis of the computer to ensure good metal to metal i e earth contact Most EMC problems are caused by the external cabling to boards It is imperative that any external cabling to the board is totally screened and that the screen of the cable connects to the metal end bracket of the board and hence to earth It is recommended that round screened cables with a braided wire screen are used in preference to those with a foil screen and drain wire Use metal connector shells which connect around the full circumference of the screen they are far superior to those which earth the screen by a simple pig tail Standard ribbon cable will not be adequate unless it is contained wholly within the cabinetry housing the industrial PC Ensure that the screen of the external cable is bonded to a good RF earth at the remote end of the cable Blue Chip Technology Ltd 01270001 doc Page 3 Page 4 Specifications Failure to observe these recommendations may invalidate the EMC compliance Warning This is a Class A product In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures EMC Specification A Blue Chip Technology Icon industrial PC fitted with this card meets the following specification Emissions EN 55022 1995 Radiated Class A Conducted
18. control port B 070 07F RTC and CMOS RAM NMI Mask Write 080 09F DMA Page Register Memory Mapper Interrupt controller 2 8259 Clear NPX 80287 busy OF1 Reset NPX 80287 OF8 OFF Numeric Processor Extension 80287 1F0 1F8 Hard disk drive controller 200 207 Reserved 278 27F Reserved for Parallel Printer Port 2 2F8 2FF Reserved for Serial Port 2 300 31F Reserved 360 36F Reserved 378 37F Parallel Printer Port 1 380 38F Reserved for SDLC Communications Bisynchronous 2 3A0 3AF Reserved for Bisynchronous 1 3B0 3BF Reserved 3C0 3CF Reserved 3D0 3DF Display Controller 3F0 3F7 Diskette Drive Controller 3F8 3FF Serial Port 1 Page 32 01270001 doc Blue Chip Technology Ltd Appendix S Page 33 APPENDIX S PC XT Interrupt Map Number Usage NMI Parity 0 Timer 1 2 Reserved 3 Asynchronous Communications Secondary SDLC Communications 4 Asynchronous Communications Primary SDLC Communications 5 Fixed Disk 6 Diskette 7 Parallel printer Blue Chip Technology Lt 0127000146 Page _ 33 Page 34 APPENDIX T AT Interrupt Map Level Microprocessor NMI Interrupt Controllers CTLR 1 CTLR 2 IRQO IRQ 1 IRQ 2 IRQ 8 IRQ 9 IRQ 10 IRQ 11 IRQ 12 IRQ 13 IRQ 14 IRQ 15 IRQ 3 IRQ 4 IRQ 5 IRQ 6 IRQ7 Page 34 Appendix T Function Parity or I O Channel Check Timer Output 0 Keyboard Output Buffer Full Interrupt from CTLR 2 Realtime Clock Interrupt
19. endix J Current Loop Full Duplex Connection to Another SIO 2 1 1 Non lsolated Active Station Data XMTR Data RCVR D25 Connections Link ings for 1 10 2 ids Pm 2 2100 1 2 3 4 56 Page 24 01270001 doc 2nd SIO 2 Isolated Passive Station 4200 RCVR Data P225 P2 9 VA XMTR Data LZ 2 11 4100 ME Link Settings for 2nd SIO 2 090000 1686 09606666 2 OO 1 2 3 4 5 6 Blue Chip Technology Ltd Appendix K Page 25 APPENDIX K SIO 2 Current Loop Half Duplex Point to Point Connection to Another SIO 2 151 SIO 2 2nd SIO 2 Non Isolated Active Station Isolated Passive Station D25 Connections 2 11 P2n8 Data XMTR KD pe 7 74 RCVR Data 4100 pares 4200 P2 25 Data RCVR XMTR Data C pe 4200 y 4100 Link Settings for 1st SIO 2 Link Settings for 2nd SIO 2 16426000 faa iu oo OYOOOVO Fr OQoooo 2 OO TL 23 4 5 6 12 3 4 5 6 Blue Chip Technology Ltd 01270001 doc Page 25 Page 26 Appendix L APPENDIX L Channel B RS422 485 Full Duplex Mode D25 Connections Link Positions LKD uS
20. enon known as Transmission Line effects This can affect the signal strength at various points on the bus and if the distance from the true bus to the device is not kept as short as possible there is a distinct chance that null points extreme or low signal strength more likely will appear Spurs length to be kept as short as possible The ideal is where no spur stub length exists This can be achieved by connecting the bus and the joining device at the same point 3 Length of cable is determined by the transmission rate e g 1 Kilometre 100 Kilobaud 100 Metres 1 Megabaud 10 Metres 10 Megabaud Using 24 AWG cable 4 The cable used can affect the operation of the bus Typically it should present a nominal characteristic impedance of 100 ohms to frequencies greater than 100 kilohertz and a DC series loop resistance not exceeding 240 ohms Page 40 01270001 doc Blue Chip Technology Ltd Appendix X Page 41 Whether the cable is twisted or not screened or not can affect the operation Obviously by screening the cable the noise immunity can be increased but you should consider a Where is the screen attached to it is not advisable to connect the screen up to all devices remember RS232 b The cable to cable crosstalk within a sheath will increase c The cable tray capacitance will increase and if excessive depends on length of cable and value foot can affect performance The above should be consid
