Omega OMG-USB-SER-4 Computer Hardware User Manual
Contents
1. Pumps 4 Industrial pH amp Conductivity Equipment DATA ACQUISITION A Data Acquisition amp Engineering Software 4 Communications Based Acquisition Systems 4 Plug in Cards for Apple IBM amp Compatibles 4 Datalogging Systems A Recorders Printers amp Plotters HEATERS 4 Heating Cable l Cartridge amp Strip Heaters 4 Immersion amp Band Heaters WF Flexible Heaters 4 Laboratory Heaters ENVIRONMENTAL MONITORING AND CONTROL 4 Metering amp Control Instrumentation 4 Refractometers 4 Pumps amp Tubing A Air Soil amp Water Monitors A Industrial Water amp Wastewater Treatment A pH Conductivity amp Dissolved Oxygen Instruments M3900 03032. sales omega fr Daimlerstrasse 26 D 75392 Deckenpfronn Germany TEL 49 0 7056 9398 0 FAX 49 0 7056 9398 29 Toll Free in Germany 0800 639 7678 e mail info omega de One Omega Drive River Bend Technology Centre Northbank Irlam Manchester M44 5BD United Kingdom TEL 44 0 161 777 6611 FAX 44 0 161 777 6622 Toll Free in United Kingdom 0800 488 488 e mail sales omega co uk It is the policy of OMEGA to comply with all worldwide safety and EMC EMI regulations that apply OMEGA is constantly pursuing certification of its products to the European New Approach Directives OMEGA will add the CE mark to every appropriate device upon certification The information contained in this document is believed to be correct but OMEGA Engineering Inc accepts no liability for any errors it contains and reserves the right to alter specifications without notice WARNING These products are not designed for use in and should not be used for patient connected applications Contents COVER VLE Woes si epoca tao pascal cadet ccna 1 WHAT S INCLUDED ccsssssssssssesssssecessecesscesnsnnsseseececeeeecensnssnsnetsieeeeeeeeee 1 OPERATING SYSTEM INSTALLATION sssssssssccesssssesesseesessnneeceeetens 2 SYSTEM INSTAL UATIONS ep Sense 2 ORIGINAL CONFIGURATION cccssssessssesecseeseseceeeeeseseeseeaeseeseeeseeseneeeees ELECTRICAL INTERFACE SELECTION SWITCH EXAMPLES aeara o a PER SWITCH EXAMPLES CONTINUED ccsessesesses
3. The communication parameters are baud rate parity number of data bits per character and stop bits i e 9600 N 8 1 OMG USB SER 4 Page 14 Appendix E Compliance Notices Appendix E Compliance Notices Federal Communications Commission Statement This equipment has been tested and found to comply with the limits for Class B digital device pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures e Reorient or relocate the receiving antenna e Increase the separation between the equipment and receiver e Connect the equipment into an outlet on a circuit different from that to which the receiver is connected e Consult the dealer or an experienced radio TV technician for help Caution Omega Engineering is not responsible for any radio or television interference caused
4. drivers were installed during the SeaCOM software setup procedure Once the drivers are found a new window will pop up indicating the installation of each of the four new ports If you view the system s Device Manager you should have new COM ports in the Ports COM amp LPT Device Class This is shown on the following page OMG USB SER 4 Page 2 Installation System Properties g CDROM EI Disk drives m Display adapters 5 Floppy disk controllers Hard disk controllers Keyboard Monitors Mouse i Network adapters 3 3 Ports COM amp LPT F Communications Port COM1 7 ECP Printer Port LPT1 wo SeaPORT 4 USB Serial Converter Port 1 COM3 wo SeaPORT 4 USB Serial Converter Port 2 COM4 a SeaPORT 4 USB Serial Converter Port 3 COM5 wo SeaPORT 4 USB Serial Converter Port 4 COMB You can access your new COM ports by using the assigned COM identifiers as shown above In this case it is COM3 4 5 and 6 However this assignment will vary from system to system At this point the hardware is recognized and ready to use OMG USB SER 4 Page 3 Configuration Configuration Original configuration This device ships with the following configuration 422 mode 120 ohm termination 1K ohm pull up on RX 1K ohm pull down on RX In order to change this configuration the box must be opened Do this by removing the four screws located on the bottom When reassembling please note th
