Intermediate15 min readIndustrial Manufacturing

Schneider Electric Sequential Function Charts (SFC) for Motor Control

Learn Sequential Function Charts (SFC) programming for Motor Control using Schneider Electric EcoStruxure Machine Expert. Includes code examples, best practices, and step-by-step implementation guide for Industrial Manufacturing applications.

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Platform
EcoStruxure Machine Expert
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Complexity
Beginner to Intermediate
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Project Duration
1-3 weeks
Implementing Sequential Function Charts (SFC) for Motor Control using Schneider Electric EcoStruxure Machine Expert requires adherence to industry standards and proven best practices from Industrial Manufacturing. This guide compiles best practices from successful Motor Control deployments, Schneider Electric programming standards, and Industrial Manufacturing requirements to help you deliver professional-grade automation solutions. Schneider Electric's position as High - Strong in food & beverage, water treatment, and building automation means their platforms must meet rigorous industry requirements. Companies like Modicon M580 users in pump motors and fan systems have established proven patterns for Sequential Function Charts (SFC) implementation that balance functionality, maintainability, and safety. Best practices for Motor Control encompass multiple dimensions: proper handling of 5 sensor types, safe control of 5 different actuators, managing soft start implementation, and ensuring compliance with relevant industry standards. The Sequential Function Charts (SFC) approach, when properly implemented, provides perfect for sequential processes and clear visualization of process flow, both critical for beginner to intermediate projects. This guide presents industry-validated approaches to Schneider Electric Sequential Function Charts (SFC) programming for Motor Control, covering code organization standards, documentation requirements, testing procedures, and maintenance best practices. You'll learn how leading companies structure their Motor Control programs, handle error conditions, and ensure long-term reliability in production environments.

Schneider Electric EcoStruxure Machine Expert for Motor Control

EcoStruxure Machine Expert (formerly SoMachine) provides Schneider Electric's unified programming environment for Modicon M221, M241, M251, M262, and M580 PLCs. Built on the CODESYS V3 platform, Machine Expert delivers IEC 61131-3 compliant programming with all five languages plus CFC (Continuous Function Chart). The environment supports object-oriented programming extensions including classes, interfaces, methods, and properties for creating sophisticated reusable code libraries....

Platform Strengths for Motor Control:

  • Excellent energy efficiency features

  • Strong IoT/cloud integration

  • Good balance of price and performance

  • Wide product range


Unique ${brand.software} Features:

  • CODESYS V3-based platform with full IEC 61131-3 language support plus extensions

  • Object-oriented programming with classes, methods, properties, and interfaces

  • Integrated motion control workbench for cam design and multi-axis coordination

  • Machine Expert Twin for digital twin simulation and virtual commissioning


Key Capabilities:

The EcoStruxure Machine Expert environment excels at Motor Control applications through its excellent energy efficiency features. This is particularly valuable when working with the 5 sensor types typically found in Motor Control systems, including Current sensors, Vibration sensors, Temperature sensors.

Control Equipment for Motor Control:

  • Motor control centers (MCCs)

  • AC induction motors (NEMA/IEC frame)

  • Synchronous motors for high efficiency

  • DC motors for precise speed control


Schneider Electric's controller families for Motor Control include:

  • Modicon M580: Suitable for beginner to intermediate Motor Control applications

  • Modicon M340: Suitable for beginner to intermediate Motor Control applications

  • Modicon M221: Suitable for beginner to intermediate Motor Control applications

  • Modicon M241: Suitable for beginner to intermediate Motor Control applications

Hardware Selection Guidance:

Schneider's Modicon portfolio spans compact to high-performance controllers. M221 offers cost-effective control for simple machines. M241/M251 add performance and networking. M262 targets high-performance motion applications with Sercos III. M580 addresses process applications with hot-standby redundancy....

Industry Recognition:

High - Strong in food & beverage, water treatment, and building automation. Schneider M580/M262 controllers serve automotive with production line flexibility and energy management. Vision-guided robotics, energy monitoring via PowerLogic meters, and safety integration via Preventa controllers....

