Omega Engineering OMG-CONV-485-ISO manual Appendix a Troubleshooting

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Appendix A - Troubleshooting

Appendix A - Troubleshooting

Serial Utility test software is supplied with the adapter and will be used in the troubleshooting procedures. By using this software and following these simple steps, most common problems can be eliminated without the need to call Technical Support.

1.The OMG-CONV-485-ISO is a level converter and therefore requires no system resources such as I/O ports or IRQ’s. The I/O resources of the host RS-232 COM: port will be used to access the port.

2.If you are experiencing problems, a good starting point is to verify proper operation of the host RS-232 COM: port. Connect the host port TX and RX lines and use the WinSSD utility to perform a loopback test. If you cannot open the host port, ensure that it is enabled in the System BIOS. If using a Plug ‘n’ Play operating system, verify that it is recognized by the system.

3.If the host RS-232 port is working properly, verify that the OMG-CONV-485- ISO is configured correctly for your application based on the ‘Card Setup’ section earlier in this manual. After attaching the OMG-CONV-485-ISO, you may perform a loopback test by connecting TX+ to RX+ and TX- to RX-. Keep in mind that this test will fail should you have dip switch SW2 position 6 on. This forces the OMG-CONV-485-ISO into ‘No Echo’ mode and will prevent the loopback test from passing. For loopback purposes, always have dip switch SW2 position 6 off even if you will use No Echo in your actual application.

4.During the loopback test, pay attention to the TX and RX leds as both of these should be on. Failure of one or both of these to be on would indicate a hardware problem on the adapter.

OMG-CONV-485-ISO

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Contents User’sGuide Canada MexicoBenelux Czech RepublicContents Figures Factory Default Settings IntroductionOverview What’s IncludedCard Setup RS-485 Enable ModesCommunication Mode Examples Dip switch SW1 Dip switch SW1, RS-422Line Termination and Receiver Echo Off/On FunctionElectrical Interface Examples Dip switch SW2 RS-422 with Termination and Receiver EchoOperating System Installation For Windows Users RS-485 Two-Wire and RS-485 Four-Wire Slave Installation Other Operating Systems System Installation Please NoteTechnical Description Connector Pin Assignments RS-232 Signals DB-25 FemaleRS-422/485 Pin Assignments 6 Position Screw Terminal Specifications Environmental SpecificationsPhysical Dimensions ManufacturingAppendix a Troubleshooting Appendix B How To Get Assistance RS-232 Appendix C Electrical InterfaceRS-422 RS-485 What is Ground Loop? Appendix D Ground Loop PhenomenonCabling Recommendations Isolated AdapterAsynchronous Communications Bit Diagram Appendix E Asynchronous Communications688 Appendix F Silk-ScreenAppendix G Compliance Notices WARRANTY/DISCLAIMER Temperature