5. two wire setup the receiver will not echo back transmitted data Note Switch positions 1 and 2 are for port I and switch positions 3 and 4 for port 2 on SW3 Switch positions 1 and 2 are for port 3 and switch positions 3 and 4 for port 4 on SW1 OMG USB SER 4 Page 6 RS 232 RS 422 485 Configuration Switch Examples Continued Port 4 Port 1 Port 2 Port 3 Port 4 Port 3 Port 2 Port 1 SW2 RS 422 485 RS 232 RS 232 RS 422 485 SW4 RS 422 485 RS 232 Port 3 EFN Port 1 L L L TH L T ear T PU po PU PD Port 2 GEU pp L QA pi L Sap T Ga M PU bg W PD EL 1 E3 E4 E5 E6 E7 E8 Figure 3 Electrical Interface Configuration RS 232 The corresponding shunt is in the 232 position The switches will have no effect RS 485 two wire communication with no echo The corresponding shunt is in the 422 485 position Switches 485 2 NE 2 and Port 2 L L T PU and PD are all in the ON position RS 422 with 120 ohmtermination The corresponding shunt is in the 422 485 position Switches 485 3 NE 3 and Port 2 L L PU and PD are all in the OFF position T is in the ON position RS 485 two wire communication with echo The corresponding shunt is in the 422 485 position Switches 485 4 and Port 2 L L T PU and PD are all in the ON position NE 4 is in the OFF position OMG USB SER 4 Page 7 Technical Technical Description The OMG USB SER 4 utilizes four USB UARTs These chips feature
6. MG USB SER 4 is ready for use in your application Please note that if the adapter is configured for 2 wire RS 485 with no echo a loopback test is not possible The receiver in this case will be turned off and the test will fail If you plan on using this device in two wire mode test the adapter in RS 422 mode first Then configure the adapter for your application OMG USB SER 4 Page 10 Appendix B How To Get Assistance Appendix B How To Get Assistance Please refer to Appendix A Troubleshooting prior to calling Technical Support 1 Read this manual thoroughly before attempting to install the adapter in your system 2 When calling for technical assistance please have your user manual and current adapter settings If possible please have the adapter connected in a computer ready to run diagnostics 3 Omega Engineering maintains a home page on the Internet Our home page address is www omega com The latest software updates and newest manuals are available via our FTP site that can be accessed from our home page 4 Technical support is available Monday thru Friday from 8 30 a m to 6 00 p m Eastern time Technical support can be reached at 1 800 DAS IEEE RETURN AUTHORIZATION MUST BE OBTAINED FROM OMEGA BEFORE RETURNED MERCHANDISE WILL BE ACCEPTED AUTHORIZATION CAN BE OBTAINED BY CALLING OMEGA CUSTOMER SERVICE AND REQUESTING AN AUTHORIZED RETURN AR NUMBER OMG USB SER 4 Page 11 Appendix C Electrical I
7. User s Guide www omega com e mail info omega com OMG USB SER 4 Four Port RS 232 422 485 to USB Adaptor OMEGAnet Online Service Internet e mail www omega com info omega com USA ISO 9001 Certified Canada Servicing North America One Omega Drive P O Box 4047 Stamford CT 06907 0047 TEL 203 359 1660 FAX 203 359 7700 e mail info omega com 976 Bergar Laval Quebec H7L 5A1 Canada TEL 514 856 6928 FAX 514 856 6886 e mail info omega ca For immediate technical or application assistance USA and Canada Mexico Benelux Czech Republic France Germany Austria United Kingdom ISO 9002 Certified Sales Service 1 800 826 6342 1 800 TC OMEGA Customer Service 1 800 622 2378 1 800 622 BEST Engineering Service 1 800 872 9436 1 800 USA WHEN TELEX 996404 EASYLINK 62968934 CABLE OMEGA En Espa ol 001 203 359 7803 e mail espanol omega com FAX 001 203 359 7807 info omega com mx Servicing Europe Postbus 8034 1180 LA Amstelveen The Netherlands TEL 31 0 20 3472121 FAX 31 0 20 6434643 Toll Free in Benelux 0800 0993344 e mail sales omegaeng nl Frystatska 184 733 01 Karvin Czech Republic TEL 420 0 59 6311899 FAX 420 0 59 6311114 Toll Free 0800 1 66342 e mail info omegashop cz 11 rue Jacques Cartier 78280 Guyancourt France TEL 33 0 1 61 37 29 00 FAX 33 0 1 30 57 54 27 Toll Free in France 0800 466 342 e mail
8. at the top and bottom are keyed to fit in only one direction Electrical Interface Selection Each of the four ports on the OMG USB SER 4 can be individually configured as an RS 232 RS 422 or RS 485 interface This is selectable via the DIP switches and DIP shunts Each of the switch positions is described on the following page OMG USB SER 4 Page 4 Configuration Switch Descriptions PU PD SW2 Figure 1 Switches SW2 and SW4 485 option OFF for 422 OFF No effect ON Connects TX to RX for two wire operation 485 option OFF for 422 OFF No effect ON Connects TX to RX for two wire operation 485 option OFF for 422 OFF No effect ON Adds a 1 K ohm pull up resistor to RX 485 option OFF for 422 OFF No effect ON Adds a 1 K ohm pull down resistor to RX 422 and 485 option OFF No effect ON Adds a 120 ohm termination resistor between RX and RX OMG USB SER 4 Page 5 Configuration Switch Examples 485 1 NE 1 485 2 NE2 Figure 2 RS422 485 Interface Configuration 485 Mode Selection OFF 422 Mode The transmitter lines TX and TX are always driven ON 485 Mode The transmitter lines TX and TX are switched to high impedance when the device is not actively transmitting data NE 485 option OFF for 422 OFF The receiver is always enabled In a two wire setup the receiver will echo back all transmitted data ON The receiver is disabled when the transmitter is enabled In a
