Learning to implement Sequential Function Charts (SFC) for Bottle Filling using Unitronics's VisiLogic / UniLogic is an essential skill for PLC programmers working in Packaging. This comprehensive guide walks you through the fundamentals, providing clear explanations and practical examples that you can apply immediately to real-world projects.
Unitronics has established itself as Moderate - US small-integrator market, OEM machines, building automation, making it a strategic choice for Bottle Filling applications. With 1% global market share and 6 popular PLC families including the Jazz 2 and Samba 7", Unitronics provides the robust platform needed for intermediate to advanced complexity projects like Bottle Filling.
The Sequential Function Charts (SFC) approach is particularly well-suited for Bottle Filling 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 Bottle Filling, including precise fill volume and high-speed operation.
Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on VisiLogic / UniLogic, and industry best practices specific to Packaging. Whether you're programming your first Bottle Filling system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with Unitronics Sequential Function Charts (SFC) programming.
Unitronics VisiLogic / UniLogic for Bottle Filling
Unitronics takes a distinctive approach to PLC programming: every controller ships with an integrated colour touchscreen HMI, and the development tool handles PLC logic and HMI design in a single workspace. VisiLogic is the legacy tool for the Vision, Samba, and Jazz product families; UniLogic is the current-generation environment for the UniStream line. Both are free to download and include a complete built-in simulator covering PLC logic, HMI screens, alarms, recipes, and data tables — the sim...
Platform Strengths for Bottle Filling:
- Combined PLC + HMI in one unit reduces panel cost
- Free VisiLogic and UniLogic IDEs
- Built-in simulator with both PLC and HMI simulation
- Strong US small-integrator community
Unique ${brand.software} Features:
- Combined PLC + HMI in one unit across Jazz, Samba, Vision, and UniStream
- Free VisiLogic (legacy) and UniLogic (current) IDEs
- Built-in simulator covering PLC logic, HMI, alarms, data tables, and recipes
- Integrated data sampling and trend logging without separate SCADA
Key Capabilities:
The VisiLogic / UniLogic environment excels at Bottle Filling applications through its combined plc + hmi in one unit reduces panel cost. This is particularly valuable when working with the 5 sensor types typically found in Bottle Filling systems, including Level sensors, Flow meters, Pressure sensors.
Control Equipment for Bottle Filling:
- Filling nozzles (gravity, pressure, vacuum)
- Product tanks with level control
- CIP (clean-in-place) systems
- Cap feeding and sorting equipment
Unitronics's controller families for Bottle Filling include:
- Jazz 2: Suitable for intermediate to advanced Bottle Filling applications
- Samba 7": Suitable for intermediate to advanced Bottle Filling applications
- Vision V350: Suitable for intermediate to advanced Bottle Filling applications
- Vision V570: Suitable for intermediate to advanced Bottle Filling applications
Hardware Selection Guidance:
CPU selection across Unitronics ranges from the Jazz 2 micro series (tiny applications, basic motor control, simple process monitoring with 10-20 I/O) through Samba 7" (small machine control with touchscreen HMI), Vision V350/V570 (medium machinery with larger HMI), and UniStream 7" / 15.6" (flagship combined PLC+HMI for mid-to-high complexity applications with advanced features like UniCloud, cel...
Industry Recognition:
Moderate - US small-integrator market, OEM machines, building automation. Unitronics' combined PLC+HMI controllers are uncommon in high-volume automotive manufacturing but appear in automotive tier-2 and tier-3 supplier shops, single-machine workcells, and after-market test fixtures. The cost advantage and single-unit PLC+HMI approach makes Unitronics attractive for small...
Investment Considerations:
With $$ pricing, Unitronics positions itself in the mid-range segment. For Bottle Filling projects requiring advanced skill levels and 3-6 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.
Understanding Sequential Function Charts (SFC) for Bottle Filling
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 Bottle Filling:
- Perfect for sequential processes: Critical for Bottle Filling when handling intermediate to advanced control logic
- Clear visualization of process flow: Critical for Bottle Filling when handling intermediate to advanced control logic
- Easy to understand process steps: Critical for Bottle Filling when handling intermediate to advanced control logic
- Good for batch operations: Critical for Bottle Filling when handling intermediate to advanced control logic
- Simplifies complex sequences: Critical for Bottle Filling when handling intermediate to advanced control logic
Why Sequential Function Charts (SFC) Fits Bottle Filling:
Bottle Filling systems in Packaging typically involve:
- Sensors: Bottle presence sensors (fiber optic or inductive) for container detection, Level sensors (capacitive, ultrasonic, or optical) for fill detection, Load cells for gravimetric (weight-based) filling
- Actuators: Servo-driven filling valves for precise flow control, Pneumatic pinch valves for on/off flow control, Bottle handling star wheels and timing screws
- Complexity: Intermediate to Advanced with challenges including Preventing dripping and stringing after fill cutoff
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 Bottle Filling
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 Bottle Filling using Unitronics VisiLogic / UniLogic.
