Cordex®CXCHPControllerSoftwareManual|24-Cordex®CXCHPcontrollerreferenceguide
OnlyUSBmassstoragedevicesthathavebeenformattedwithaFAT32filesystemarefullysupportedfor
useintheUSBports.USBdriveswiththeNTFSfilesystemwillnotwork.
USBportscanbedisabledtoprovideenhancedanti-tamperingaboveandbeyondthenormallocal
physicalsecurityofatypicalinstallation.Whendisabled,thenoUSBdevicewillfunctionwhenplugged
inandshouldthisberequired,gotoController > Settings > User Interfaceandinthe User Interface
tableyoucandisableandenableUSBports.Tosuccessfullydisabletheports,firstensurethatthere
arenoUSBdevicespluggedin.Failuretodosomaypreventaportfrombeingdisabled,asitisinuse;
aresetorpowercyclemayberequiredbeforeanotherattempttodisablewillbesuccessful.Adisabled
USBportshouldprovidenopowertothepluggedindevice.IfthedevicehasanLEDonit,thismaybe
usedtodetermineiftheportisactuallydisabled.
24.2.3. CAN ports
Introduction to CAN for the Cordex® CXC HP controller
CANisusedbythecontrollertodiscover,collectdatafrom,control,andconfigurethepowermodules
andI/O(ADIO)modulesinthepowersystem.ThecontrollerhastwouptoCANbuses,eachofwhichcan
controlupto127powerandADIOmodules.
What is a CAN bus?
Acontrollerareanetwork(CAN)referstoanetworkofdevicesthatcommunicateusingtheCANserial
protocoltosupportdistributedreal-timecontrol.
How do CAN bus modules communicate?
ACANbususestwodedicatedwiresforcommunicationcalledCANhighandCANlow.WhentheCAN
busisidle,bothlinescarry2.5volts.Whendatabitsarebeingtransmitted,theCANhighlinegoesto3.75
voltsandtheCANlowdropsto1.25volts,therebygeneratinga2.5voltsdifferencebetweenthelines.
Sincecommunicationreliesonavoltagedifferencebetweenthetwobuslines,theCANbusisinsensitive
toinductivespikes,electricalfieldsorothernoise.ThismakesCANbusareliablechoicefornetworked
communicationsinelectricallynoisyenvironments.
Figure 24-1 CANdifferentialsignaling
Volts
3.75
2.5
1.25
Data
1
0
1
Time
CAN Low
CAN High
2.5V
CAN network topology
ACANnetworkusesatwistedpaircabletotransmitthedifferentialsignals,terminatedatbothendswith
120ohmresistors.
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