National Instruments PCI-8430 - Page 194

Whatistherelationshipbetweenbitsper
second,throughput,andbusutilization?
Thetermbitspersecond(bps)referstothebitrateofdatatransfer,with
1/bpsbeingthelengthoftimerequiredtotransmitonebit.
Throughputistheactualdatatransfermeasuredby
amountofdatatransmittedtimerequiredtotransmit
Busutilizationisthepercentageoftimethattheserialbusisactively
transmittingdata.Becauseawiderangeoffactorssuchasflowcontrol,
processorlatency,anddevicearchitecturecanaffectserialperformance,
busutilizationoftenisnot100percent.Inaddition,thereisoverhead
associatedwithserialcommunicationintheformofstartbits,stopbits,
andparitybits.Thisoverheadreducesthethroughputby20–30percent.
Thus,theactualdatathroughputcanbeconsiderablylessthanthebits
persecondsetting.