Implementing Bottle Filling with Sequential Function Charts (SFC)
Bottle filling control systems manage the precise dispensing of liquids into containers at high speeds while maintaining accuracy and preventing spillage. PLCs coordinate container handling, fill control, capping, and quality inspection in an integrated packaging line.
This walkthrough demonstrates practical implementation using Unitronics VisiLogic / UniLogic and Sequential Function Charts (SFC) programming.
System Requirements:
A typical Bottle Filling implementation includes:
Input Devices (Sensors):
1. Bottle presence sensors (fiber optic or inductive) for container detection: Critical for monitoring system state
2. Level sensors (capacitive, ultrasonic, or optical) for fill detection: Critical for monitoring system state
3. Load cells for gravimetric (weight-based) filling: Critical for monitoring system state
4. Flow meters (magnetic or mass flow) for volumetric filling: Critical for monitoring system state
5. Encoder feedback for rotary filler position: Critical for monitoring system state
Output Devices (Actuators):
1. Servo-driven filling valves for precise flow control: Primary control output
2. Pneumatic pinch valves for on/off flow control: Supporting control function
3. Bottle handling star wheels and timing screws: Supporting control function
4. Capping chuck drives (servo or pneumatic): Supporting control function
5. Torque limiters for cap tightening: Supporting control function
Control Equipment:
- Filling nozzles (gravity, pressure, vacuum)
- Product tanks with level control
- CIP (clean-in-place) systems
- Cap feeding and sorting equipment
Control Strategies for Bottle Filling:
1. Primary Control: Automated bottle filling and capping systems using PLCs for precise volume control, speed optimization, and quality assurance.
2. Safety Interlocks: Preventing Precise fill volume
3. Error Recovery: Handling High-speed operation
Implementation Steps:
Step 1: Characterize product flow properties (viscosity, foaming, temperature sensitivity)
In VisiLogic / UniLogic, characterize product flow properties (viscosity, foaming, temperature sensitivity).
Step 2: Determine fill method based on accuracy requirements and product type
In VisiLogic / UniLogic, determine fill method based on accuracy requirements and product type.
Step 3: Design container handling for smooth, jam-free operation
In VisiLogic / UniLogic, design container handling for smooth, jam-free operation.
Step 4: Implement fill sequence with proper valve timing and deceleration
In VisiLogic / UniLogic, implement fill sequence with proper valve timing and deceleration.
Step 5: Add bulk/dribble transition logic for gravimetric filling
In VisiLogic / UniLogic, add bulk/dribble transition logic for gravimetric filling.
Step 6: Program calibration routines for automatic fill adjustment
In VisiLogic / UniLogic, program calibration routines for automatic fill adjustment.
Unitronics Function Design:
Function block design in Unitronics uses user-defined FBs in UniLogic (more limited in VisiLogic). Extensive vendor-provided helper FBs cover common tasks (PID, motion, communication, HMI utilities). OEM machine builders typically maintain private FB libraries for their common machine patterns, though code reuse is less mature than in mainstream PLC ecosystems.
Common Challenges and Solutions:
1. Preventing dripping and stringing after fill cutoff
- Solution: Sequential Function Charts (SFC) addresses this through Perfect for sequential processes.
2. Handling foaming products that give false level readings
- Solution: Sequential Function Charts (SFC) addresses this through Clear visualization of process flow.
3. Maintaining accuracy at high speeds
- Solution: Sequential Function Charts (SFC) addresses this through Easy to understand process steps.
4. Synchronizing multi-head rotary fillers
- Solution: Sequential Function Charts (SFC) addresses this through Good for batch operations.
