MODEL USB-COM-4SM USER MANUAL
Contents
1. Two Wire m Two Wire Two Wire Two Wire COMC Figure 3 2 Option Selection Map RS485 Mode m RS485 Mode Two Wire Two Wire EH 485 Term m 2 485 Term Special 4 Wire RS485 Modes D 55485 Mod Two Wire m 2 485 Term Two Wire Two Wire COM D 0 22 0 175 0 780 0 175 The board has 4 separate channels which can be individually configured Each channel can be used in one of four modes 1 RS232 Install the top jumper in the RS232 position left 2 RS422 Install the top jumper in the RS422 RS485 position right 3 RS485 4 wire Install the top jumper in the RS422 RS485 position right and the RS485 The jumpers on the card must be properly placed in order to have the card function properly Notes Any unneeded jumpers that are installed can cause the adapter to function incorrectly 10 4 RS485 2 wire mode Install the top jumper in the RS422 RS485 position right the RS485 Mode jumper the RS485 TxRx jumper and the RS485 TxRx jumper To provide a termination load in the RS485 mode install the appropriate RS485 TERM jumper Manual USB COM 4SM Chapter 4 Programming Sample Programs There are sample programs provided with the board in several Windows languages Windows samples are located in the WIN32 directory Windows Programming The board installs into Windows as COM ports Thus the Wind2. 10 Chapter 4 Programming eee i eer ege diee ca epiac eet ee Da enda do na deeds eu eod ed dne S 11 Chapter 5 Connector Pin Assignments nennen nennen nennen 12 Table 5 1 Connector Pin Assignments ennemi nennen nnns 12 Appendix A Application Considerations sss ener 13 Table A 1 Connections Between Two RS422 Devices sssssssseee eene 13 Table A 2 RS422 485 Specification Summary sse enemies 14 RS485 Data Transmission eo oe puri il alum 14 Figure A 1 Typical RS485 Two Wire Multidrop Network ssseee mmn 15 4 Manual USB COM 4SM Chapter 1 Introduction This Serial Adapter was designed for effective multipoint transmission in any one of three modes on each channel These modes are RS232 RS422 and RS485 EIA485 protocol The card features four independent asynchronous serial ports RS422 Balanced Mode Operation The board supports RS422 communications and uses differential balanced drivers for long range and noise immunity The board also has the capability to add load resistors to terminate the communications lines RS422 communications requires that a transmitter supply a bias voltage to ensure a known zero state Also receiver inputs at each end of the network should be terminated to eliminate ringing The board supports biasing by default and supports terminat
3. Network An RS485 network can also be connected in a four wire mode In a four wire network it s necessary that one node be a master node and all others be slaves The network is connected so that the master communicates to all slaves and all slaves communicate only with the master This has advantages in equipment that uses mixed protocol communications Since the slave nodes never listen to another slave s response to the master a slave node cannot reply incorrectly 15 Manual USB COM 4SM 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 ACCES 1 0 PRODUCTS INC 10623 Roselle Street San Diego CA 92121 Tel 858 550 9559 FAX 858 550 7322 www accesio com 16 Manual USB COM 4SM
4. errors are the result of noise induced on the cables The RS422 standard permits cable lengths up to 5000 feet and because it operates in the differential mode it is more immune to induced noise Connections between two RS422 devices with CTS ignored should be as follows Table A 1 Connections Between Two RS422 Devices 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 all 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 In a 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 that connects the driver to its output terminals If the 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 drive
5. should be terminated at the receiving end in its characteristic impedance Installing a jumper at the locations labeled RS485 LD applies a 1200 load across the transmit receive input output for RS485 operation Jumpers having to do with the termination of each channel are located near the output connector They are labeled by channel The load jumper is labeled RS485 LD The other two jumpers used to connect the transmit and receive lines for the two wire RS485 mode Tx Rx RS485 Term 1200 0 01 pF Tx Rx Figure 3 1 Simplified Termination Schematic In RS485 operations where there are multiple terminals only the RS485 ports at each end of the network should have terminating impedance as described above To terminate the COM A port place a jumper at the location labeled Ch A RS485 To terminate the COM B COM C or COM D ports place jumpers at locations labeled Ch B RS485 Ch C RS485 and Ch D RS485 respectively Also for RS485 operation there must be a bias on the TRX and TRX lines If the adapter is not to provide that bias contact the factory technical support Data Cable Wiring Signal Pin Connection Ain out 2 Ain out 3 100 Q to Ground 5 9 Manual USB COM 4SM 0 22 0 175 0 780 0 175 3 94 USB RS 232 RS422 2 Wire RS 485 RS 485 2 Wire Terminated RS485 Mode 2 Two Wire COMA COMB 6 720 w
