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Ladder logic (PLC) templates

Ladder - Lift Hall Call and Door Dwell

Nine rungs of a three-storey lift with a registered level-3 hall call and the car standing at level 1: the call latches on rung 2, the clear rung stays unpowered because the car has not arrived, the up command and hoist motor follow, and the 8 s door dwell has never been enabled so the door-open command is dead.

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Template previewLadder logic (PLC)
Lift control - hall call registration, travel and door dwellDECLARED INPUT STATECall_L1 = 0Call_L3 = 1At_L1 = 1At_L3 = 0Door_Closed = 1Overload = 0Safety_OK = 1L1N1Safety chain: governor and gate circuit healthy, car not overloadedTRUESafety_OK1Overload0Lift_Safe12Register the level-3 hall call - it must survive the button releaseTRUECall_L31SCall_Reg_L313Arrival at level 3 cancels the registered callFALSEAt_L30RCall_Reg_L314Travel up while a registered call sits above the carTRUELift_Safe1Call_Reg_L31At_L30Door_Closed1Up_Cmd15Travel down for a call below the carFALSELift_Safe1Call_L10At_L11Door_Closed1Down_Cmd06Hoist motor runs on either direction commandTRUEUp_Cmd1Down_Cmd0Lift_Safe1Hoist_Motor17Door dwell - 8 s held open at a landingFALSEAt_L30TONT_DoorPRE 8 sACC 0 sDN8Doors stay open until the dwell expiresFALSEAt_L30T_Door.DN0Door_Open_Cmd09Level-1 landing indicatorTRUEAt_L11Ind_L119 rungs solved in one scan: 5 true, 4 false. 18 tags, 7 declared as inputs.3 outputs are never energised in this state: 'Down_Cmd', 'T_Door', 'Door_Open_Cmd'.

Make it your own.

title "Lift control - hall call registration, travel and door dwell"
state: Call_L1=0, Call_L3, At_L1, At_L3=0, Door_Closed, Overload=0, Safety_OK

rung "Safety chain: governor and gate circuit healthy, car not overloaded"
  xic Safety_OK
  xio Overload
  ote Lift_Safe

rung "Register the level-3 hall call - it must survive the button release"
  xic Call_L3
  otl Call_Reg_L3

rung "Arrival at level 3 cancels the registered call"
  xic At_L3
  otu Call_Reg_L3

rung "Travel up while a registered call sits above the car"
  xic Lift_Safe
  xic Call_Reg_L3
  xio At_L3
  xic Door_Closed
  ote Up_Cmd

rung "Travel down for a call below the car"
  xic Lift_Safe
  xic Call_L1
  xio At_L1
  xic Door_Closed
  ote Down_Cmd

rung "Hoist motor runs on either direction command"
  branch
    xic Up_Cmd
    xic Down_Cmd
  xic Lift_Safe
  ote Hoist_Motor

rung "Door dwell - 8 s held open at a landing"
  xic At_L3
  ton T_Door preset: 8 accum: 0 unit: s

rung "Doors stay open until the dwell expires"
  xic At_L3
  xio T_Door.DN
  ote Door_Open_Cmd

rung "Level-1 landing indicator"
  xic At_L1
  ote Ind_L1