What is a ladder diagram? Ladder diagram programming

Ladder diagram is the most used graphic programming language, it is called the first programming language of PLC. Ladder diagram and electrical control system circuit diagram is very similar, with intuitive and easy to understand the advantages, it is easy to be mastered by the factory electrical personnel, especially suitable for switching logic control. Ladder diagram is often referred to as the circuit or program, the design of ladder diagram is called programming.

1. http://www.plchelpcenter.com
Ladderdiagramisthemostusedgraphicprogramminglanguage,itis
calledthefirstprogramminglanguageofPLC.Ladderdiagramandelectrical
controlsystemcircuitdiagramisverysimilar,withintuitiveandeasyto
understandtheadvantages,itiseasytobemasteredbythefactoryelectrical
personnel,especiallysuitableforswitchinglogiccontrol.Ladderdiagramis
oftenreferredtoasthecircuitorprogram,thedesignofladderdiagramis
calledprogramming.
Ladderdiagramprogramming,usethefollowingfourbasicnames:
1,SoftRelay
SomeofPLCladderdiagramprogrammingelementfollowsthenameofthe
relay,suchasinputrelay,outputrelay,internalauxiliaryrelay,etc.,theyare
notrealphysicalrelays,thataresomestorageunit(softrelay),astorageunit
foreachsoftrelayandPLCmemoryimageregister.Thestorageunitifthe“1”
state,theladderdiagramofthecorrespondingsoftrelaycoilenergized,the
normallyopencontactisturnedon,normallyclosedcontactisdisconnected,
thisisthesoftrelay“1”or“on”state.Ifthememorycellis“0”,thestateofthe
coilandcontactofthecorrespondingsoftrelayisincontrasttotheabove,this
issoftrelayis“0”or“OFF”.Theuseofthese“softrelay”isoftencalledtoas
theprogrammingelement.
2,FlowPower
Figure,contacts1and2isswitchedon,thereisasupposed“conceptof
current“or“PowerFlow),flowingfromlefttoright,thedirectionand
executionwhenauserprogramisconsistentwiththeorderofthelogical
operations.
Powerflowcanonlyflowfromlefttoright.Usingtheconceptofenergyflow,
canhelpustobetterunderstandandanalyzetheladderdiagram.
Figure,maybetwodirectionsofpowerflowthroughthecontacts5(through
contactpoints1,5,4orcontactpoints3,5,2),whichdonotmeetthe
principlesofenergycurrentcanonlyflowfromlefttoright

2. http://www.plchelpcenter.com
A)thewrongladderdiagram
b)thecorrectladderdiagram
3,Busbar
Ladderonbothsidesoftheverticallineiscalledpublic(Busbar),.Inthe
analysisofladderlogic,inordertoborrowtherelaycircuitanalysismethod,
thereareconceivablebetweentheleftandrightsidebus(leftbusbarandright
busbar)aleftandrightpositivenegativeDCsupplyvoltage,the“powerflow
betweenbusbar“fromlefttoright.Youcannotdrawrightbusbar.
4,Theladderlogicsolution
Accordingtothestateandthelogicrelationofeachcontactintheladder
diagram,thestateoftheprogrammingelementscorrespondingtoeachcoilin
thediagramisobtained,iscalledlogicalsolutionofladderdiagram.
Ladderlogicsolutionswereconsideredbyfromlefttoright,toptobottom
sequence.Theresultsoftheresolver,canbeimmediatelyutilizedbythelogic
solverbehind.–Logicbebasedontheinputimageregistervalues,ratherthan
resolvertheinstantaneousstateoftheexternalinputcontactscarriedout.