21. ered before a network is implemented 5 There should not be more than 7 volts difference between any two devices ground potential on the bus Beyond 7 volts the common mode range will be exceeded and the devices will not operate correctly One way to operate under these conditions is by introducing an isolating transformer in the output circuitry of the transceivers 6 Problems can be experienced when implementing a software protocol on a 2 wire bus As we have stated before no two transceivers can transmit at the same time Therefore a mechanism must exist so that each device knows when it can transmit freely The most common way of operation is the Master Slave method This is where one device on the network is deemed to be the Master and this device initiates all transmissions by communicating with each if the other devices in turn and offering it an opportunity to transmit This provides a relatively simple solution but means that the Master will have a high overhead in controlling the network Also devices needing to communicate to devices other than the Master carry a larger overhead and an additional software complication Blue Chip Technology Ltd 01270001 doc Page 41 Page 42 Appendix x A more sophisticated protocol is the Token Ring method which works by each device knowing which device is next on the bus ID number not by physical location and taking directly to it The communication occurs between each adjacent pa
22. et based addressing system N B Remember when using this mode to fit good quality shielded twisted pair cable and also to install the links LKD5 and LKD6 for the 1000hm terminating resistors in the cards at the ends of the cable See Appendix L 4 4 20 Milliampere Current Loop Mode Appendix I details the correct link settings and connections for current loop operation IC13 and IC14 provide the driver and receiver for this mode The pin out of the current loop mode has been designed to be identical to that used on the IBM PC serial adapter Thus any cable designed to use this interface card should work properly when plugged into the SIO 2 Appendix J and K detail the correct connections for full and half duplex operation in this mode Appendix W details the correct connections for simplex operation in this mode Page 12 01270001 doc Blue Chip Technology Ltd The SIO 2 and Software Page 13 5 0 THE SIO 2 AND SOFTWARE How you drive the SIO 2 depends totally upon the type of application you propose to use it for If the card is set up as COMI and 2 then the channels can be driven from DOS with the exception that half duplex RS485 requires some extra programming in this mode It should be remembered that under MS DOS 3 2 and below there is no software support provided by the operating system for more than the first two serial ports on the system COMI and COM2 Other operating systems such as IBM PC DOS and 386 and PC
23. he port address for channel B is controlled by the mini dip header LKB on the lower left hand side of the board Appendices B and C give example link settings for the normal IBM PC serial ports COMI and COM2 plus the usual ports unofficially allocated by software and hardware manufacturers to COM3 COMS Page 6 01270001 doc Blue Chip Technology Ltd Start up Guide Page 7 The SIO 2 card is normally issued from the factory with channel A set to COMI and channel B set to COM2 It is quite likely that your computer will already have at least one serial port built into it if so then this will usually be occupying the COMI port address There are two solutions to this contention problem 1 Disable the COM1 COM2 on your PC See your PC manual for instructions ii Change the I O port addresses and possibly interrupts on the SIO 2 card See Appendices B C and Q Ensure that no other cards or system devices are set to the same port address or interrupt Multiple SIO 2 cards can use the same interrupts provided that the software is written to support this Extra mini dip green links are provided with your package to enable other address selections to be set 2 4 installing the card If this is the first time that you have installed a peripheral card in your PC you should refer to the instructions in the hardware guide supplied with your machine for information on how to remove the cover and install devices into the I O channel slot
