Learning to implement Sequential Function Charts (SFC) for Material Handling using INVT's INVT Workshop / AutoStudio is an essential skill for PLC programmers working in Logistics & Warehousing. This comprehensive guide walks you through the fundamentals, providing clear explanations and practical examples that you can apply immediately to real-world projects.
INVT has established itself as Moderate in HVAC, water treatment, textiles, basic process equipment, and OEM machines paired with INVT drives, making it a strategic choice for Material Handling applications. With <1% global global market share and 5 popular PLC families including the IVC1 and IVC2, INVT provides the robust platform needed for intermediate to advanced complexity projects like Material Handling.
The Sequential Function Charts (SFC) approach is particularly well-suited for Material Handling because batch processes, step-by-step operations, state machines, and complex sequential control. This combination allows you to leverage perfect for sequential processes while managing the typical challenges of Material Handling, including route optimization and traffic management.
Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on INVT Workshop / AutoStudio, and industry best practices specific to Logistics & Warehousing. Whether you're programming your first Material Handling system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with INVT Sequential Function Charts (SFC) programming.
INVT INVT Workshop / AutoStudio for Material Handling
INVT Workshop and AutoStudio are the two programming tools for the IVC-series PLCs (IVC1, IVC2, IVC3) and the AX-series (AX70 etc.) respectively. The core IDE feel is FX-style — ladder, IL, and SFC editors with soft-element tables and offline simulator support — and the instruction set borrows from Mitsubishi FX conventions. INVT's heritage is in drives (variable-frequency and servo) rather than PLCs, and the engineering tools reflect that bias: drive-PLC integration is unusually clean, with a u...
Platform Strengths for Material Handling:
- Excellent price-performance for combined PLC + drive systems
- Free programming software with simulator
- Compact CPUs with built-in pulse outputs and PID
- Strong drives heritage — tight VFD/servo integration
Unique ${brand.software} Features:
- Free Workshop / AutoStudio IDE with offline simulator
- FX-style instruction set easing migration
- Tight integration with INVT VFDs and servo drives
- Unified scope / trace across PLC and drive parameters
Key Capabilities:
The INVT Workshop / AutoStudio environment excels at Material Handling applications through its excellent price-performance for combined plc + drive systems. This is particularly valuable when working with the 5 sensor types typically found in Material Handling systems, including Laser scanners, RFID readers, Barcode scanners.
Control Equipment for Material Handling:
- Automated storage and retrieval systems (AS/RS)
- Automated guided vehicles (AGVs/AMRs)
- Vertical lift modules (VLMs)
- Carousel systems (horizontal and vertical)
INVT's controller families for Material Handling include:
- IVC1: Suitable for intermediate to advanced Material Handling applications
- IVC2: Suitable for intermediate to advanced Material Handling applications
- IVC3: Suitable for intermediate to advanced Material Handling applications
- AX series: Suitable for intermediate to advanced Material Handling applications
Hardware Selection Guidance:
IVC1 covers entry compact applications, IVC2 / IVC3 are mid-range with extended I/O and Ethernet (IVC3-Ethernet variants), AX70 represents INVT's higher-tier compact-modular line with motion features. Choice usually mirrors the drive size — small VFDs pair with IVC1; AX70 fits where servo motion and EtherCAT-like buses are required....
Industry Recognition:
Moderate in HVAC, water treatment, textiles, basic process equipment, and OEM machines paired with INVT drives. Limited Tier 1 presence; common in Chinese aftermarket fixturing where INVT VFDs are already specified....
Investment Considerations:
With $ pricing, INVT positions itself in the value segment. For Material Handling projects requiring advanced skill levels and 4-12 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.
Understanding Sequential Function Charts (SFC) for Material Handling
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 Material Handling:
- Perfect for sequential processes: Critical for Material Handling when handling intermediate to advanced control logic
- Clear visualization of process flow: Critical for Material Handling when handling intermediate to advanced control logic
- Easy to understand process steps: Critical for Material Handling when handling intermediate to advanced control logic
- Good for batch operations: Critical for Material Handling when handling intermediate to advanced control logic
- Simplifies complex sequences: Critical for Material Handling when handling intermediate to advanced control logic
Why Sequential Function Charts (SFC) Fits Material Handling:
Material Handling systems in Logistics & Warehousing typically involve:
- Sensors: Barcode scanners for product/location identification, RFID readers for pallet and container tracking, Photoelectric sensors for load presence detection
- Actuators: Conveyor motors and drives, Crane bridge, hoist, and trolley drives, Shuttle car drives
- Complexity: Intermediate to Advanced with challenges including Maintaining inventory accuracy in real-time
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 Material Handling
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 Material Handling using INVT INVT Workshop / AutoStudio.
