Diagrama de Escalera Simulación del Silo en LogixPro

Key Concepts

• PLC (Programmable Logic Controller) programming
• Ladder logic
• Silo simulation
• Inputs and outputs (I/O)
• Sensors (proximity, level)
• Actuators (solenoid valve, conveyor motor)
• Memory bits
• Interlocks
• Start/Stop circuits
• Simulation and testing

Silo Simulation Explanation

Introduction

The video explains the solution to a silo simulation exercise using ladder logic in a PLC. The solution was provided by Gonzalo Romero, and the video aims to explain the logic behind the program. The presenter emphasizes the importance of breaking down the process into fundamental steps and using memory bits to control the sequence.

Problem Definition

The silo simulation involves the following steps:

1. Start the conveyor belt.
2. Detect a box using a proximity sensor.
3. Activate a solenoid valve to fill the box with material.
4. Detect the material level using a level sensor.
5. Deactivate the solenoid valve.
6. Continue the conveyor belt to move the filled box.
7. Repeat the process.
8. Indicate the running, filling, and full states using indicator lamps.
9. Use selector switches (A, B, and C) for different operating modes.

Programming Methodology

The presenter outlines a structured approach to PLC programming:

1. Understand the Process: Clearly define the steps involved in the machine's operation.
2. Divide into Fundamental Steps: Break down the process into general steps (e.g., start conveyor, stop conveyor, activate solenoid, deactivate solenoid).
3. Subdivide into Memory Bits: Use memory bits to represent the state of each step. This allows for better control and avoids errors.
4. Implement Ladder Logic: Translate the steps and memory bits into ladder logic rungs.

Ladder Logic Implementation

Rung 000: Start/Stop Circuit for Run Lamp

• Purpose: To control the "Run" lamp, indicating that the system is active.
• Components:
  • Normally open contact: I:2.1/1 (Stop button) - labeled "Stop"
  • Normally open contact: I:2.1/0 (Start button) - labeled "Start"
  • Output coil: O:2.2/2 (Run lamp) - labeled "Run"
  • Normally open contact: O:2.2/2 (Run lamp) - for latching/seal-in circuit
• Logic:
  • The Stop button is a normally closed physical contact, so it appears as normally open in the ladder logic.
  • Pressing the Start button energizes the Run lamp output.
  • The Run lamp contact latches the circuit, keeping the Run lamp on even after the Start button is released.
  • Pressing the Stop button de-energizes the Run lamp, stopping the system.
• Explanation: The presenter emphasizes that the Stop button is wired as normally closed in the field, so it appears as normally open in the PLC program. This ensures that the circuit is broken when the Stop button is pressed.

Rung 001: Motor Control

• Purpose: To control the conveyor motor.
• Components:
  • Normally open contact: O:2.2/2 (Run lamp) - "Run" memory bit
  • Normally closed contact: I:2.1/3 (Proximity sensor) - "Prox Sensor"
  • Output coil: O:2.2/0 (Motor) - labeled "Motor"
• Logic:
  • The motor can only run if the Run lamp is on (system is started).
  • The motor stops when the proximity sensor detects a box (the contact opens).
• Explanation: The Run lamp acts as a memory bit, ensuring that the motor only runs when the system is active. The proximity sensor is wired as normally open in the field, so it appears as normally closed in the ladder logic. This ensures that the motor stops when a box is detected.

Rung 002: Solenoid Valve Control

• Purpose: To control the solenoid valve, filling the box with material.
• Components:
  • Normally open contact: O:2.2/2 (Run lamp) - "Run" memory bit
  • Normally open contact: I:2.1/3 (Proximity sensor) - "Prox Sensor"
  • Normally closed contact: O:2.2/0 (Motor) - "Motor"
  • Output coil: O:2.2/1 (Solenoid valve) - labeled "Solenoid Valve"
  • Output coil: O:2.2/3 (Fill lamp) - labeled "Fill"
• Logic:
  • The solenoid valve can only activate if the Run lamp is on, the proximity sensor detects a box, and the motor is not running.
  • The Fill lamp is activated simultaneously with the solenoid valve.
• Explanation: The motor contact is used as an interlock, ensuring that the solenoid valve only activates when the conveyor belt is stopped. The Fill lamp provides visual feedback that the box is being filled.

Rung 003: Full Sensor and Latching

• Purpose: To detect when the box is full and latch the "Full" state.
• Components:
  • Normally open contact: I:2.1/4 (Level sensor) - "Nivel Sensor"
  • Normally open contact: I:2.1/3 (Proximity sensor) - "Prox Sensor"
  • Output coil: O:2.2/4 (Full) - labeled "Full"
  • Normally open contact: O:2.2/4 (Full) - for latching/seal-in circuit
• Logic:
  • The "Full" output is energized when the level sensor detects a full box and the proximity sensor is active.
  • The "Full" contact latches the circuit, keeping the "Full" output on even after the level sensor is no longer active.

Rung 004: Solenoid Valve Shutoff

• Purpose: To shut off the solenoid valve when the box is full.
• Components:
  • Normally closed contact: O:2.2/4 (Full) - "Full"
• Logic:
  • When the "Full" output is energized, this contact opens, de-energizing the solenoid valve.

Rung 005: Restarting the Conveyor

• Purpose: To restart the conveyor after the box is full.
• Components:
  • Normally open contact: O:2.2/4 (Full) - "Full"
• Logic:
  • When the "Full" output is energized, this contact closes, energizing the motor.

Rung 006: Switch A

• Purpose: To enable the program to run when switch A is selected.
• Components:
  • Normally open contact: I:2.1/5 (Switch A) - "a"
• Logic:
  • The program will only run if switch A is selected.

Simulation and Testing

The presenter demonstrates the simulation of the ladder logic program using LogixPro. The simulation shows the following:

• The conveyor belt starts when the Start button is pressed.
• The conveyor belt stops when a box is detected by the proximity sensor.
• The solenoid valve activates, filling the box with material.
• The solenoid valve deactivates when the level sensor detects a full box.
• The conveyor belt restarts, moving the filled box.
• The Run, Fill, and Full lamps indicate the system's state.

Key Arguments and Perspectives

• Importance of Memory Bits: The presenter emphasizes the importance of using memory bits to represent the state of each step in the process. This allows for better control and avoids errors.
• Structured Programming: The presenter advocates for a structured approach to PLC programming, breaking down the process into fundamental steps and using memory bits to control the sequence.
• Avoiding "All-in-One" Rungs: The presenter advises against combining multiple functions into a single rung, as this can make the program difficult to understand and maintain.
• Understanding Physical Wiring: The presenter stresses the importance of understanding the physical wiring of input devices (e.g., normally closed stop buttons) and how they translate into ladder logic.

Conclusion

The video provides a detailed explanation of a silo simulation solution using ladder logic. The presenter emphasizes the importance of structured programming, memory bits, and understanding the physical wiring of input devices. The simulation demonstrates the correct operation of the ladder logic program. The presenter encourages viewers to practice similar exercises to improve their PLC programming skills.