MODEL COM485/8 USER MANUAL
Contents
1. Typical RS485 Two Wire Multidrop Network List of Tables COM485 8 Address Switches Example Address Setup Standard DOS COM Port Addresses Baud Rate Divisor Values RS422 Specification Summary Py w lu pe E N ku NR lin Ni Chapter 1 Introduction The COM485 8 Serial Interface Card contains eightindependent ports and provides effective RS485 multipoint communication The COM485 8 is 13 38 inches long and may only be installed in long slots of IBM PC XT AT or compatible computers Ifinstalled in an eight bit slot the high interrupts IRQ 10 15 will not be available to the COM485 8 RS485 Balanced Mode Operation The COM485 8 supports RS485 modes that use differential balanced drivers for increased range and noise immunity RS485 improves on RS422 with switchable transceivers and the ability to support multiple devices on a single party line The RS485 specification defines a maximum of 32 devices on a single line The number of devices served on a single line can be expanded by use of repeaters COM485 8 also has the capability to add load resistors to terminate the communications lines RS485 communications requires that one transmitter supply a bias voltage to ensure a known zero state when all transmitte2. 5 gt Port B pin 5 Click on Start gt Programs gt Accessories gt Hyperterminal gt Hyperterm Set to the first com port number for the board Repeat step 18 and select the second com port number Size the window so you can see both windows By typing in either window you should see the characters in the other window The board is now successfully installed Manual MCOM485 8 E1c Chapter 3 Option Selection To help you locate the jumpers described in this section refer to the Option Selection Map at the end of this section Operation of the serial communications section is determined by jumper installation as described in the following paragraphs Terminations A transmission line should be terminated at the receiving end in its characteristic impedance Installing a jumper at the location labeled TERM applies a 1209 load across the transmit receive input output for RS485 operation In RS485 operations where there are multiple terminals only the RS485 ports at each end of the network should have terminating resistors as described Rx above Also for RS485 operation there must be a bias Bug on the RX and RX lines If the COM485 8 card is not to provide that bias contact the factory technical 8 support s Rx Data Cable Wiring Signal Pin Connection Figure 3 1 Simplified Termination Schematic Tx and Rx 2 Tx and Rx 3 Ground 5 Interrupts In addition to standard interrupt levels IRO2 through IRQ7 the COM
3. be making modifications to the Windows NT registry Use extreme caution while doing so A mistake could mean reloading the operating system 13 Select the HKEY LOCAL MACHINE window Double click on System gt Current Control Set gt Services gt Serial in the left hand window 14 In the left window find Parameters and double click on it Select the first Serial Each system will have different numbers for the comports based on currently installed com ports and verify that the DosAddress value is the same as your Port A value If not select the next Serial until you find a match Manual MCOM485 8 E1c Page 2 7 COM485 8 Manual 15 16 17 19 20 Page 2 8 RD Perform the following steps on each Serial for the board Click on Edit Add Value In Value Name type InterruptStatus In Data Type select REG_DWORD Click OK Enter in a value equal to the first port base address plus 400 for all ports In the example of 300 hex being the first port all ofthese entries would be 700 If you are using base address 100 hex the entry would be 500 Click on Edit Add Value In Value Name type PortIndex In Data Type select REG_DWORD Click OK Enter a 1 for the first port 2 for the second port and so on until all eight ports are indexed Close regedt32 and restart Windows NT Loop Port A to Port B with the following pins Port A pin 2 gt Port B pin 2 Port A pin 3 gt Port B pin 3 Port A pin
4. 0 mV Receiver Sensitivity Receiver Common Mode Voltage Range Receiver Input Resistance Table A 1 RS422 Specification Summary 7V Driver Output Rise Time 4KO To prevent signal reflections in the cable and to improve noise rejection in both the RS422 and RS485 mode the receiver end of the cable should be terminated with a resistance egual to the characteristic impedance ofthe cable The exception is when the line is driven by an RS422 driver that is never tristated or disconnected from the line In this case the driver provides a low internal impedance that terminates the line at that end Note You do not have to add a terminator resistor to your cables when you use the COM485 8 card Termination resistors for the RX and RX lines are provided on the card and are placed in the circuit when you install the LOAD LD jumpers See the Option Selection section ofthis manual RS485 Data Transmission The RS485 Standard allows a balanced transmission line to be shared in a party line mode As many as 32 driver receiver pairs can share a two wire party line network Many characteristics of the drivers and receivers are the same as in the RS422 Standard One difference is that the common mode voltage limit is extended and is 12V to 7V Since any driver can be disconnected or tristated from the line it must withstand this common mode voltage range while in the tristate condition Page A 2 Manual MCOM485 8 E1c RS485
