National Instruments PCI-8430 - Page 31

ExpressCardKits
TheExpressCardserialhardwaregivesyouavarietyofsolutionsfor
serialcommunication.TheExpressCard-8420interfaceworkswiththe
RS-232protocol,andtheExpressCard-8421interfaceworkswiththeRS-
422andRS-485protocols.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.
TheExpressCard-8420andExpressCard-8421areavailablewithtwo
ports.AllExpressCardcardsincludecablesforeachportthatterminates
inastandardDB-9connector.Throughoutthishelpfile,ExpressCard
serialinterfacesreferstoallversionsoftheinterfaces.
TheRS-232portsareDTE.IntheRS-232specification,DataTerminal
Equipment(DTE)andDataCommunicationsEquipment(DCE)referto
thetypesofequipmentoneitherendofaserialconnection.Ingeneral,
DTEandDCErefertocomputerequipmentandmodems,respectively.
FormoreinformationaboutcablingaRS-232porttootherdevices,refer
toRS-232DTEvs.DCE.
TheRS-485portssupport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.
AllExpressCard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)bufferstoreducesusceptibilitytointerrupt
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.
ExpressCardBoardNamesandDescriptions
ExpressCard
BoardName
Description
ExpressCard-8420 RS-232twoport
ExpressCard-8421 RS-485twoport