National Instruments PCI-8430 - Page 28

USBKits
TheUSBserialhardwaregivesyouavarietyofsolutionsforserial
communication.TheUSB-232hardwareworkswiththeRS-232interface
standard,andtheUSB-485hardwareworkswiththeRS-422andRS-485
interfacestandards.YoucanusetheRS-232portsforserial
communicationuptodistancesof50ft.YoucanconnecttheRS-485
portstoupto31devicesusingserialcablelengthsupto4,000ft.
Additionally,theUSBserialhardwareisavailableinone-port,two-port,
andfour-portversions.AllversionsuseDB-9connectors.Throughoutthis
helpfile,USBserialhardwarereferstoallversionsoftheUSBserial
hardware.
TheUSB-232twoandfour-porthardwaresupportsthreehardware
transceivermodessupportingbothDTEandDCEconfigurations.For
moreinformationabouttransceivercontrolmodes,refertoUSB-232
TransceiverModes.
TheRS-485hardwaresupportsfourhardwaretransceivercontrolmodes
forreliablecommunicationwithtwoandfour-wiredevices.Formore
informationabouttransceivercontrolmodes,refertoRS-485Transceiver
Control.Inaddition,theUSB-485hardwaresupportsprogrammatic
controlofthebiasresistors.Formoreinformation,refertoUSB-485
ProgrammaticallyControlledBiasResistors.
AllUSBserialhardwareusesstandard16550-compatibleUARTs
(UniversalAsynchronousReceiver/Transmitters)forcomplete
compatibilitywithstandardPCCOMports.Theserialhardwarecontains
FIFO(First-In-First-Out)andUSBbufferstoreducesusceptibilityto
systemlatencyforfastertransmissionrates.FullPlugandPlay
compatibilityallowsswitchlessconfigurationandinstallation.Formore
informationabouttheserialhardwarespecificationsandoperating
conditions,refertotheNISerialHardwareGuide.