5. 485 8 also supports higher interrupts IRQ10 through IRQ15 Except IRQ13 and others reserved by other installed hardware Select the desired level by installing a jumper in one of these locations for each channel If the COM485 8 is installed in a short eight bit slot the higher interrupts IRQ10 through IRQ15 will be unavailable to the card Please note In WindowsNT changes must be made to the System Registry to support IRQ sharing The following is excerpted from Controlling Multiport Serial 1 0 Cards provided by Microsoft in the MSDN library Documentid mk ivt nt40res D15 S55FC HTM also available in the Windows NT Resource Kit The text enclosed in brackets denotes a comment The Microsoft serial driver can be used to control many dumb multiport serial cards Dumb indicates that the control includes no on board processor Each port of a multiport board has a separate subkey under the CurrentControlSet Services Serial Parameters subkey in the Registry In each of these subkeys you must add values for DosDevices Interrupt InterruptStatus Port Address and Portlndex because these are not detected by the Hardware Recognizer For descriptions and ranges for these values see Regentry hlp the Registry help file on the Windows NT Workstation Resource Kit CD Manual MCOM485 8 E1c Page 3 1 COM485 8 Manual For example if you have an eight port COM485 8 board configured to use address 0x100 with an interrupt of 0x5 the values in t
6. 85 8 E1c COMD COMH OUTPUT _ADDRESS ADDRESS goog D H ALETTE PALIT Pi fe FE COMC COMG Gla Ef _ ADDRESS ADDRESS A3 1900485 A9 A3 EEE A9 COMB COMF ADDRESS ADDRESS i XI X4 ji ia mano ts BAS COMA COME _ADDRESS ADDRESS ALETTE CGT SEES gt gt gt 388888 Figure 3 2 COM485 8 Option Selection Map Manual MCOM485 8 E1c Page 3 3 COM485 8 Manual Page 3 4 Manual MCOM485 8 E1c Chapter 4 Address Selection Each COM485 8 port s base address can be selected anywhere within an I O address range of 100 3F8 hex providingthatthe address does not overlap with other functions The FINDBASE base address locator program provided with your card will assist you to select a base address that will avoid this conflict If the addresses of two installed functions overlap you will experience unpredictable computer behavior I O bus address switches are marked A3 A9 The following table lists the switch labels vs the address line controlled and the relative weights of each Address Switch Settings 1st Digit 2nd Digit 3rd Digit Switch Label 7 6 5 4 3 2 1 Address Line Controlled A9 A8 A7 A6 A5 A4 A3 Decimal Weight 512 256 128 6 8 64 32 1 Hexadesima Weight 200 100 so 40 20 10 Table 4 1 COM485 8 Address Switches In order to read the address switch setup assign
7. IRQs 10 15 will be unavailable If your card is CE Marked it meets the requirements of EN50081 1 1992 Emissions EN50082 1 1992 Immunity and EN60950 1992 Safety Manual MCOM485 8 E1c Page 1 3 COM485 8 Manual N ADDRESS lt DECODE OSCILLATOR LOGIC N m lt gt Y A z N 2 UART DATA A on 9 TRANSCEIVER BUFFER SIMILAR je N Er AUTO RTS less CIRCUITRY TRANSCEIVER DIRECTION CONTROL Figure 1 1 COM485 8 Block Diagram Only one serial channel shown Page 1 4 Manual MCOM485 8 E 1c Chapter 2 Installation The software provided with this card is contained on either one CD or multiple diskettes and must be installed onto your hard disk prior touse To do this perform the following steps as appropriate for your software format and operating system Substitute the appropriate drive letter for your CD ROM or disk drive where you see d or a respectively in the examples below CD Installation DOS WIN3 x 1 Place the CD into your CD ROM drive 2 Type LJE to change the active drive to the CD ROM drive 3 Type JASJE to run the install program 4 Follow the on screen prompts to install the software for this card WIN95 98 NT 2000 a Place the CD into your CD ROM drive b The CD should automatically run the install program after 30 seconds Ifthe install program does not run click START RUN and type d insta
8. Iva ACCES I O PRODUCTS INC 10623 Roselle Street San Diego CA 92121 TEL 858 550 9559 FAX 858 550 7322 MODEL COM485 8 USER MANUAL FILE MCOM485 8 E1c Notice The information in this document is provided for reference only ACCES does not assume any liability arising out ofthe application or use of the information or products described herein This document may contain or reference information and products protected by copyrights or patents and does not convey any license under the patent rights of ACCES nor the rights of others IBM PC PC XT and PC AT are registered trademarks of the International Business Machines Corporation Printed in USA Copyright 2001 by ACCES I O Products Inc 10623 Roselle Street San Diego CA 92121 All rights reserved WARNING ALWAYS CONNECT AND DISCONNECT YOUR FIELD CABLING WITH THE COMPUTER POWER OFF ALWAYS TURN COMPUTER POWER OFF BEFORE INSTALLING A CARD CONNECTING AND DISCONNECTING CABLES OR INSTALLING CARDS INTO A SYSTEM WITH THE COMPUTER OR FIELD POWER ON MAY CAUSE DAMAGE TO THE I O CARD AND WILL VOID ALL WARRANTIES IMPLIED OR EXPRESSED Page 111 Warranty Prior to shipment ACCES equipment is thoroughly inspected and tested to applicable specifications However should equipment failure occur ACCES assures its customers that prompt service and support will be available All equipment originally manufactured by ACCES which is found to be defective will be repaired or replaced s
