⚡ Sparky Ed
Ask Sparky about your circuit
I can see the rungs on your screen. Ask me why a coil isn't energizing, how seal-in contacts work, or anything about ladder logic.
Welcome to the PLC Ladder Logic Simulator! Build and simulate industrial ladder logic circuits.
Getting Started
- Click + Rung or load a Scenario
- Drag elements from the left palette onto rungs
- Click Run (or press Space) to start scanning
- Left-click a contact to toggle it manually
Keyboard Shortcuts
- Space - Toggle Run/Stop
- Escape - Close modals/menus
Mouse Controls
- Left-click contact - Toggle manual tag state (while running)
- Right-click element - Edit or Delete context menu
- Double-click coil/element - Open edit dialog
- Click rung number - Add/edit rung comment
- + Branch button - Add parallel path to rung
- x button on branch - Delete that parallel path
Contact Types
- NO - Normally Open: closed (passes) when tag = TRUE
- NC - Normally Closed: closed (passes) when tag = FALSE
- POS - Rising edge one-shot (positive transition)
- NEG - Falling edge one-shot (negative transition)
- OL - Overload relay: NC contact, trips with Trip OL button
Coil Types
- ( ) COIL - Standard output coil, follows rung power
- ( L ) LATCH - Latches tag TRUE when rung energized
- ( U ) UNLATCH - Resets latched tag when rung energized
TON Timer
- Accumulates time while rung power is TRUE
- When accumulator reaches preset, tag_DN goes TRUE
- Resets accumulator when rung power goes FALSE
OL (Overload) Relay
Use Trip OL to simulate a motor overload. The OL contact opens, stopping the motor. Use Reset OL to clear the trip and any latches.
Scenarios
- 1. Start/Stop Motor - Classic 3-wire control
- 2. Forward/Reverse - Interlocked contactors
- 3. TON Timer - On-delay timer
- 4. Latch/Unlatch - Maintained fault memory
- 5. One-Shot POS - Rising edge detection
- 6. Parallel Paths - Multiple start conditions
- 7. Interlock - Safety chain
- 8. Two Timers - Sequential timing
- 9. NC Safety - Fail-safe contacts
- 10. Full System - Combined circuit