Investment Considerations:

With $$ pricing, Schneider Electric positions itself in the mid-range segment. For Motor Control projects requiring beginner skill levels and 1-3 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.

Understanding Sequential Function Charts (SFC) for Motor Control

Sequential Function Chart (SFC) is a graphical language for programming sequential processes. It models systems as a series of steps connected by transitions, ideal for batch processes and machine sequences.

Execution Model:

Only active steps execute their actions. Transitions define conditions for moving between steps. Multiple steps can be active simultaneously in parallel branches.

Core Advantages for Motor Control:

  • Perfect for sequential processes: Critical for Motor Control when handling beginner to intermediate control logic

  • Clear visualization of process flow: Critical for Motor Control when handling beginner to intermediate control logic

  • Easy to understand process steps: Critical for Motor Control when handling beginner to intermediate control logic

  • Good for batch operations: Critical for Motor Control when handling beginner to intermediate control logic

  • Simplifies complex sequences: Critical for Motor Control when handling beginner to intermediate control logic


Why Sequential Function Charts (SFC) Fits Motor Control:

Motor Control systems in Industrial Manufacturing typically involve:

  • Sensors: Current transformers for motor current monitoring, RTD or thermocouple for motor winding temperature, Vibration sensors for bearing monitoring

  • Actuators: Contactors for direct-on-line starting, Soft starters for reduced voltage starting, Variable frequency drives for speed control

  • Complexity: Beginner to Intermediate with challenges including Managing starting current within supply limits


Programming Fundamentals in Sequential Function Charts (SFC):

Steps:
- initialStep: Double-bordered box - starting point of sequence, active on program start
- normalStep: Single-bordered box - becomes active when preceding transition fires
- actions: Associated code that executes while step is active

Transitions:
- condition: Boolean expression that must be TRUE to advance
- firing: Transition fires when preceding step is active AND condition is TRUE
- priority: In selective branches, transitions are evaluated in defined order

ActionQualifiers:
- N: Non-stored - executes while step is active
- S: Set - sets output TRUE on step entry, remains TRUE
- R: Reset - sets output FALSE on step entry

Best Practices for Sequential Function Charts (SFC):

  • Start with a clear process flow diagram before implementing SFC

  • Use descriptive step names indicating what happens (e.g., Filling, Heating)

  • Keep transition conditions simple - complex logic goes in action code

  • Implement timeout transitions to prevent stuck sequences

  • Always provide a path back to initial step for reset/restart


Common Mistakes to Avoid:

  • Forgetting to include stop/abort transitions for emergency handling

  • Creating deadlocks where no transition can fire

  • Not handling the case where transition conditions never become TRUE

  • Using S (Set) actions without corresponding R (Reset) actions


Typical Applications:

1. Bottle filling: Directly applicable to Motor Control
2. Assembly sequences: Related control patterns
3. Material handling: Related control patterns
4. Batch mixing: Related control patterns

Understanding these fundamentals prepares you to implement effective Sequential Function Charts (SFC) solutions for Motor Control using Schneider Electric EcoStruxure Machine Expert.

Implementing Motor Control with Sequential Function Charts (SFC)

Motor control systems use PLCs to start, stop, and regulate electric motors in industrial applications. These systems provide protection, speed control, and coordination for motors ranging from fractional horsepower to thousands of horsepower.

This walkthrough demonstrates practical implementation using Schneider Electric EcoStruxure Machine Expert and Sequential Function Charts (SFC) programming.

System Requirements:

A typical Motor Control implementation includes:

Input Devices (Sensors):
1. Current transformers for motor current monitoring: Critical for monitoring system state
2. RTD or thermocouple for motor winding temperature: Critical for monitoring system state
3. Vibration sensors for bearing monitoring: Critical for monitoring system state
4. Speed encoders or tachometers: Critical for monitoring system state
5. Torque sensors for load monitoring: Critical for monitoring system state

Output Devices (Actuators):
1. Contactors for direct-on-line starting: Primary control output
2. Soft starters for reduced voltage starting: Supporting control function
3. Variable frequency drives for speed control: Supporting control function
4. Brakes (mechanical or dynamic): Supporting control function
5. Starters (star-delta, autotransformer): Supporting control function