9. bration improper specification misapplication misuse or other operating conditions outside of OMEGA S control Components which wear are not warranted including but not limited to contact points fuses and triacs OMEGA is pleased to offer suggestions on the use of its various products However OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any damages that result from the use of its products in accordance with information provided by OMEGA either verbal or written OMEGA warrants only that the parts manufactured by it will be as specified and free of defects OMEGA MAKES NO OTHER WARRANTIES OR REPRESENTATIONS OF ANY KIND WHATSOEVER EXPRESS OR IMPLIED EXCEPT THAT OFTITLE AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED LIMITATION OF LIABILITY The remedies of purchaser set forth herein are exclusive and the total liability of OMEGA with respect to this order whether based on contract warranty negligence indemnification strict liability or otherwise shall not exceed the purchase price of the component upon which liability is based In no event shall OMEGA be liable for consequential incidental or special damages CONDITIONS Equipment sold by OMEGA is not intended to be used nor shall it be used 1 as a Basic Component under 10 CFR 21 NRC used in or with any nuclear installation or activity or 2 in med
10. by unauthorized modifications of this equipment or the substitution of attachment of connecting cables and equipment other than those specified by Omega Engineering Such unauthorized modifications substitutions or attachments may void the user s authority to operate the equipment The correction of interference caused by such unauthorized modifications substitutions or attachments will be the responsibility of the user Always use cabling provided with this product if possible If no cable is provided or if an alternate cable is required use high quality shielded cabling to maintain compliance with FCC directives Canadian Radio Interference Regulations This Class B digital apparatus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet Appareil num rique de la classe B respecte toutes les exigences de R glement sur le mat riel du Canada OMG USB SER 4 Page 15 Appendix E Compliance Notices EMC Directive Statement Products bearing the CE Label fulfill the requirements of the EMC directive 89 336 EEC and of the low voltage directive 73 23 EEC issued by the European Commission To obey these directives the following European standards must be met EN55022 Class B Limits and methods of measurement of radio nterference characteristics of information technology equipment uas EN55024 Information technology equipment Immunity characteristics Limits and methods of mea
11. ed through a simple and straightforward programming interface Character boundaries for asynchronous communications are defined by a starting bit followed by a pre defined number of data bits 5 6 7 or 8 The end of the character is defined by the transmission of a pre defined number of stop bits usually 1 1 5 or 2 An extra bit used for error detection is often appended before the stop bits Idle state of Odd Even gis Pt 8 Data Bits _______ey el sed Remain le or 1 2 ser I 3 ay ane NOS a do oe Oe eee I I I 1 I ler BSP 4 0 demme td mb med i i lees rim tt fom 150g lan 2 al Figure 4 Asynchronous Communications Bit Diagram This special bit is called the parity bit Parity is a simple method of determining if a data bit has been lost or corrupted during transmission There are several methods for implementing a parity check to guard against data corruption Common methods are called E ven Parity or O dd Parity Sometimes parity is not used to detect errors on the data stream This is refereed to as N o parity Because each bit in asynchronous communications is sent consecutively it is easy to generalize asynchronous communications by stating that each character is wrapped framed by pre defined bits to mark the beginning and end of the serial transmis sion of the character The data rate and communication parameters for asynchronous communications have to be the same at both the transmitting and receiving ends