9. Length 4000 ft 4000 ft These are theoretical maximums based on typical conditions and good quality cables Table 5 1 Baud Rate Divisor Values In C the code to set the chip to 9600 baud is outportb BASEADDR 0x0C outportb BASEADDR 1 0 The second initializing step is to set the Line Control Register at Base Address 3 This register defines word length stop bits parity and the DLAB Bits 0 and 1 control word length and allow word lengths from 5 to 8 bits Bit settings are extracted by subtracting 5 from the desired word length Bit 2 determines the number of stop bits There can be either one or two stop bits If Bit 2 is set to 0 there will be one stop bit If Bit 2 is set to 1 there will be two stop bits Bits 3 through 6 control parity and break enable They are not commonly used for communications and should be set to zeroes Page 5 2 Manual MCOM485 8 E1c Bit 7 is the DLAB discussed earlier It must be set to zero after the divisor is loaded or else there will be no communications The C command to set the UART for an 8 bit word no parity and one stop bit is outportb BASEADDR 3 0x03 The final initialization step is to flush the receiver buffers You do this with two reads from the receiver buffer at Base Address 0 When done the UART is ready to use Reception Reception can be handled in two ways polling and interrupt driven When polling reception is accomplished by constantly reading the Line
10. Status Register at Base Address 5 Bit 0 of this register is set high whenever data are ready to be read from the chip A simple polling loop must continuously check this bit and read in data as it becomes available The following code fragment implements a polling loop and uses a value of 13 ASCII Carriage Return as an end of transmission marker do t while inportb BASEADDR 5 amp 1 Wait until data ready data i inportb BASEADDR while data i 13 Reads the line until null character rec d Interrupt driven communications should be used whenever possible and is required for high data rates Writing an interrupt driven receiver is not much more complex than writing a polled receiver but care should be taken when installing or removing your interrupt handler to avoid writing the wrong interrupt disabling the wrong interrupt or turning interrupts off for too long a period The handler would first read the Interrupt Identification Register at Base Address 2 Ifthe interrupt is for Received Data Available the handler then reads the data If no interrupt is pending control exits the routine A sample handler written in C is as follows readback inportb BASEADDR 2 if readback amp 4 Readback will be set to 4 if data are available data i inportb BASEADDR outportb 0x20 0x20 Write EOI to 8259 Interrupt Controller return Manual MCOM485 8 E1c Page 5 3 COM485 8 Manual Transmission RS485 t
11. Two Wire Multidrop Network The following illustration shows a typical multidrop or party line network Note that the transmission line is terminated on both ends of the line but not at drop points in the middle ofthe line TERMINATION RESISTORS AT BOTH ENDS ONLY TX ENABLE TX ENABLE RX ENABLE RX ENABLE TX ENABLE RX ENABLE Figure A 1 Typical RS485 Two Wire Multidrop Network Manual MCOM485 8 E1c Page A 3 COM485 8 Manual Page A 4 Manual MCOM485 8 E1c COM485 8 Manual Page A 6 Manual MCOM485 8 E1c Customer Comments If you experience any problems with this manual or just want to give us some feedback please email us at manuals accesio com Please detail any errors you find and include your mailing address so that we can send you any manual updates Ma ACCES 1 0 PRODUCTS INC 10623 Roselle Street San Diego CA 92121 Tel 858 550 9559 FAX 858 550 7322 www accesio com COM485 8 Manual Page A 8 Manual MCOM485 8 E1c
12. a binary 1 to switches that are turned OFF and a binary 0 to switches in the ON position For example as illustrated in the following table switch selection corresponds to binary 10 1101 1xxx hex 2D8 The xxx represents address lines A2 Al and AO used on the card to select individual registers See Chapter 5 Programming of this manual Switch Label Binary Represent n Conversion Factors HEX Represent n Table 4 2 Example Address Setup Manual MCOM485 8 E1c Page 4 1 COM485 8 Manual The following table lists standard DOS COM Port addresses COM Port IRQ Address A9 AS AT A6 A5 A4 AZ COMI IRQ 4 3F8 1 1 1 1 1 1 1 COM2 IRQ 3 1 0 1 1 1 1 1 COM3 IRQ4 E Zz YE er Ser A A Table 4 3 Standard DOS COM Port Addresses Notice that only two interrupts are assigned to four serial ports Sharing interrupts is not a good idea if both ports are used at the same time unless using an operating system designed for it like Windows NT IRQ Status Registers The COM485 8 uses the industry standard 16550 UART and includes the ability to share up to eight interrupts on one IRQ line This requires the addition of an IRQ Status Register This register 1s located at COMA base address 0x400 So if COMA is set to 0x350 this status register is located at 0x750 Page 4 2 Manual MCOM485 8 E1c Chapter 5 Programming Sample Programs There are sample programs provided with the COM485 8 card in C Pasca