Implementing Material Handling with Sequential Function Charts (SFC)
Material handling automation uses PLCs to control the movement, storage, and retrieval of materials in warehouses, distribution centers, and manufacturing facilities. These systems optimize storage density, picking efficiency, and inventory accuracy.
This walkthrough demonstrates practical implementation using INVT INVT Workshop / AutoStudio and Sequential Function Charts (SFC) programming.
System Requirements:
A typical Material Handling implementation includes:
Input Devices (Sensors):
1. Barcode scanners for product/location identification: Critical for monitoring system state
2. RFID readers for pallet and container tracking: Critical for monitoring system state
3. Photoelectric sensors for load presence detection: Critical for monitoring system state
4. Height and dimension sensors for load verification: Critical for monitoring system state
5. Position encoders for crane and shuttle systems: Critical for monitoring system state
Output Devices (Actuators):
1. Conveyor motors and drives: Primary control output
2. Crane bridge, hoist, and trolley drives: Supporting control function
3. Shuttle car drives: Supporting control function
4. Fork positioning and load handling: Supporting control function
5. Vertical lift mechanisms: Supporting control function
Control Equipment:
- Automated storage and retrieval systems (AS/RS)
- Automated guided vehicles (AGVs/AMRs)
- Vertical lift modules (VLMs)
- Carousel systems (horizontal and vertical)
Control Strategies for Material Handling:
1. Primary Control: Automated material movement using PLCs for warehouse automation, AGVs, and logistics systems.
2. Safety Interlocks: Preventing Route optimization
3. Error Recovery: Handling Traffic management
Implementation Steps:
Step 1: Map all storage locations with addressing scheme
In INVT Workshop / AutoStudio, map all storage locations with addressing scheme.
Step 2: Define product characteristics (size, weight, handling requirements)
In INVT Workshop / AutoStudio, define product characteristics (size, weight, handling requirements).
Step 3: Implement location tracking database interface
In INVT Workshop / AutoStudio, implement location tracking database interface.
Step 4: Program crane/shuttle motion control with positioning
In INVT Workshop / AutoStudio, program crane/shuttle motion control with positioning.
Step 5: Add load verification (presence, dimension, weight)
In INVT Workshop / AutoStudio, add load verification (presence, dimension, weight).
Step 6: Implement WMS interface for task assignment
In INVT Workshop / AutoStudio, implement wms interface for task assignment.
INVT Function Design:
P-label subroutines plus a small library of INVT-supplied drive-control FBs that wrap the proprietary Modbus parameter map. Reuse beyond the supplied library is open-coded.
Common Challenges and Solutions:
1. Maintaining inventory accuracy in real-time
- Solution: Sequential Function Charts (SFC) addresses this through Perfect for sequential processes.
2. Handling damaged or misplaced loads
- Solution: Sequential Function Charts (SFC) addresses this through Clear visualization of process flow.
3. Coordinating multiple cranes in same aisle
- Solution: Sequential Function Charts (SFC) addresses this through Easy to understand process steps.
4. Optimizing storage assignment dynamically
- Solution: Sequential Function Charts (SFC) addresses this through Good for batch operations.
Safety Considerations:
- Aisle entry protection with light curtains and interlocks
- Personnel detection in automated zones
- Safe positioning for maintenance access
- Overload protection for cranes and lifts
- Fire suppression system integration
Performance Metrics:
- Scan Time: Optimize for 5 inputs and 5 outputs
- Memory Usage: Efficient data structures for IVC1 capabilities
- Response Time: Meeting Logistics & Warehousing requirements for Material Handling
INVT Diagnostic Tools:
Workshop online monitoring with rung-state highlighting,Combined PLC + drive scope / trace tool,Soft-element watch table,Drive-parameter live-monitor view,Modbus RTU / TCP communication analyzer,Built-in offline simulator,Distributor loaner CPU/drive pairs for triage,INVT community forum (Chinese-dominant) for protocol-specific issues
INVT's INVT Workshop / AutoStudio provides tools for performance monitoring and optimization, essential for achieving the 4-12 weeks development timeline while maintaining code quality.