12. eesescesescesceecstescneeeeeeeneees FEATURES u rnrn E EN ETNA E EREET 8 CONNECTOR PIN ASSIGNMENTS cccccccccsssccssssssssscssssscsssesesssssssscesens 8 RS 422 485 DB 9 Male 8 RS 232 DN eee 8 ENVIRONMENTAL SPECIFICATIONS cccsccsesccseeseseeseseeseeeeseeeeeeeaeeeeeees 9 MANUFACTURING uunusg uge Gems 9 POWER CONSUMPTION a a ar eree rei eoe aeaeo oe renia Eok er Eea 9 MEAN TIME BETWEEN FAILURES MTBP rrrorrorrrrrvronrrrervrnrrrenernr 9 PHYSICAL DIMENSIONG sccsceceseeseseesesecseeeesesceseeaeseeseaeseeseeeeeeeaeseeeees 9 APPENDIX TROUBLESHOOTING ccscssssssssccsssssssssscssreee LO APPENDIX B HOW TO GET ASSISTANCE cccccscccsscccccseseeed APPENDIX C ELECTRICAL INTERFACE ccscssssssssssesesesseosee L2 APPENDIX D ASYNCHRONOUS COMMUNICATIONS 000000014 APPENDIX E COMPLIANCE NOTICES scsecscscsssscsesseseeeeeere 15 FEDERAL COMMUNICATIONS COMMISSION STATEMENT 15 CANADIAN RADIO INTERFERENCE REGULATIONG ccccscceeeeeess 15 EMC DIRECTIVE STATEMENT ccccsccsscssesscssessessesscescescesssesecescnsenss 16 Figures Figure 1 Switches SW2 and SW eessseseeesssssevesseeseeensneseeessnesenvnsnesenensavseeessnesene 5 Figure 2 RS422 485 Interface Configuration 6 Figure 3 Electrical Interface Configuration scsscsscssssssssssssssssseseseesers 7 Figure 4 Asynchronous Communications Bit Diagram c esesesevesesesevesssese 14 Intr
13. ge Width 5 32 inches 13 51 cm Package Height 1 50 inches 3 81 cm OMG USB SER 4 Page 9 Appendix A Troubleshooting Appendix A Troubleshooting Serial Utility test software is supplied with the adapter and will be used in the troubleshooting procedures Using this software and following these simple steps most common problems can be eliminated without the need to call Technical Support 1 If your adapter isn t working first check to make sure that USB support is enabled in the System BIOS and it is functioning properly in the operating system This can be done by using either the Windows 98 ME or Windows 2000 Device Manager Ensure that the software has been installed on the machine so that the necessary files are in place to complete the installation When the OMG USB SER 4 is configured properly the USB Enabled LED E will be lit This should allow you to use the WinSSD utility and the supplied loopback plug to check communications The supplied loopback plug connects TD to RD If you decide to test the Modem Control Signals a full pin loopback plug will be required Details on loopback plugs are included on WinSSD Contact Omega if you need further assistance When testing the OMG USB SER 4 in loopback mode you should see the port LED s flashing as well as seeing echoed data on the screen The loopback test first transmits a HEX pattern 55AA and then a ASCII string of data If this test passes then the O
14. ic levels are defined by the difference in voltage between a pair of outputs or inputs In contrast a single ended interface for example RS 232 defines the logic levels as the difference in voltage between a single signal and a common ground connection Differential interfaces are typically more immune to noise or voltage spikes that may occur on the communication lines Differential interfaces also have greater drive capabilities that allow for longer cable lengths RS 422 is rated up to 10 Megabits per second and can have cabling 4000 feet long RS 422 also defines driver and receiver electrical characteristics that will allow driver and up to 32 receivers on the line at once RS 422 signal levels range from 0 to 5 volts RS 422 does not define a physical connector OMG USB SER 4 Page 12 Appendix C Electrical Interface RS 485 RS 485 is backwardly compatible with RS 422 however it is optimized for partyline or multi drop applications The output of the RS 422 485 driver is capable of being Active enabled or Tri State disabled This capability allows multiple ports to be connected in a multi drop bus and selectively polled RS 485 allows cable lengths up to 4000 feet and data rates up to 10 Megabits per second The signal levels for RS 485 are the same as those defined by RS 422 RS 485 has electrical characteristics that allow for 32 drivers and 32 receivers to be connected to one line This interface is ideal for multi drop or ne
