Basic
20 min

Weld Cell Cycle

weldingclampsequencingfaultsafety
Weld Cell Cycle scenario preview

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Briefing

A welding cell fixture clamps a part, triggers a spot-weld, releases the clamp, and signals cycle complete. An E-stop or any mid-cycle clamp anomaly (clamp neither extended nor retracted within a timeout) latches a fault. The pallet must also be present before clamping begins.

Objectives

  • Sequence: PART_IN_FIXTURE → CLAMP_EXTEND → wait CLAMP_EXTENDED_LS → WELD_START → wait WELD_COMPLETE → CLAMP_RETRACT → wait CLAMP_RETRACTED_LS → pulse CYCLE_COMPLETE_LAMP
  • ESTOP or clamp timeout latches FAULT_LAMP and halts the cell
  • FAULT_LAMP clears only when ESTOP is de-asserted and the cell is reset
  • PALLET_PRESENT must be true before any clamping begins

Hints

  • Use a STEP INT (0=IDLE, 1=CLAMP_EXT, 2=WELDING, 3=CLAMP_RET, 4=DONE)
  • Add a TON (2s) for clamp travel timeout — if CLAMP_EXTENDED_LS / CLAMP_RETRACTED_LS not reached, set fault
  • ESTOP: S= FAULT_BIT on any ESTOP edge, R= only when ESTOP cleared and no clamp anomaly
  • CYCLE_COMPLETE_LAMP: single-scan pulse in step 4, then return to IDLE

I/O Table

Inputs

PART_IN_FIXTURE

Part sensor in fixture

BOOL · %I0.0

CLAMP_EXTENDED_LS

Clamp fully extended limit switch

BOOL · %I0.1

CLAMP_RETRACTED_LS

Clamp fully retracted limit switch

BOOL · %I0.2

WELD_COMPLETE

Weld controller cycle done signal

BOOL · %I0.3

ESTOP

Emergency stop (asserted when hit)

BOOL · %I0.4

PALLET_PRESENT

Pallet present in cell

BOOL · %I0.5

Outputs

CLAMP_EXTEND

Clamp extend solenoid

BOOL · %Q0.0

CLAMP_RETRACT

Clamp retract solenoid

BOOL · %Q0.1

WELD_START

Weld start trigger output

BOOL · %Q0.2

CYCLE_COMPLETE_LAMP

Cycle complete indicator lamp

BOOL · %Q0.3

FAULT_LAMP

Fault indicator lamp

BOOL · %Q0.4

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

  1. #1Full weld cycle completes successfully

    Physics drives all limit switches; CYCLE_COMPLETE_LAMP pulses at end

  2. #2CLAMP_EXTEND fires when PART_IN_FIXTURE is asserted

    With part in fixture and pallet present, clamp extend solenoid energises

  3. #3ESTOP during weld cycle latches FAULT_LAMP

    E-stop halts the cell and latches the fault indicator

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