Instruction manual

ManualsBrandsClipsal ManualsComputer equipment5500CN Series

C-Bus By Demand 3

Training Manual 13

Soforthisexampleyouwilltypein16(forSubnetMask255.255.0.0)andpressenter.

 13) Keeppressingenteruntilyougettothemainmenu.

 14) Onceatthemainmenu,select1(Channel1Configuration)andpressenter.

 15) KeeppressingenteruntilyoureachthePortNumberparameter.

 16) TypeinthePortNumbe

r10001andpressenter.

 17) Keeppressingenteruntilyoureturntothemainmenu.

 18) Press9 tosaveandexit.

 19) Whilstinthecommandprompt,typeinping10.120.120.120andpressente

r.

YoushouldnowbeabletopingyourCNI.

1.6

Bandwidth Usage

Theamountof bandwidth onanEthernet networkthatwould be used byaCNIisverysmall.

The CNI protocol is similar to a telne

t protocol. Every single character sent to a CNI is placed

intoitsownEthernetpacketandsentoff.Thismeansthereislo

tsofoverhead(about50bytesfor

everypacket).

This means that the Ethernet bandwidth used is roughly about 50 times that of C‐Bus. The

C‐

Bus PC Interface will send out characters at a baud rate of 9600 bits per second or 960

characterspersecond.This willcreateabout 960packetsper secondonEthernet, atroughly 50

bytesperpacket.Therefore:‐

(50bytesperpacket)*(960packetspersecond)=48,000bytespersecond.

C‐Bus itself is only 4000 bits per second, which equates to approximately  400 characters per

second.TheratethroughthePCIwon’texceedthisbymuch.

OnEthernet,wehave3commonstandardsmeasuredinbitspersecond:

•10Mb •100Mb •1000Mb



OnEthernetyoucannotgetthequotedratesbecauseofthecollisiondetectionsystemused.The

maximumutilisationisabout20%ofthetheoreticalspeed.

Converting to bytes (assuming 10 bits  / character), and scaling by the typical ma

x usage, this

givescapacitiesrespectivelyof:‐

•200kBps •2MBps •20MBps



So the bandwidth used for a C‐Bus Network Interface (CNI) in the absolute worst case where

everythingisgoingfullspeedwillbe:‐

Fora10Mbnetworkbandwidth

 48,000(bytes)/200,000(bytes)*100=24%

Fora100Mbnetworkbandwidth 48,000(bytes)/2,000,000(bytes)*100=2.4%

Fora1000Mbnetworkbandwidth 48,000(bytes)/20,000,000(bytes)*100=0.24%



IfusingmorethanoneCNI,thefiguresaboveneedtobemultipliedbythenumberofCNI’s.

Thisisnotasustainedbandwidth.Itisassumedthatitisawors

tcaseburstonanalready

congestedEthernetnetwork.Inpracticeitwillbelessthanthis.