15. ical applications or used on humans Should any Product s be used in or with any nuclear installation or activity medical application used on humans or misused in any way OMEGA assumes no responsibility as set forth in our basic WARRANTY DISCLAIMER language and additionally purchaser will indemnify OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the Product s in such a manner RETURN REQUESTS INQUIRIES Direct all warranty and repair requests inquiries to the OMEGA Customer Service Department BEFORE RETURNING ANY PRODUCT S TO OMEGA PURCHASER MUST OBTAIN AN AUTHORIZED RETURN AR NUMBER FROM OMEGA S CUSTOMER SERVICE DEPARTMENT IN ORDER TO AVOID PROCESSING DELAYS The assigned AR number should then be marked on the outside of the return package and on any correspondence The purchaser is responsible for shipping charges freight insurance and proper packaging to prevent breakage in transit FOR WARRANTY RETURNS please have the FOR NON WARRANTY REPAIRS consult OMEGA following information available BEFORE for current repair charges Have the following contacting OMEGA information available BEFORE contacting OMEGA L Purchase Order number under which the product 1 Purchase Order number to cover the COST was PURCHASED of the repair 2 Model and serial number of the product under 2 Model and serial number of the product and warranty and 3 Repair instructions and or specific proble
16. ms 3 Repair instructions and or specific problems relative to the product relative to the product OMEGA s policy is to make running changes not model changes whenever an improvement is possible This affords our customers the latest in technology and engineering OMEGA is a registered trademark of OMEGA ENGINEERING INC Copyright 2002 OMEGA ENGINEERING INC All rights reserved This document may not be copied photocopied reproduced translated or reduced to any electronic medium or machine readable form in whole or in part without the prior written consent of OMEGA ENGINEERING INC Where Do I Find Everything I Need for Process Measurement and Control OMEGA Of Course Shop online at www omega com TEMPERATURE Zg Thermocouple RTD amp Thermistor Probes Connectors Panels amp Assemblies 4 Wire Thermocouple RTD amp Thermistor A Calibrators amp Ice Point References A Recorders Controllers amp Process Monitors 4 Infrared Pyrometers PRESSURE STRAIN AND FORCE 4 Transducers amp Strain Gages A Load Cells amp Pressure Gages 4 Displacement Transducers A Instrumentation amp Accessories FLOW LEVEL 4 Rotameters Gas Mass Flowmeters amp Flow Computers WF Air Velocity Indicators A Turbine Paddlewheel Systems A Totalizers amp Batch Controllers pH CONDUCTIVITY l pH Electrodes Testers amp Accessories 4 Benchtop Laboratory Meters 4 Controllers Calibrators Simulators amp
17. nterface Appendix C Electrical Interface RS 232 Quite possibly the most widely used communication standard is RS 232 This implementation has been defined and revised several times and is often referred to as RS 232 or EIA TIA 232 The IBM PC computer defined the RS 232 port on a 9 pin D sub connector and subsequently the EIA TIA approved this implementation as the EIA TIA 574 standard This standard is defined as the 9 Position Non Synchronous Interface between Data Terminal Equipment and Data Circuit Terminating Equipment Employing Serial Binary Data Interchange Both implementations are in wide spread use and will be referred to as RS 232 in this document RS 232 is capable of operating at data rates up to 20 Kbps at distances less than 50 ft The absolute maximum data rate may vary due to line conditions and cable lengths RS 232 is a single ended or unbalanced interface meaning that a single electrical signal is compared to a common signal ground to determine binary logic states The RS 232 and the EIA TIA 574 specification define two types of interface circuits Data Terminal Equipment DTE and Data Circuit Terminating Equipment DCE The OMG USB SER 4 is a DTE device RS 422 The RS 422 specification defines the electrical characteristics of balanced voltage digital interface circuits RS 422 is a differential interface that defines voltage levels and driver receiver electrical specifications On a differential interface log
18. oduction Introduction Overview The OMG USB SER 4 equips the PC with 4 USB to RS 232 422 485 Asynchronous serial ports providing a versatile interface for common serial needs The advantage of this product over more traditional approaches is that it does not require opening the computer case nor does it require resources such as I O ports or IRQ s It does require a system that supports USB both in terms of hardware and operating system What s Included The OMG USB SER 4 is shipped with the following items If any of these items is missing or damaged contact the supplier e OMG USB SER 4 USB to RS 232 422 485 Serial I O Adapter e USB Cable Part Number CA179 for Connecting to Upstream Host Hub e Software OMG USB SER 4 Page 1 Installation Installation Operating System Installation Choose Install Software at the beginning of the CD and install SeaCOM System Installation The screen captures below are taken from a Windows installation Your particular operating system may differ slightly from what is shown based on your version of Windows The OMG USB SER 4 can be connected to any upstream type A port either at the PC host or an upstream hub The OMG USB SER 4 is hot pluggable meaning there is no need to power down your computer prior to installation Connect the OMG USB SER 4 to an upstream host or hub The New Hardware Found wizard will now proceed to locate the appropriate drivers These