6. CES which is found to be defective will be repaired or replaced subject to the following considerations Terms and Conditions If a 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 defecti
7. aud rate up to 921 6K bps The driver receiver used SP491 in non RS232 modes 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 conflict the driver receivers feature thermal shutdown The driver receiver used in RS232 mode is the ICL 3243 5 Manual USB COM 4SM Communication Mode The board supports Half Duplex communications with a 2 wire cable connection Half Duplex allows traffic to travel in both directions but only one way at a time RS485 communications commonly use the Half Duplex mode since they share only a single pair of wires Baud Rate Ranges The board has capability for baud rates up to 921 6K bps Specifications Communications Interface e e Connection Serial Ports Character length Parity Stop Interval Serial Data Rates achieved by jum Receiver Input Sensitivity Common Mode Rejection Standard USB connector Four male D sub 9 pin connectors 5 6 7 or 8 bits Even odd or none 1 1 5 or 2 bits Up to 115 2K baud Asynchronous A faster range of rates up to 921 6K is per selection 200 mV differential input 12V to 7V Transmitter Output Drive Capability 60 mA with thermal shutdown Bus Type Environmental e USB 2 0 Full Speed Operating Temperature Ran
8. cteristic impedance of the cable An exception to this is the case where 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 adapter Termination resistors for the RX and RX lines are provided on the card and are placed in the circuit when you install the RS 485 jumpers See the Option Selection section of this 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 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 of the line 14 Manual USB COM 4SM TERMINATION RESISTORS AT BOTH ENDS ONLY IX NAHI IK ENA3L RX FNA I RX ENASLE Figure A 1 Typical RS485 Two Wire Multidrop Network RS485 Four Wire Multidrop
9. e install program If the install program does not click START RUN and type click OK or press E C Follow the on screen prompts to install the software for this board Installing the Adapter The board s adapter can be a USB port of an IBM or compatible computer Before installing the adapter carefully read the OPTION SELECTION section of this manual and configure the adapter according to your requirements In Windows the SETUP EXE program will lead you through the process of setting the options on the board The setup program does not set the options These must be set manually by jumpers on the board within the case of the adapter To Install the Adapter 1 Install jumpers from either the Option Selection section of this manual or the suggestions of the SETUP EXE software program 2 Enter the CMOS setup program of your system and verify that the USB plug and play option is set appropriately for your system Systems running Windows 98 2000 XP or any other PNP compliant Operating System should set the CMOS option to OS 8 Manual USB COM 4SM 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 For the convenience of the user the jumpers are clearly silk screened Terminations A transmission line
10. ge 0 C to 60 C Storage temperature Range Humidity Power Required Size 50 C to 120 C 5 to 95 non condensing Approximately 110 mA plus loads up to an additional 240 mA from USB bus 7 25 inches wide 184 4 mm by 4 35 inches deep 110 5 mm by 1 16 inches high 29 5 mm 6 Manual USB COM 4SM USB BUS 4 X d y USB cr 4 HUB 4 p N M b 2 COMB COMC COM D USB BASED ACTIVITY UART y P y en RS485 RS422 MODE RS232 RS422 R8485 SELECT XCVR is BUFFERS 232 MODE SELECT e e 2 WIRE RS485 lt RS485 es t RS422 LOOPBACK SELECT TERMINATION 4 MALE DB 9 CONNECTOR USB COM 4SM BLOCK DIAGRAM Figure 1 1 Block Diagram Only one serial channel shown Manual USB COM 4SM Chapter 2 Installation Software CD Installation These paragraphs are intended to detail the software installation steps as well as describe what is being installed The software provided with this board is contained on one CD and must be installed onto your hard disk prior to use To do this perform the following steps as appropriate for your operating system Substitute the appropriate drive letter for your drive where you see d in the examples below WIN98 Me 2000 XP 2003 a Place the CD into your CD ROM drive b The CD should automatically run th
