🏢 PLC Elevator System — Siemens TIA Portal V20

A 3-floor elevator control system programmed using Ladder Logic in Siemens TIA Portal V20

The system automates elevator movement, floor selection, door operation, and safety interlocks using a Programmable Logic Controller (PLC), demonstrating real-world industrial automation concepts.

---

📹 Demo Video

The demo video shows the full simulation running in TIA Portal — floor calls, motor direction, door operation, and live tag monitoring in action.

---

📌 Overview

This project implements a complete PLC-based elevator controller for Ground Floor, First Floor, and Second Floor with:

• Floor call handling — floor switches send requests to the PLC
• Direction logic — PLC determines up/down movement based on current floor vs target floor
• Floor switch feedback — memory bit switches confirm elevator position at each floor
• Automatic door control — doors open on arrival, hold via open timer, then close automatically
• Safety interlocks — door button interlock prevents movement while doors are open
• Motor direction control — upward and downward motor outputs with separate travel timers

---

✨ Features

• 3-floor elevator simulation in TIA Portal V20
• Ladder Diagram (LD) programming — IEC 61131-3 standard
• Upward (motor up) and downward (motor down) direction control
• Floor position tracking via memory bits (ground floor sw, first floor sw, second floor sw)
• Direction flags — second to ground and ground to second for travel path logic
• Timer-controlled door open/close sequence
• Separate travel timers — upward lift timer and downward lift timer
• second floor to and ground to second transition timers
• door button memory bit interlock
• Floor indicator lamps — ground, first, and second floor indication outputs

---

📸 Screenshots

Tag table	Watch table

ladder diagram N1

ladder diagram N2

ladder diagram N3

---

🛠️ Technologies Used

Software

Tool	Version	Purpose
Siemens TIA Portal	V20	PLC programming and project environment
PLCSIM	V20	Software simulation — no physical PLC needed

PLC Programming

• Language: Ladder Diagram (LD) — IEC 61131-3
• Target PLC: Siemens S7-1200 / S7-1500 (simulated via PLCSIM V20)

Hardware Components (Physical / Simulated)

Component	Purpose
PLC (S7-1200/1500)	Core controller
Floor Call Switches ×3	Ground / First / Second floor requests
Door Button	Manual door open request
DC Motor / Contactor	Drives elevator up or down
Door Actuator	Opens and closes cabin doors
Floor Indicator Lamps ×3	Ground / First / Second floor indication

---

🏗️ System Architecture

Floor Switches (Ground / First / Second)   ──→   PLC Memory Bits (M)
Door Button

              ↓
      Siemens S7-1200
      Ladder Logic (OB1)
      TIA Portal V20
              ↓

Motor Up (%Q0.3)                           ──→   PLC Digital Outputs (Q)
Motor Down (%Q0.4)
Door Open (%Q0.5)
Door Close (%Q0.6)
Floor Indicator Lamps (%Q0.0 / Q0.1 / Q0.2)

---

🔌 I/O Tag Reference

Digital Outputs (Q)

Tag Name	Address	Description
first floor indication	%Q0.0	First floor position indicator lamp
second floor indication	%Q0.1	Second floor position indicator lamp
ground floor indication	%Q0.2	Ground floor position indicator lamp
motor up	%Q0.3	Elevator motor — upward direction
motor down	%Q0.4	Elevator motor — downward direction
door open	%Q0.5	Door open actuator output
door close	%Q0.6	Door close actuator output

Memory Bits (M) — Internal Flags

Tag Name	Address	Description
first floor sw	%M0.0	Elevator at first floor flag
second floor sw	%M0.1	Elevator at second floor flag
ground floor sw	%M0.2	Elevator at ground floor flag
second to ground	%M0.3	Direction flag — travelling second → ground
ground to second	%M0.4	Direction flag — travelling ground → second
door button	%M0.5	Door open request / door interlock bit

Timers (used in ladder logic)

Tag Name	Type	Description
upward lift timer	TON	Controls upward travel duration
downward lift timer	TON	Controls downward travel duration
close timer	TON	Delay before door closes
open timer	TON	Duration door remains open
second floor to ground	TON	Transition timer — second floor to ground travel
ground to second floor	TON	Transition timer — ground to second travel

---

📁 Repository Structure

PLC-Elevator-System/
│
├── README.md
├── .gitignore
│
├── TIA_Portal_Project/
│   ├── Elevator_System.prx          ← Main TIA Portal V20 project (open this)
│   └── Midway_Checkpoint.prx        ← Intermediate saved version
│
├── Ladder_Diagram/
│   └── (add exported ladder diagram screenshots or PDF here)
│
├── Images/
│   └── (add TIA Portal screenshots here)
│
└── Docs/
    └── IO_Tag_Reference.md          ← Complete I/O tag and address table

---

⚙️ How to Open the Project

Requirements

• Siemens TIA Portal V20 (student/trial license available from Siemens)
• PLCSIM V20 for software simulation (no physical PLC required)

⚠️ .prx files are proprietary Siemens TIA Portal archives. They cannot be opened in older versions like V17 or V19 — you must use V20 or later.

Steps

1. Open Siemens TIA Portal V20
2. Click "Open existing project"
3. Navigate to TIA_Portal_Project/
4. Select Elevator_System.prx → click Open
5. In the Project tree expand PLC_1 → Program blocks → Main [OB1]
6. Double-click to view the ladder logic networks
7. To run simulation: Online → Start simulation (PLCSIM V20 must be running)
8. Open Watch table to monitor live tag values during simulation

---

🔄 System Workflow

System powered on
        ↓
Floor switch pressed (ground / first / second)
        ↓
PLC sets direction flag
(ground to second → motor up)
(second to ground → motor down)
        ↓
Door closed? → Motor activates
        ↓
Upward / downward lift timer runs
        ↓
Target floor switch (memory bit) sets
        ↓
Motor stops
        ↓
Door open output activates
→ Open timer starts
        ↓
Open timer expires
→ Close timer starts → Door closes
        ↓
Ready for next floor call
        ↓
Door button pressed at any time
→ door button (M0.5) set
→ Door opens, motor blocked

---

🔒 Safety Logic

Feature	Implementation
Door Interlock	door button (%M0.5) blocks motor rungs while door is open
Direction Interlock	motor up (%Q0.3) and motor down (%Q0.4) are mutually exclusive
Floor Position Tracking	Memory bits ground floor sw, first floor sw, second floor sw prevent re-triggering
Travel Timers	upward lift timer and downward lift timer limit motor run time per journey

---

📚 Learning Outcomes

• PLC programming with Ladder Diagram (IEC 61131-3)
• Siemens TIA Portal V20 project structure and tag configuration
• Memory bit usage for internal state tracking
• TON timer sequencing for door and travel control
• Direction flag logic for multi-floor routing
• Motor direction control with mutual interlocking
• Live tag monitoring via TIA Portal Watch Table
• Safety interlock design in industrial ladder logic

---

🚀 Future Improvements

• Expand to 4+ floors
• HMI screen design in TIA Portal for live floor visualization
• Priority queue for multiple simultaneous floor calls
• Inside cabin call buttons separate from floor buttons
• Door obstruction detection with auto re-open
• Energy-saving idle mode
• Deploy on physical S7-1200 hardware

---

👤 Author

Mayank Jain
IoT, Robotics and Automation Enthusiast

---

📄 License

This project is shared for educational and learning purposes.