19. programmable baud rate data format 128 byte Dual Port TX Buffer and 384 byte Dual Port RX Buffer The RS 232 422 485 transceiver supports data rates up to 921 6K baud for RS 422 485 and 460 8K baud for RS 232 Features e Hot pluggable device that does not require opening the case e No system resources are required i e I O ports or IRQ s e LED status indicators for USB Enabled and port activity Connector Pin Assignments RS 422 485 DB 9 Male a Input Clear To Send Positive Clear To Send Negative RS 232 DB 9 Male Pin Oooo RTS Input Pin TX Transmit Dat PRISE Request To Send Positive 6 RT i 9 Fr X R c D D TS TR f i 1 OMG USB SER 4 Page 8 Specifications Specifications Environmental Specifications Temperature Range 0 to 50 C 20 to 70 C 32 to 122 F 4 to 158 F Humidity Range 10 to 90 R H 10 to 90 R H Non Condensing Non Condensing Manufacturing e All Printed Circuit boards are built to UL 94V0 rating and are 100 electrically tested These printed circuit boards are solder mask over bare copper or solder mask over tin nickel Power Consumption This device is a high power USB device It must be plugged into the USB root hub or a self powered hub capable of supplying 500 mA per port Mean Time Between Failures MTBF Greater than 150 000 hours Calculated Physical Dimensions Package Length 7 06 inches 17 93 cm Packa
20. surement EN60950 IEC950 Safety of information technology equipment including electrical business equipment Always use cabling provided with this product if possible If no cable is provided or if an alternate cable is required use high quality shielded cabling to maintain compliance with EMC directives OMG USB SER 4 Page 16 USA WARRANTY DISCLAIMER OMEGA ENGINEERING INC warrants this unit to be free of defects in materials and workmanship for a period of 13 months from date of purchase OMEGA S WARRANTY adds an additional one 1 month grace period to the normal one 1 year product warranty to cover handling and shipping time This ensures that OM EGA customers receive maximum coverage on each product If the unit malfunctions it must be returned to the factory for evaluation OMEGA s Customer Service Department will issue an Authorized Return AR number immediately upon phone or written request Upon examination by OMEGA if the unit is found to be defective it will be repaired or replaced at no charge OMEGA s WARRANTY does not apply to defects resulting from any action of the purchaser includ ing but not limited to mishandling improper interfacing operation outside of design limits improper repair or unauthorized modification This WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of having been damaged as a result of excessive corrosion or current heat moisture or vi
21. twork environments RS 485 tri state driver not dual state will allow the electrical presence of the driver to be removed from the line Only one driver may be active at a time and the other driver s must be tri stated RS 485 can be cabled in two ways two wire and four wire mode Two wire mode does not allow for full duplex communication and requires that data be transferred in only one direction at a time For half duplex operation the two transmit pins should be connected to the two receive pins Tx to Rx and Tx to Rx Four wire mode allows full duplex data transfers RS 485 does not define a connector pin out or a set of modem control signals RS 485 does not define a physical connector OMG USB SER 4 Page 13 Appendix D Asynchronous Communications Appendix D Asynchronous Communications Serial data communications implies that individual bits of a character are transmitted consecutively to a receiver that assembles the bits back into a character Data rate error checking handshaking and character framing start stop bits are pre defined and must correspond at both the transmitting and receiving ends Asynchronous communications is the standard means of serial data communication for PC compatibles and PS 2 computers The original PC was equipped with a communication or COM port that was designed around an 8250 Universal Asynchronous Receiver Transmitter UART This device allows asynchronous serial data to be transferr
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