24. ir of devices and can improve the flexibility of the network but is more difficult to implement especially where devices can be switched on or off at any time Current Loop This method of interfacing has been used for a relatively long time now It has a reputation for high integrity in noisy environments and the ability to isolate the various devices within the loop Its weakness is usually transmission rate where 9600 baud is acknowledged as high although 19200 baud is possible and this limits current loop to low speed activities The basis of the current loop interface is that rather than a voltage which is transferred between devices as with RS232 422 and 485 a current is passed instead This figure shows a typical current loop circuit Local Remote ve ses QD 70 V4 K Page 42 01270001 doc Blue Chip Technology Ltd Appendix X Page 43 A constant current generator provides an output from the local device that is fed to the external cabling and passes through an LED light emitting diode at the remote device The current is fed back to the local device and is then switched on or off to provide to modulation of the current to either produce a MARK or SPACE bit Considerations 1 If multiple CL devices are connected in a daisy chain arrangement it may be necessary to fit by pass diodes at each station in case the cable is disconnected Station 1 Station 2 By d
25. kee 15 Blue Chip Technology SIO 2 Rev 15 RR 16 Standard Port Allocations for PC 16 Ports on KA or LKB terere teet 16 APPENDIX Coc titer 17 Blue Chip Technology Ltd 01270001 doc Contents Standard Port Allocations for PC 17 Ponts om LKB stet RR RR RR RR ERU RARE RR 17 APPENDIX tet RAT 18 Channel RS232 18 APPENDIX E i citet 19 025 Pin to D9 Pin Adapter eee 19 APPENDIX em 20 Channel B RS232 422 485 Current 20 e te RR E 21 Channel B R232 Full Duplex Mode 21 dua Bd a 22 Connecting Another DTE Device to the SIO 2 Channel B A Null Modem Cable iiti metere i mni 22 APPENDIX tete 23 Channel B 20mA Current Loop 23 APPENDIX 24 Current Loop Full Duplex Connection to Another SIO 2 24 APPENDIX cte teet testi ete tette 25 SIO 2 Current Loop Half Duplex Point to Point Connection to Another
26. l modem cable concept Appendix H can be used again for this connection and it should be remembered that for cable lengths of over 50 feet another interface such as RS422 485 should be considered 3 4 Connecting a Mouse We recommend the Microsoft Serial Mouse for use with the SIO 2 This comes with an adapter for both D9 and D25 connections There are other mice on the market and provided they are designed to work through a standard IBM PC serial port then they should present no problem If you do experience problems please refer to the supplier of the mouse first before contacting us Blue Chip Technology can supply a complete range of printers mice plotters and external terminals etc For more details contact our Sales Department Page 10 01270001 doc Blue Chip Technology Ltd Channel B Alternative Interfaces Page 11 4 0 CHANNEL B ALTERNATIVE INTERFACES 41 85422 Full Duplex Mode To set the SIO 2 for RS422 full duplex mode refer to Appendix L for the connections and link positions for LKD Appendix A contains a complete drawing of the SIO 2 card detailing the locations of the various links on the board It is important to remember to use good quality shielded twisted pair cable for this interface especially if a high baud rate i e greater than 2400 is being used The line drive and receiver interface device used for this mode if the 75176 and in this mode IC9 transmits data and 1 8 receives it 4 2 RS485 Half Duple
27. oing so the current path is ensure at all times regardless of whether the connection to the station is made or not It should be remembered that the positive voltage applied at the current generator device will limit the number of series diodes either LED or conventional 2 The capacitance of the cable can affect the CL operation significantly The larger the capacitance and length of the cable the lower the maximum possible transmission rate Blue Chip Technology Ltd 01270001 doc Page 43 Page 44 Appendix x 3 Various permutations of pull ups and pull downs can be used especially on BCT SIO 2 to provide the current path Basically conventional current must flow from a positive voltage to a negative voltage This can be achieved in many ways Local Remote ve VES QD VWF V K Page 44 01270001 doc Blue Chip Technology Ltd