13. anguage Subdirectories containing samples for Win95 98 and NT WinRISC exe A Windows dumb terminal type communication program designed for RS422 485 operation Used primarily with Remote Data Acquisition Pods and our RS422 485 serial communication product line Can be used to say hello to an installed modem ACCES32 This directory contains the Windows 95 98 NT driver used to provide access to the hardware registers when writing 32 bit Windows software Several samples are provided in a variety of languages to demonstrate how to use this driver The DLL provides four functions InPortB OutPortB InPort and OutPort to access the hardware This directory also contains the device driver for Windows NT ACCESNT SYS This device driver provides register level hardware access in Windows NT Two methods of using the driver are available through ACCES32 DLL recommended and through the DevicelOControl handles provided by ACCESNT SYS slightly faster Page 2 2 Manual MCOM485 8 E 1c SAMPLES Samples for using ACCES32 DLL are provided in this directory Using this DLL not only makes the hardware programming easier MUCH easier but also one source file can be used for both Windows 95 98 and WindowsNT One executable can run under both operating systems and still have full access to the hardware registers The DLL is used exactly like any other DLL so it is compatible with any language capable of using 32 bit DLLs Consult the manuals provided with
14. at connects the driver to its output terminals Ifthe enable signal is OFF the driver is disconnected from the transmission line This disconnected or disabled condition is usually referred to as the tristate condition and represents a high impedance RS485 drivers must have this control capability RS422 drivers may have this control but it is not always required A balanced differential line receiver senses the voltage state of the transmission line across the two signal input lines If the differential input voltage is greater than 200 mV the receiver will provide a specific logic state on its output Ifthe differential voltage input is less than 200 mV the receiver will provide the opposite logic state on its output The maximum operating voltage range is from 6V to 6V allowing for voltage attenuation that can occur on long transmission cables A maximum common mode voltage rating of 7V provides good noise immunity from voltages induced on the twisted pair lines The signal ground line connection is necessary in order to keep the common mode voltage within that range The circuit may operate without the ground connection but may not be reliable Manual MCOM485 8 E1c Page A 1 COM485 8 Manual Driver Output Voltage unloaded Driver Output Voltage loaded Driver Output Resistance s lt lt 5 AR lt a lt le O 50 Driver Output Short Circuit Current 150 mA 10 unit interval E20
15. ces overlap you will experience unpredictable computer behavior Page 2 4 Manual MCOM485 8 E1c To Install the Card 1 Turn off the computer power 2 Remove the computer cover 3 Remove the blank VO backplate 4 Install jumpers for selected options from either the OPTION SELECTION section of this manual or the suggestions of our setup software program Select the base address on the card using either the ADDRESS SELECTION section of this manual or the suggestions for COM485 8 in our FINDBASE setup software program Install the card in an I O expansion slot Install the VO cable Inspect for proper fit of the card and cable and tighten screws Replace the computer cover a OOO 1 Note Ifinstalled in an eight bit slot IROs 10 15 will be unavailable A spider cable is provided to interface between the 25 pin connector on the card and your system cabling Eight individual 9 pin connectors are provided To ensure that there is minimum susceptibility to EMI and minimum radiation it is important that the card mounting bracket be properly screwed into place and that there be a positive chassis ground Also proper EMI cabling technigues cable connect to chassis ground at the aperture shielded twisted pair wiring etc must be used for the input output wiring Windows 95 98 Installation Installation in Windows 95 98 is as above with the added step of informing Windows of the existence ofthese ports To do so use the Con