11. ion by jumpers on the card If your application requires the transmitter to be un biased please contact the factory RS485 Balanced Mode Operation The board supports RS485 communications and uses differential balanced drivers for long range and noise immunity RS485 operation involves 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 This board 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 transmitters are off Also receiver inputs at each end of the network should be terminated to eliminate ringing The card 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 The FT232BM UARTS are used as Asynchronous Communication Elements ACE These include 128 byte transmit amp 384 byte receive buffers to protect against lost data in multitasking operating systems while maintaining 100 percent compatibility with the original IBM serial port The system assigns the address es A crystal oscillator is located on the board This oscillator permits precise selection of b
12. ows 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 Address Map The core of the UART function is supplied by the FTDI FT232BM chip 11 Manual USB COM 4SM Chapter 5 Connector Pin Assignments Input Output Connections The Serial Communications board uses four individual DB9 connectors Proper EMI cabling techniques include using shielded twisted pair wiring for the input output wiring DB 9 Male Pin for RS 232 Signals RS 485 Signals RS 422 Signals xi RR 6 2 ARX 1X e G O cos CIS SE S SSS R Re Table 5 1 Connector Pin Assignments 1 RS485 2 wire requires the installation of jumpers on the card to properly connect these pins 12 Manual USB COM 4SM Appendix A Application Considerations Introduction Working with RS422 and RS485 devices is not much different from working with standard RS232 serial devices and these two standards overcome deficiencies in the RS232 standard First the cable length between two RS232 devices must be short less than 50 feet at 9600 baud Second many RS232
13. rs 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 If the differential voltage input is less than 200 mV the receiver will provide the opposite logic state on its output A maximum operating voltage range is from 6V to 6V allows 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 13 Manual USB COM 4SM common mode voltage within that range The circuit may operate without the ground connection but may not be reliable eine Driver Output Voltage unloaded Driver Output Voltage loaded RS485 TERM SE Driver Output Resistance a 500 Driver Output Short Circuit Current 10 150 Driver Output Rise Time 10 unit interval Receiver Sensitivity 200 mV Receiver Common Mode Voltage Range 7V Receiver Input Resistance 4KQ Table A 2 RS422 485 Specification Summary 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 equal to the chara
14. ve during the warranty period In no case is ACCES liable for 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 if in 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 3 Manual USB COM 4SM Table of Contents Chapter 1 Introduction nocte pedet ne diee e cie dein git eue e e epi npe TRE tbe 5 RS422 Balanced Mode Operation 2 2 5 RS485 Balanced Mode Operation 5 Specifications a A a rn dea te ee eed ne ete 6 Figure 1 1 Block Diagram Only one serial channel shown sssseeee eem 7 Chapter 2 Installation 22 eee Ao Rae ede ede egere sie pe oca erede ee a ed dards 8 Chapter 3 Option Selection niini e ed eee a el an sah Red de ce e pe eee Dando sagen 9 Figure 3 1 Simplified Termination Schematic sss eene nennen 9 Figure 3 2 Option Selection Map
15. ya ACCES 1 0 PRODUCTS INC 10623 Roselle Street San Diego CA 92121 858 550 9559 Fax 858 550 7322 contactus accesio com www accesio com MODEL USB COM 4SM USER MANUAL FILE MUSB COM 4SM A1g Notice The information in this document is provided for reference only ACCES does not assume any liability arising out of the 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 2005 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 BOARD CONNECTING AND DISCONNECTING CABLES OR INSTALLING BOARDS INTO A SYSTEM WITH THE COMPUTER OR FIELD POWER ON MAY CAUSE DAMAGE TO THE I O BOARD AND WILL VOID ALL WARRANTIES IMPLIED OR EXPRESSED 2 Manual USB COM 4SM 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 AC
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