Control Equipment:

  • Motor control centers (MCCs)

  • AC induction motors (NEMA/IEC frame)

  • Synchronous motors for high efficiency

  • DC motors for precise speed control


Control Strategies for Motor Control:

1. Primary Control: Industrial motor control using PLCs for start/stop, speed control, and protection of electric motors.
2. Safety Interlocks: Preventing Soft start implementation
3. Error Recovery: Handling Overload protection

Implementation Steps:

Step 1: Calculate motor starting current and verify supply capacity

In EcoStruxure Machine Expert, calculate motor starting current and verify supply capacity.

Step 2: Select starting method based on motor size and load requirements

In EcoStruxure Machine Expert, select starting method based on motor size and load requirements.

Step 3: Configure motor protection with correct thermal curve

In EcoStruxure Machine Expert, configure motor protection with correct thermal curve.

Step 4: Implement control logic for start/stop with proper interlocks

In EcoStruxure Machine Expert, implement control logic for start/stop with proper interlocks.

Step 5: Add speed control loop if VFD is used

In EcoStruxure Machine Expert, add speed control loop if vfd is used.

Step 6: Configure acceleration and deceleration ramps

In EcoStruxure Machine Expert, configure acceleration and deceleration ramps.


Schneider Electric Function Design:

Function blocks follow object-oriented principles with Input/Output/InOut parameters, Methods extending functionality, and Properties providing controlled access. Interfaces enable polymorphism.

Common Challenges and Solutions:

1. Managing starting current within supply limits

  • Solution: Sequential Function Charts (SFC) addresses this through Perfect for sequential processes.


2. Coordinating acceleration with driven load requirements

  • Solution: Sequential Function Charts (SFC) addresses this through Clear visualization of process flow.


3. Protecting motors from frequent starting (thermal cycling)

  • Solution: Sequential Function Charts (SFC) addresses this through Easy to understand process steps.


4. Handling regenerative energy during deceleration

  • Solution: Sequential Function Charts (SFC) addresses this through Good for batch operations.


Safety Considerations:

  • Proper machine guarding for rotating equipment

  • Emergency stop functionality with safe torque off

  • Lockout/tagout provisions for maintenance

  • Arc flash protection and PPE requirements

  • Proper grounding and bonding


Performance Metrics:

  • Scan Time: Optimize for 5 inputs and 5 outputs

  • Memory Usage: Efficient data structures for Modicon M580 capabilities

  • Response Time: Meeting Industrial Manufacturing requirements for Motor Control

Schneider Electric Diagnostic Tools:

Online monitoring overlay showing live values,Watch window tracking variables with expressions,Breakpoints pausing execution for inspection,Trace recording variable changes over time,Device diagnostics showing module status

Schneider Electric's EcoStruxure Machine Expert provides tools for performance monitoring and optimization, essential for achieving the 1-3 weeks development timeline while maintaining code quality.

Schneider Electric Sequential Function Charts (SFC) Example for Motor Control

Complete working example demonstrating Sequential Function Charts (SFC) implementation for Motor Control using Schneider Electric EcoStruxure Machine Expert. Follows Schneider Electric naming conventions. Tested on Modicon M580 hardware.

// Schneider Electric EcoStruxure Machine Expert - Motor Control Control
// Sequential Function Charts (SFC) Implementation for Industrial Manufacturing
// Schneider recommends Hungarian-style prefixes: g_ for global

// ============================================
// Variable Declarations
// ============================================
VAR
    bEnable : BOOL := FALSE;
    bEmergencyStop : BOOL := FALSE;
    rCurrentsensors : REAL;
    rMotorstarters : REAL;
END_VAR

// ============================================
// Input Conditioning - Current transformers for motor current monitoring
// ============================================
// Standard input processing
IF rCurrentsensors > 0.0 THEN
    bEnable := TRUE;
END_IF;

// ============================================
// Safety Interlock - Proper machine guarding for rotating equipment
// ============================================
IF bEmergencyStop THEN
    rMotorstarters := 0.0;
    bEnable := FALSE;
END_IF;