16. cquisition Pods and our RS422 485 serial communication product line Can be used to say hello to an installed modem RISCTerm stands for Really Incredibly Simple Communications TERMinal Setup exe This program is supplied with the COM485 8 as a tool for you to use in configuring jumpers and switches on the card It is menu driven and provides pictures ofthe card on the computer monitor You make simple keystrokes or mouse selections to select functions The picture on the monitor then changes to show how the jumpers or switches should be placed to effect your choices The setup program is a stand alone program that can be run at any time It does not require that the card be plugged into the computer The program is self explanatory with operation instructions and on line help Installing the Card The COM485 8 card can only be installed in a long slot of an IBM PC XT AT or compatible computer Before installing the card carefully read the chapters on Option Selection and Address Selection of this manual and configure the card according to your requirements You can find an open base address with the FINDBASE program on the CD provided with the card Finally our setup program will lead you through the process of setting the options on the COM485 8 The setup program does not set the options on the card These must be set by jumpers on the card Be especially careful with address selection Ifthe addresses of two installed functions cards or devi
17. ct the driver receivers feature thermal shutdown Manual MCOM485 8 E1c Page 1 1 COM485 8 Manual Communication Modes COM485 8 supports Half Duplex communications with a 2 wire cable connection Half Duplex allows traffic to travel in both directions but only one way at atime RS485 communications commonly use the Half Duplex mode since they share only a single pair of wires Auto RTS Transceiver Control In RS485 communications the driver must be enabled and disabled as needed allowing all cards to share a two wire cable The COM485 8 card controls the driver automatically With automatic control the driver is enabled when data is ready to be transmitted The driver remains enabled for the transmission time of one additional character after data transfer is complete and then is disabled The receiver 1s disabled during RS485 transmissions and then enabled when the transmitter driver is disabled The COM485 8 automatically adjusts its timing to the baud rate of the data Note Thanks to this automatic control feature the COM485 8 is ideal for use in Win95 98 applications Shared IRQ Support The COM485 8 card supports sharing of IRQ resources and includes an on board IRQ status register for use with operating systems that support this feature such as Microsoft s WindowsNT This requires one IRQ line to control all eight ports greatly simplifying system configuration Ifone IRQ is used for all 8 channels jumpers must still be install
18. ed for each channel Page 1 2 Manual MCOM485 8 E1c Specifications Communications Interface TO Connection e Serial Ports e Character length e Parity Stop Interval e Serial Data Rates e Address Interrupts e Multipoint 1 25 pin male D sub connector on board mating cable provides eight 9 pin male D sub connectors Eight compatible with RS485 specifications 5 6 7 or 8 bits Even odd or none 1 1 5 or 2 bits 300 to 460 800 Asynchronous Type 16550 buffered UART Each port continuously mappable within 000 to 3FF hex range of AT I O bus addresses Jumper selectable at each port for IRQ 2 7 10 12 14 and 15 Compatible with RS485 specifications Up to 32 drivers and receivers allowed on line Serial communications ACE used is type NS16550 Driver Receivers used are type SN75176EP e Receiver Input Sensitivity 200 mV differential input e Common Mode Rejection 12V to 7V Transmitter Output Drive Capability 60 mA with thermal shutdown Can drive Environmental 32 node 2 wire twisted pair cable up to 4000 feet long e Operating Temperature Range 0 C to 60 C Storage Temperature Range 50 C to 120 C e Humidity e Power Required e Size CE Mark 5 to 95 non condensing 5 VDC at 400 mA typical 800 mA maximum 13 375 long 340 mm by 3 9 high 99 mm If the card is installed in an 8 bit XT style slot the card will work but higher order
19. he Registry are assuming every port is configured to use the same IRQ and the addresses are configured to be consecutive and contiguous Serial Subkey PortAddress REG DWORD 0x100 Interrupt REG_DWORD 5 DosDevices REG_SZ COM3 InterruptStatus REG_DWORD 0x500 PortIndex REG DWORD 1 Serial Subkey PortAddress REG DWORD 0x108 Interrupt REG DWORD 5 DosDevices REG SZ COM4 InterruptStatus REG DWORD 0x500 PortIndex REG DWORD 2 Serial Subkey PortAddress REG DWORD 0x110 Interrupt REG DWORD 5 DosDevices REG SZ COMS5 InterruptStatus REG DWORD 0x500 Portlndex REG DWORD 3 Serial Subkey PortAddress REG DWORD 0x118 Interrupt REG DWORD 5 DosDevices REG SZ COM6 InterruptStatus REG DWORD 0x500 PortIndex REG DWORD 4 Page 3 2 Serial Subkey PortAddress REG DWORD 0x120 Interrupt REG DWORD 5 DosDevices REG SZ COM7 InterruptStatus REG DWORD 0x500 Portlndex REG DWORD 5 Serial Subkey PortAddress REG DWORD 0x128 Interrupt REG DWORD 5 DosDevices REG SZ COM8 InterruptStatus REG DWORD 0x500 Portlndex REG DWORD 6 Serial Subkey PortAddress REG DWORD 0x130 Interrupt REG DWORD 5 DosDevices REG SZ COM9 InterruptStatus REG DWORD 0x500 Portlndex REG DWORD 7 Serial Subkey PortAddress REG DWORD 0x138 Interrupt REG DWORD 5 DosDevices REG SZ COM10 InterruptStatus REG DWORD 0x500 PortIndex REG DWORD 8 Manual MCOM4
