Rocstor Rocpro 850 - Introduction to Interfaces (Ports) and Cables; Firewire (IEEE 1394)


37ROCSTOR‐ROCPRO850usermanual
Introductions:Interfaces(ports)andCables

FireWireisAppleInc.’sbrandnamefortheIEEE1394
interface(althoughthe1394standardalsodefinesa
backplaneinterface).FireWireisalsoknownasi.LINK
(Sony’sname)andDV(Panasonic’sname,nottobe
confusedwithDVcamcordertapes).Itisaserialbus
interfacestandardforhigh‐speedcommunicationsand
isochronousreal‐timedatatransfer,frequentlyusedina
personalcomputeranddigitalaudio/digitalvideo.



Standardsandversions

FireWire400(IEEE1394)6‐Pinconnectorcantransferdatabetween
devicesat100,200,or400Mbits/shalf‐duplexdatarates(theactual
transferratesare98.304,196.608,and393.216Mbits/s,i.e.12.288,
24.576and49.152megabytespersecondrespectively).Thesedifferent
transfermodesarecommonlyreferredtoasS100,S200,andS400.

Cablelengthislimitedto14.8ft(4.5meters),althoughupto16cablescanbedaisy‐chained
usingactiverepeaters,externalhubs,orinternalhubsoftenpresentinFireWireequipment.
TheS400standardlimitsanyconfiguration'smaximumcablelengthto230Ft(72meters.)The
6‐pinconnectoriscommonlyfoundondesktopcomputersandcansupplytheconnected
devicewithpower.

The6‐pinpoweredconnectoraddspoweroutputtosupportexternaldevices.Typicallyadevice
canpullabout7to8wattsfromtheport.However,thevoltagevariessignificantlyfrom
differentdevices.Voltageisspecifiedasunregulatedandshouldnominallybeabout25volts
(range24to30).Apple'simplementationonlaptopsistypicallyrelatedtobatterypowerand
canbeaslowas9Vbutmorelikelyabout12V.

FireWire400(IEEE1394a)
1394aalsostandardizedthe4pinconnectoralreadywidelyinuse.The4‐
pinversionisusedonmanyconsumerdevicessuchascamcorders,some
laptopsandothersmallFireWiredevices.Thoughfullydatacompatible
with6‐pininterfaces,itlackspowerconnectors.