INVT Sequential Function Charts (SFC) Example for Material Handling
Complete working example demonstrating Sequential Function Charts (SFC) implementation for Material Handling using INVT INVT Workshop / AutoStudio. Follows INVT naming conventions. Tested on IVC1 hardware.
// INVT INVT Workshop / AutoStudio - Material Handling Control
// Sequential Function Charts (SFC) Implementation for Logistics & Warehousing
// Raw FX-style addressing dominates. Symbolic naming is suppor
// ============================================
// Variable Declarations
// ============================================
VAR
bEnable : BOOL := FALSE;
bEmergencyStop : BOOL := FALSE;
rLaserscanners : REAL;
rAGVmotors : REAL;
END_VAR
// ============================================
// Input Conditioning - Barcode scanners for product/location identification
// ============================================
// Standard input processing
IF rLaserscanners > 0.0 THEN
bEnable := TRUE;
END_IF;
// ============================================
// Safety Interlock - Aisle entry protection with light curtains and interlocks
// ============================================
IF bEmergencyStop THEN
rAGVmotors := 0.0;
bEnable := FALSE;
END_IF;
// ============================================
// Main Material Handling Control Logic
// ============================================
IF bEnable AND NOT bEmergencyStop THEN
// Material handling automation uses PLCs to control the moveme
rAGVmotors := rLaserscanners * 1.0;
// Process monitoring
// Add specific control logic here
ELSE
rAGVmotors := 0.0;
END_IF;Code Explanation:
- 1.Sequential Function Charts (SFC) structure optimized for Material Handling in Logistics & Warehousing applications
- 2.Input conditioning handles Barcode scanners for product/location identification signals
- 3.Safety interlock ensures Aisle entry protection with light curtains and interlocks always takes priority
- 4.Main control implements Material handling automation uses PLCs t
- 5.Code runs every scan cycle on IVC1 (typically 5-20ms)
Best Practices
- ✓Follow INVT naming conventions: Raw FX-style addressing dominates. Symbolic naming is supported but rarely used
- ✓INVT function design: P-label subroutines plus a small library of INVT-supplied drive-control FBs that
- ✓Data organization: No structured DB; D / HD register banks with engineer-documented range conventio
- ✓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
- ✓Material Handling: Verify load presence before and after each move
- ✓Material Handling: Implement inventory checkpoints for reconciliation
- ✓Material Handling: Use location states to prevent double storage
- ✓Debug with INVT Workshop / AutoStudio: Use the combined scope to confirm whether a fault is in PLC logic or i
- ✓Safety: Aisle entry protection with light curtains and interlocks
- ✓Use INVT Workshop / AutoStudio simulation tools to test Material Handling 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
- ⚠INVT common error: Drive-parameter mapping desync after firmware update on attached VFD
- ⚠Material Handling: Maintaining inventory accuracy in real-time
- ⚠Material Handling: Handling damaged or misplaced loads
- ⚠Neglecting to validate Barcode scanners for product/location identification leads to control errors
- ⚠Insufficient comments make Sequential Function Charts (SFC) programs unmaintainable over time
Related Certifications
Mastering Sequential Function Charts (SFC) for Material Handling applications using INVT INVT Workshop / AutoStudio requires understanding both the platform's capabilities and the specific demands of Logistics & Warehousing. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with intermediate to advanced Material Handling projects.
INVT's <1% global market share and moderate in hvac, water treatment, textiles, basic process equipment, and oem machines paired with invt drives demonstrate the platform's capability for demanding applications. The platform excels in Logistics & Warehousing applications where Material Handling reliability is critical.
By following the practices outlined in this guide—from proper program structure and Sequential Function Charts (SFC) best practices to INVT-specific optimizations—you can deliver reliable Material Handling systems that meet Logistics & Warehousing requirements.
Next Steps for Professional Development:
1. Certification: Pursue INVT distributor training to validate your INVT expertise
2. Advanced Training: Consider Drive-PLC integration certificates for specialized Logistics & Warehousing applications
3. Hands-on Practice: Build Material Handling projects using IVC1 hardware
4. Stay Current: Follow INVT Workshop / AutoStudio 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 4-12 weeks typical timeline for Material Handling projects will decrease as you gain experience with these patterns and techniques. Remember: Verify load presence before and after each move
For further learning, explore related topics including Assembly sequences, AGV systems, and INVT platform-specific features for Material Handling optimization.