20. l QuickBASIC and several Windows languages DOS samples are located in the DOS directory and Windows samples are located in the WIN32 directory Windows Programming The COM485 8 card installs into Windows as COM ports Thus the Windows standard API functions can be used In particular gt CreateFile and CloseHandle for opening and closing a port gt SetupComm SetCommTimeouts GetCommState and SetCommState to set and change a port s settings gt ReadFile and WriteFile for accessing a port See the documentation for your chosen language for details Under DOS the process is very different The remainder of this chapter describes DOS programming Initialization Initializing the chip requires knowledge of the UART s register set The first step is to set the baud rate divisor You do this by first setting the DLAB Divisor Latch Access Bit high This bitis Bit 7 at Base Address 3 In C code the call would be outportt BASEADDR 3 0x80 You then load the divisor into Base Address 0 low byte and Base Address 1 high byte The following equation defines the relationship between baud rate and divisor desired baud rate crystal frequency 32 divisor Manual MCOM485 8 E1c Page 5 1 COM485 8 Manual On the COM485 8 card the UART clock frequency is selectable to 1 8432 MHz X1 or 7 3728 MHz X4 Below is a table for the popular divisor frequencies Divisor Divisor Max Diff xl Cable
21. ll click OK or press Ex C Follow the on screen prompts to install the software for this card 3 5 Inch Diskette Installation As with any software package you should make backup copies for everyday use and store your original master diskettes in a safe location The easiest way to make a backup copy is to use the DOS DISKCOPY utility In a single drive system the command is gasa A JJ You willneed to swap disks as requested by the system In a two disk system the command is Se A el Jen This will copy the contents of the master disk in drive A to the backup disk in drive B Manual MCOM485 8 E1c Page 2 1 COM485 8 Manual To copy the files on the master diskette to your hard disk perform the following steps 1 Place the master diskette into a floppy drive 2 Change the active drive to the drive that has the diskette installed For example if the diskette is in drive A type LJE 3 Type WJnjisjT jaji ji Jened and follow the on screen prompts Directories Created on the Hard Disk The installation process will create several directories on your hard disk If you accept the installation defaults the following structure will exist CARDNAME Root or base directory containing the SETUP EXE setup program used to help you configure jumpers and calibrate the card DOSIPSAMPLES A subdirectory of CARDNAME that contains Pascal samples DOS CSAMPLES A subdirectory of CARDNAME that contains C samples Win32 l
22. lling the Card 2 4 Windows 95 98 Installation 2 5 Windows NT 4 0 Installation 2 5 Chapter 3 Option Selection 3 1 Chapter 4 Address Selection 4 1 IRQ Status Registers 4 2 Chapter 5 Programming 000 c cece eee eee nunnana nan na 5 1 Sample Progfams 5 1 Windows Programming 5 1 Initialization oi a er Bee BY een 5 1 Reception 1444424 re Maa E E a WA a ee 5 3 Transmission assena a AREE eee 5 4 Chapter 6 Connector Pin Assignments 6 1 Appendix A Application Considerations A 1 IHtrodUEtION serea a ii ze A 1 Balanced Differential Signals A 1 RS485 Data Transmission A 2 Page v Figure 1 1 Figure 3 1 Figure 3 2 Figure A 1 Table 4 1 Table 4 2 Table 4 3 Table 5 1 Table 6 1 Connector Pin Assignments Table A 1 Page vi List of Figures COM485 8 Block Diagram Simplified Termination Schematic COM485 8 Option SelectionMap
23. m a DOS prompt type DEBUG and press Enter You will receive a on the left hand side of the screen What we are going to do is read the control port for each new COM port added If you do not receive a 60 back after you read it then you need to re verify the address switch settings Atthe type i base 5 substituting the address for the first port plus 5 For base address 300 the read would be i 305 and the next port would be i 30d Fill in the following table with your addresses and the response you got in return Example Address Result 305 30D 315 31D 325 32D 335 33D AAA ER Once you have received a 60 response from reading all of the control registers remove the floppy and reboot the machine going into Windows NT In Windows NT click on Start gt Settings gt Control Panel gt Ports Manual MCOM485 8 E1c 10 Set up the ports following these steps Click Add Make note of the Com Port Number in the table below Set the base address to the first port address on your card Set the Interrupt Request Line IRQ to the IRQ you selected Click OK Click on Don t Restart Now Repeat these steps for the remaining seven ports writing down the com port number in the table below ae N gt COM 485 8 CE Port COM Port Number 11 Once all the ports have been added close the Ports Applet and the Control Panel without restarting 12 Click Start gt Run and type regedt32 and click OK Caution You will
24. or consequential or special damage arriving from use or misuse of our product The customer is responsible for all charges caused by modifications or additions to ACCES equipment not approved in writing by ACCES or ifin ACCES opinion the equipment has been subjected to abnormal use Abnormal use for purposes of this warranty is defined as any use to which the equipment is exposed other than that use specified or intended as evidenced by purchase or sales representation Other than the above no other warranty expressed or implied shall apply to any and all such equipment furnished or sold by ACCES Page iv Table of Contents Chapter 1 Introduction 1 1 RS485 Balanced Mode Operation 1 1 COM Port Compatibility 1 1 Communication Modes 1 2 Auto RTS Transceiver Control 0 0 0 0c eee ee eens 1 2 Shared IRA Support aae sacie aiis a ie AA eee 1 2 OPEGITIGALLONS u ic A a A a ae Ra al de a la wv ae 1 3 CE Mark se a ae A O M es ee See 1 3 Chapter 2 Installation 2 1 CD Installation aa ai eee eee eee eens 2 1 3 5 Inch Diskette Installation 2 1 Directories Created on the Hard Disk 2 2 Insta
