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8
MITSUBISHI ELECTRIC
MELSEC AnS/QnAS
SYSTEM DESCRIPTION
Systemstructure
TheCPUandmodulesareheldinabase
unitwhichhasaninternalbusconnection
forcommunicationbetweentheindividual
modulesandtheCPU.Thepowersupply
modulewhichsuppliesthevoltageforthe
entiresystemisalsoinstalledonthisbase
unit.
Themainbaseunitsareavailablein4dif-
ferentversionswith2to8moduleslots.
Eachbaseunitcanbesupplementedby
meansofanextensionbaseunit,providing
additionalslots.
Ifyouwishtokeepopentheoptionofsub-
sequentextensionofyourPLCorifyou
havefreeslotsonyourmainbaseunit,you
caninsertdummymoduleshere.They
servetoprotectthefreeslotsfromsoiling
orfrommechanicaleffectsbutcanalsobe
usedforreservingI/Opoints.
Forcablinglargersystemsandmachines-
e.g.inamodulardesign-theuseofremote
I/Omodulesoffersadditionalcommunica-
tionsfacilities.Thesemodulesarecon-
nectedbymeansofashieldedtwo-wire
cable.
Extension
Themainbaseunitandextensionbase
unitsaresimplyconnectedtooneanother
byextensioncables.Theseconnecting
cablesalsosupplytheextensionbaseunits
withtheoperatingvoltageof5VDC.
Uptothreeextensionbaseunitscanbe
connectedtoamainbaseunit.Theexten-
sionmaybeinthehorizontalorvertical
direction.
Whenchoosingthepowersupplymodule,
thetotalpowerconsumptionoftheI/O
modules,ofthespecialfunctionmodules
andoftheperipheralsmustbetakeninto
account. Ifnecessary,anextensionbase
unitwithafurtherpowersupplymodule
shouldbeused.
BaseunitsoftheMELSECAnA/AnUseries
canalsobecombinedwiththeAnSseries
usingaspecialcable.
DigitalI/Omodule
Specialfunctionmodule
Powersupply
module
CPUmodule
Memory cassette
Key switch
Programming
interface
Protective
cover
for
removable
terminal
block
Baseunit
Backup
battery
Interface for
extension
base unit
Interface for
extension
base unit
Main base unit
Extension 1
Extension 2
Extension 3
Configuration
BASICS
Q
A
Structure and Handling