Moxa Technologies CP-132U user manual Impedance Matching and Termination Resistors

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Connection Cables and Cables Wiring

Impedance Matching and Termination Resistors

When using RS-422/485 serial communications, an electrical signal that travels through two different resistance junctions in a transmission line will sometimes give rise to signal reflection due to the impedance mismatch. Signal reflection causes signal distortion, which in turn contributes to communication errors. The solution to this problem is to establish the same impedance at the ends of the transmission line, as in the line itself, by terminating the ends of the line with resistors.

CP-132U Series User’s Manual 5-7

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Contents CP-132U Series User’s Manual Trademarks Copyright NoticeDisclaimer Moxa Internet Services Table of Contents Appendix a Page Introduction Termination Resistors Ready for RS-422/485 Industio-The Industrial Multiport Async SolutionOverview Addc Automatic Data Direction Control for RS-485Moxa Serial Comm Tools Introduction PCI SolutionUniversal PCI Operating System SupportPackage Checklist FeaturesHardware Installation CP-132UL-I V2 120 x 64.5 mm CP-132UL Series Block DiagramCP-132U-I V1 120 x 100 mm Hardware InstallationCP-132UL V1 120 x 64.5 mm DIP Switch Port Settings Installing the CP-132UL Series Board Windows Software InstallationInstalling the Driver Software Installation CP-132U Series User’s Manual Software Installation Using Device Manager How to Check the InstallationPort Configuration CP-132U Series User’s Manual Using Event Log Using PCommWindows 2000/XP Select Install from a list or specific 12 CP-132U Series User’s Manual Software Installation 14 CP-132U Series User’s Manual Select Specify a location and then click Next to continue 16 CP-132U Series User’s Manual Software Installation Device Manager Port Configuration 20 CP-132U Series User’s Manual Event Log Moxa PComm UtilityRemoving the Driver Click OK to proceed with the un-installation of the board Windows 95/98 Installing the Driver Installation First Time Driver InstallationWindows Click Other Locations 28 CP-132U Series User’s Manual Windows Software Installation Board and Port ReadyConfiguring the Board and Ports Software Installation Updating the Driver Software Installation Removing the Driver Windows NT 36 CP-132U Series User’s Manual Software Installation 38 CP-132U Series User’s Manual Software Installation Re-Configuring Port Settings Configuring the Board and PortsSoftware Installation Configuring Another CP-168U Board Removing an Existing CP-168U Board Configuration 44 CP-132U Series User’s Manual DOS 46 CP-132U Series User’s Manual Setting up the Driver Port number F5 Group Edit Loading the DriverTxD buffer size RxD buffer sizeUnloading the Driver LinuxSoftware Installation Page Serial Programming Tools PComm InstallationPComm Programming Library Diagnostic for Moxa boards onlyUtilities Terminal Emulator Addc Automatic Data Direction Control RS-485 ProgrammingConnection Cables Cable Wiring RS-422 Interface RS-422/485 Pinouts and Cable WiringRS-485 Interface Pinouts Connection Cables and Cables WiringCP-132UL RS-422 RS-422 Point-to-point RS-422 Broadcasting Cable WiringMultidrop 4-wire RS-485 full-duplex Impedance Matching and Termination Resistors Page General Troubleshooting TroubleshootingSoftware Causes and Solutions COM number of the CP-132U Series conflicts with others Technical ReferenceWindows 95/98 Technical Reference SpecificationsPCI Return Procedure