25. ransmission is simple to implement The AUTO feature of the COM485 8 card automatically enables the transmitter when data are ready to send so no software enabling is required To transmit a string of data the transmitter must first check Bit 5 ofthe Line Status Register at Base Address 5 That bit is the transmitter holding register empty flag Ifit is high the transmitter has sent the data The process of checking the bit until it goes high followed by a write is repeated until no data remains The following C code fragment demonstrates this process outportt BASEADDR 4 inportb BASEADDR 4 0x02 Set RTS bit without altering states of other bits while data 1 While there is data to send while inportb BASEADDR 5 amp 0x20 Wait until transmitter is empty outportb BASEADDR data i i gt outportt BASEADDR 4 inportb BASEADDR 4 amp 0xFD Reset RTS bit without altering states of other bits Page 5 4 Manual MCOM485 8 E 1c Chapter 6 Connector Pin Assignments The popular 9 pin D subminiature connector is used for interfacing to communication lines The connector is equipped with 4 40 threaded standoffs female screw lock to provide strain relief RS485 Functions Table 6 1 Connector Pin Assignments Note If connections are to be made to aCOM485 8 S04 CE marked version then CE certifiable cabling and breakout methodology Cable shields connected to ground at the mounting bracket
26. rs are off Also receiver inputs at each end of the network should be terminated to eliminate ringing The COM485 8 supports biasing by default and supports termination by jumpers on the card If your application requires the transmitter to be un biased please contact the factory COM Port Compatibility Type 16550 UARTs are used as the Asynchronous Communication Element ACE These include a 16 byte transmit receive buffer to protect against lost data in multitasking operating systems while maintaining 100 percent compatibility with the original IBM serial port However ports on the COM485 8 card are not restricted to the standard comport addresses Continuous address selection is available anywhere within the I O address range 100 to 3F8 hex Our FINDBASE program will scan I O Bus memory mapped addresses in your computer for available addresses that can be used by the COM485 8 without conflicting with other computer resources A crystal oscillator is located on the card There are x1 and x4 clock rates available This oscillator permits precise selection of baud rate from 300 to 115 200 with the x1 setting and 1200 to 460 800 with the x4 setting The driver receiver used type 75176B is capable of driving extremely long communication lines at high baud rates It can drive up to 60 mA on balanced lines and receive inputs as low as 200 mV differential signal superimposed on common mode noise of 12 V or 7 V In case of communication confli
27. s Specifically it will configure compatible COM cards for IRQ sharing and multiple port issues WIN32IRQ This directory provides a generic interface for IRQ handling in Windows 95 98 NT Source code is provided for the driver greatly simplifying the creation of custom drivers for specific needs Samples are provided to demonstrate the use of the generic driver Note that the use of IRQs in near real time data acquisition programs requires multi threaded application programming techniques and must be considered an intermediate to advanced programming topic Delphi C Builder and Visual C samples are provided Manual MCOM485 8 E1c Page 2 3 COM485 8 Manual Findbase exe DOS utility to determine an available base address for ISA bus non Plug n Play cards Run this program once before the hardware is installed in the computer to determine an available address to give the card Once the address has been determined run the setup program provided with the hardware to see instructions on setting the address switch and various option selections Poly exe A generic utility to convert a table of data into an nth order polynomial Useful for calculating linearization polynomial coefficients for thermocouples and other non linear sensors Risc bat A batch file demonstrating the command line parameters of RISCTerm exe RISCTerm exe A dumb terminal type communication program designed for RS422 485 operation Used primarily with Remote Data A
