Ladder - Roller Door Open/Close Interlock

Eight rungs of a loading-bay roller door caught mid-travel with the close command sealed in: the open rung is held off by its own reverse interlock rather than by the buttons, the safety beam is clear so no reverse is latched, and the 180 s courtesy-light TOF is enabled by the moving door so its done bit keeps the bay lamp lit.

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title "Roller door - open/close seal-in with a beam reverse"
state: Open_PB=0, Close_PB=0, Stop_PB, Limit_Open=0, Limit_Closed=0, Beam_Blocked=0, Motor_Close

rung "Safety chain: healthy stop circuit and a clear beam"
  xic Stop_PB
  xio Beam_Blocked
  ote Door_Safe

rung "Open command seals in until the top limit - and never against Close"
  branch
    --] [--Open_PB
    --] [--Reverse_Req
    --] [--Motor_Open
  --] [--Door_Safe
  --]/[--Limit_Open
  --]/[--Motor_Close
  --( )--Motor_Open

rung "Close command seals in until the bottom limit"
  branch
    --] [--Close_PB
    --] [--Motor_Close
  --] [--Door_Safe
  --]/[--Limit_Closed
  --]/[--Motor_Open
  --( )--Motor_Close

rung "A beam break during closing latches a reverse request"
  xic Beam_Blocked
  xic Motor_Close
  otl Reverse_Req

rung "The reverse request clears once the door is fully open"
  xic Limit_Open
  otu Reverse_Req

rung "Courtesy light - 180 s off-delay from the last movement"
  branch
    xic Motor_Open
    xic Motor_Close
  tof T_Light preset: 180 accum: 0 unit: s

rung "Bay lamp follows the off-delay done bit"
  xic T_Light.DN
  ote Bay_Light

rung "Door-closed indicator on the bottom limit"
  xic Limit_Closed
  ote Closed_Lamp