28. sk is not copy protected in any way and you are free to make as many backup copies as you like for your own departments use The disk can be copied onto blank floppy diskette of the same type with the MS DOS command DISKCOPY A A ona single drive or DISKCOPY A B ona twin drive machine Blue Chip Technology Ltd 01270001 doc Page 5 Page 6 Start up Guide If you wish to copy the files to a fixed disk normally drive C use the command MD SIO 2 to make a suitable directory on drive C type CD SIO 2 followed by a carriage return put the SIO 2 floppy disk in drive A and type COPY A C followed by a carriage return This will copy all the files from the SIO 2 disk into the correct directory on drive C 2 3 Selecting the Correct Comms Port Addresses before placing the SIO 2 into your computer I O slot it is necessary to establish and set the correct addresses in the PC port map for the card to use The Sio 2 has two channels each of which required a different address to be set Channel A is connected to the 9 way D type connector on the back panel and provides 1 standard PC serial comms port The address for channel A is controlled bu the mini dip header LKA on the upper left hand side of the board Channel B is connected to the 25 way D type connector on the back panel and provides 1 serial port which can work as a normal PC serial comms port in RS232 and current loop modes or as a special comms port on RS422 485 modes T
29. th SIO 2 Cards xd 00000 x 00000 HE 123 4 5 6 NB FIT LINK LKD 5 TO ENABLE 100 OHM TERMINATING LKC OUT1 DTR RESISTOR IN R4 AT EACH END OF CIRCUIT OUT1 FIT TO SELECT DTR SWITCHING SIGNAL Blue Chip Technology Ltd 01270001 doc Page 29 Page 30 Appendix P APPENDIX P RS485 Multidrop Network up to 32 SIO 2 Cards can be Connected D25 Connections Station 1 Station 1 Use Shielded Twisted Pair Cable Link Positions All Both SIO 2 Cards LKD 8 LKC 0 ENBLE R4 AT EACH OUT1 OUT OUT1 DTR ON CHANNEL B 90900 Envor caste e SWITCHES THE RS485 DTR s DTR 128456 CIRCUIT ON AND OFF LKE O FIT TO SELECT FUL SWITCHING SIGNAL HLF ie Page 30 01270001 doc Blue Chip Technology Ltd Appendix Q Page 31 APPENDIX Q Interrupt Link Setting for Channels A and B D25 Connections Station 1 Station 1 Use Shielded Twisted Pair Cable Link Positions All Both SIO 2 Cards LKD 5 5 LKC e 0 ENBLE R4 AT EACH OUT1 OUT OUT1 DTR ON CHANNEL B 99900 EnD oF caste e SWITCHES THE RS485 123 4 5 6 DIR IOJ PIR CIRCUIT ON AND OFF LKE O FIT TO SELECT FUL SWITCHING SIGNAL HLF e Blue Chip Technology Ltd 01270001 doc Page 31 Page 32 Appendix R APPENDIX R PC XT AT Port Map I O Address Map Address 000 01F DMA controller 1 8237A 5 02 03F Interrupt controller 1 8259A 040 05F Timer 8254 060 06F Keyboard controller 8742
30. x Mode N B Remember when using this mode to fit good quality shielded twisted pair cable and also to install the links to enable the 1000hm terminating resistors in the cards at the ends of the cable See Appendix L Communication on a single twisted pair can be achieved with RS485 half duplex mode Appendix N details the link settings and connections for this mode IC9 is used alone to provide this interface and consequently it must be switched from receive to transmit and back again to receive when the user wishes to send a message Blue Chip Technology Ltd 01270001 doc Page 11 Page 12 Channel B Alternative Interfaces The signal to switch the Tx and Rx can be selected as DTR or OUTI from the channel BB 164550 device Link C allows you to select the appropriate signal By setting the selected signal to a high state IC9 is put into the Receive mode RS485 half duplex is very useful mode of operation for data acquisition and message switching between PC based equipment Appendix O details how to connect two SIO 2 cards back to back in this mode 4 3 RS485 Multi Drop Network Mode Appendix P details how to couple up multiple SIO 2 cards to form a multi drop network which is capable of communication at distances of up to 1 kilometre dependent upon baud rate Please remember that the protocol for using this mode of operation is totally dependent upon the user designing software to avoid message collision and provide some form of pack
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