28. shielded twisted pair wiring etc must be used Manual MCOM485 8 E1c Page 6 1 COM485 8 Manual Page 6 2 Manual MCOM485 8 E1c Appendix A Application Considerations Introduction Working withRS485 devices is notmuch different from working with standard RS232 serial devices and this standard overcomes deficiencies in the RS232 standard First the cable length between two RS232 devices must be short less than 50 feet Second many RS232 errors are the result of noise induced on the cables The RS485 standard permits cable lengths up to 4000 feet and because it operates in differential mode it is more immune to induced noise A third deficiency of RS232 is that more than two devices cannot share the same cable This is also true for RS422 but RS485 offers all the benefits of RS422 plus allows up to 32 devices to share the same twisted pairs An exception to the foregoing is that multiple RS422 devices can share a single cable if only one will talk and the others will always receive Balanced Differential Signals The reason that RS422 and RS485 devices can drive longer lines with more noise immunity than RS232 devices is that a balanced differential drive method is used Ina balanced differential system the voltage produced by the driver appears across a pair of wires A balanced line driver will produce a differential voltage from 2 to 6 volts across its output terminals A balanced line driver can also have an input enable signal th
29. trol Panel Add New Hardware applet Choose to manually install the device froma list select Port and Standard Port Type or similar it varies depending on the version of the OS Then choose a standard communications card When Windows states the address and IRO it has chosen and asks if you want to restart say no Repeat this step for each of the ports Once all eight ports are installed go to the System applet Device Manager select these new ports from the Ports category one at a time and go to Properties Resources Select Manually Configure and change the standard configuration to the last one in the list if any Then change the address and IRQ to the ones selected earlier by Findbase etc Windows NT 4 0 Installation To install the board under Windows NT sharing IRO 1 Set the base address according to the manual This example uses base address 300 hex The Manual MCOM485 8 E1c Page 2 5 COM485 8 Manual Page 2 6 addresses set consecutively will look like COM485 Port Address ve OO oO oo 318 w WB WwW DIN IN o Io O tt 338 Select the IRO With power off install into an ISA slot on the computer Replace screw for hold down bracket With a DOS boot diskette that has DEBUG EXE in the floppy drive turn the computer on Go into BIOS setup verify under PCI PNP Setup that the IRQ you selected is set to ISA LEGACY and not PCI PNP Save settings and exit Fro
30. ubject to the following considerations Terms and Conditions Ifa unit is suspected of failure contact ACCES Customer Service department Be prepared to give the unit model number serial number and a description of the failure symptom s We may suggest some simple tests to confirm the failure We will assign a Return Material Authorization RMA number which must appear on the outer label of the return package All units components should be properly packed for handling and returned with freight prepaid to the ACCES designated Service Center and will be returned to the customer s user s site freight prepaid and invoiced Coverage First Three Years Returned unit part will be repaired and or replaced at ACCES option with no charge for labor or parts not excluded by warranty Warranty commences with equipment shipment Following Years Throughout your equipment s lifetime ACCES stands ready to provide on site or in plant service at reasonable rates similar to those of other manufacturers in the industry Equipment Not Manufactured by ACCES Equipment provided but not manufactured by ACCES is warranted and will be repaired according to the terms and conditions of the respective equipment manufacturer s warranty General Under this Warranty liability of ACCES is limited to replacing repairing or issuing credit at ACCES discretion for any products which are proved to be defective during the warranty period In no case is ACCES liable f
31. your language s compiler for information on using DLLs in your specific environment VBACCES This directory contains sixteen bit DLL drivers for use with VisualBASIC 3 0 and Windows 3 1 only These drivers provide four functions similar to the ACCES32 DLL However this DLL is only compatible with 16 bit executables Migration from 16 bit to 32 bit is simplified because of the similarity between VBACCES and ACCES32 PCI This directory contains PCI bus specific programs and information If you are not using a PCI card this directory will not be installed SOURCE A utility program is provided with source code you can use to determine allocated resources at run time from your own programs in DOS PCIFind exe A utility for DOS and Windows to determine what base addresses and IRQs are allocated to installed PCI cards This program runs two versions depending on the operating system Windows 95 98 NT displays a GUI interface and modifies the registry When run from DOS or Windows3 x a text interface is used For information about the format of the registry key consult the card specific samples provided with the hardware In Windows NT NTioPCLSY S runs each time the computer is booted thereby refreshing the registry as PCI hardware is added or removed In Windows 95 98 NT PCIFind EXE places itselfin the boot sequence ofthe OS torefresh the registry on each power up This program also provides some COM configuration when used with PCI COM port
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