// ============================================
// Main Motor Control Control Logic
// ============================================
IF bEnable AND NOT bEmergencyStop THEN
    // Motor control systems use PLCs to start, stop, and regulate 
    rMotorstarters := rCurrentsensors * 1.0;

    // Process monitoring
    // Add specific control logic here
ELSE
    rMotorstarters := 0.0;
END_IF;

Code Explanation:

  • 1.Sequential Function Charts (SFC) structure optimized for Motor Control in Industrial Manufacturing applications
  • 2.Input conditioning handles Current transformers for motor current monitoring signals
  • 3.Safety interlock ensures Proper machine guarding for rotating equipment always takes priority
  • 4.Main control implements Motor control systems use PLCs to start,
  • 5.Code runs every scan cycle on Modicon M580 (typically 5-20ms)

Best Practices

  • Follow Schneider Electric naming conventions: Schneider recommends Hungarian-style prefixes: g_ for globals, i_ and q_ for FB
  • Schneider Electric function design: Function blocks follow object-oriented principles with Input/Output/InOut parame
  • Data organization: Structured data uses GVLs grouping related globals and DUTs defining custom type
  • Sequential Function Charts (SFC): Start with a clear process flow diagram before implementing SFC
  • Sequential Function Charts (SFC): Use descriptive step names indicating what happens (e.g., Filling, Heating)
  • Sequential Function Charts (SFC): Keep transition conditions simple - complex logic goes in action code
  • Motor Control: Verify motor running with current or speed feedback, not just contactor status
  • Motor Control: Implement minimum off time between starts for motor cooling
  • Motor Control: Add phase loss and phase reversal protection
  • Debug with EcoStruxure Machine Expert: Use structured logging with severity levels
  • Safety: Proper machine guarding for rotating equipment
  • Use EcoStruxure Machine Expert simulation tools to test Motor Control logic before deployment

Common Pitfalls to Avoid

  • Sequential Function Charts (SFC): Forgetting to include stop/abort transitions for emergency handling
  • Sequential Function Charts (SFC): Creating deadlocks where no transition can fire
  • Sequential Function Charts (SFC): Not handling the case where transition conditions never become TRUE
  • Schneider Electric common error: Exception 'AccessViolation': Null pointer dereference
  • Motor Control: Managing starting current within supply limits
  • Motor Control: Coordinating acceleration with driven load requirements
  • Neglecting to validate Current transformers for motor current monitoring leads to control errors
  • Insufficient comments make Sequential Function Charts (SFC) programs unmaintainable over time

Related Certifications

🏆EcoStruxure Certified Expert
Mastering Sequential Function Charts (SFC) for Motor Control applications using Schneider Electric EcoStruxure Machine Expert requires understanding both the platform's capabilities and the specific demands of Industrial Manufacturing. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with beginner to intermediate Motor Control projects. Schneider Electric's 12% market share and high - strong in food & beverage, water treatment, and building automation demonstrate the platform's capability for demanding applications. The platform excels in Industrial Manufacturing applications where Motor Control reliability is critical. By following the practices outlined in this guide—from proper program structure and Sequential Function Charts (SFC) best practices to Schneider Electric-specific optimizations—you can deliver reliable Motor Control systems that meet Industrial Manufacturing requirements. **Next Steps for Professional Development:** 1. **Certification**: Pursue EcoStruxure Certified Expert to validate your Schneider Electric expertise 3. **Hands-on Practice**: Build Motor Control projects using Modicon M580 hardware 4. **Stay Current**: Follow EcoStruxure Machine Expert updates and new Sequential Function Charts (SFC) features **Sequential Function Charts (SFC) Foundation:** Sequential Function Chart (SFC) is a graphical language for programming sequential processes. It models systems as a series of steps connected by tran... The 1-3 weeks typical timeline for Motor Control projects will decrease as you gain experience with these patterns and techniques. Remember: Verify motor running with current or speed feedback, not just contactor status For further learning, explore related topics including Assembly sequences, Fan systems, and Schneider Electric platform-specific features for Motor Control optimization.