Safety Considerations:
- Guarding around rotating components
- Interlocked access doors with safe stop
- Bottle breakage detection and containment
- Overpressure protection for pressure filling
- Chemical handling safety for cleaning solutions
Performance Metrics:
- Scan Time: Optimize for 5 inputs and 5 outputs
- Memory Usage: Efficient data structures for Jazz 2 capabilities
- Response Time: Meeting Packaging requirements for Bottle Filling
Unitronics Diagnostic Tools:
UniLogic (current) and VisiLogic (legacy) integrated debuggers with breakpoints,Built-in simulator covering PLC logic, HMI screens, alarms, recipes, and data tables,Web visualisation for UniStream — remote HMI viewing without additional software,SD card logging with PC-side export tools for offline trend analysis,Modbus RTU/TCP transaction logging built into the IDE,Controller status monitor — CPU load, scan time, memory usage,HMI event logger capturing operator actions for audit purposes,CAN bus diagnostic tools for CANopen-equipped models,Remote support tool — Unitronics' own screen-sharing for technical support,User community forum with active troubleshooting discussions
Unitronics's VisiLogic / UniLogic provides tools for performance monitoring and optimization, essential for achieving the 3-6 weeks development timeline while maintaining code quality.
Unitronics Sequential Function Charts (SFC) Example for Bottle Filling
Complete working example demonstrating Sequential Function Charts (SFC) implementation for Bottle Filling using Unitronics VisiLogic / UniLogic. Follows Unitronics naming conventions. Tested on Jazz 2 hardware.
// Unitronics VisiLogic / UniLogic - Bottle Filling Control
// Sequential Function Charts (SFC) Implementation for Packaging
// Unitronics projects use IDE-managed tag names rather than ra
// ============================================
// Variable Declarations
// ============================================
VAR
bEnable : BOOL := FALSE;
bEmergencyStop : BOOL := FALSE;
rLevelsensors : REAL;
rServomotors : REAL;
END_VAR
// ============================================
// Input Conditioning - Bottle presence sensors (fiber optic or inductive) for container detection
// ============================================
// Standard input processing
IF rLevelsensors > 0.0 THEN
bEnable := TRUE;
END_IF;
// ============================================
// Safety Interlock - Guarding around rotating components
// ============================================
IF bEmergencyStop THEN
rServomotors := 0.0;
bEnable := FALSE;
END_IF;
// ============================================
// Main Bottle Filling Control Logic
// ============================================
IF bEnable AND NOT bEmergencyStop THEN
// Bottle filling control systems manage the precise dispensing
rServomotors := rLevelsensors * 1.0;
// Process monitoring
// Add specific control logic here
ELSE
rServomotors := 0.0;
END_IF;Code Explanation:
- 1.Sequential Function Charts (SFC) structure optimized for Bottle Filling in Packaging applications
- 2.Input conditioning handles Bottle presence sensors (fiber optic or inductive) for container detection signals
- 3.Safety interlock ensures Guarding around rotating components always takes priority
- 4.Main control implements Bottle filling control systems manage th
- 5.Code runs every scan cycle on Jazz 2 (typically 5-20ms)
Best Practices
- ✓Follow Unitronics naming conventions: Unitronics projects use IDE-managed tag names rather than raw memory addressing.
- ✓Unitronics function design: Function block design in Unitronics uses user-defined FBs in UniLogic (more limi
- ✓Data organization: Unitronics uses its own tag database concept rather than IEC-standard data block
- ✓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
- ✓Bottle Filling: Use minimum 10 readings for statistical fill tracking
- ✓Bottle Filling: Implement automatic re-zero of scales at regular intervals
- ✓Bottle Filling: Provide separate parameters for each product recipe
- ✓Debug with VisiLogic / UniLogic: Use the built-in simulator to reproduce issues before hardware visit
- ✓Safety: Guarding around rotating components
- ✓Use VisiLogic / UniLogic simulation tools to test Bottle Filling 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
- ⚠Unitronics common error: VisiLogic-to-UniLogic migration issues — not all projects convert cleanly
- ⚠Bottle Filling: Preventing dripping and stringing after fill cutoff
- ⚠Bottle Filling: Handling foaming products that give false level readings
- ⚠Neglecting to validate Bottle presence sensors (fiber optic or inductive) for container detection leads to control errors
- ⚠Insufficient comments make Sequential Function Charts (SFC) programs unmaintainable over time
Related Certifications
Mastering Sequential Function Charts (SFC) for Bottle Filling applications using Unitronics VisiLogic / UniLogic requires understanding both the platform's capabilities and the specific demands of Packaging. 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 Bottle Filling projects.
Unitronics's 1% market share and moderate - us small-integrator market, oem machines, building automation demonstrate the platform's capability for demanding applications. The platform excels in Packaging applications where Bottle Filling reliability is critical.
By following the practices outlined in this guide—from proper program structure and Sequential Function Charts (SFC) best practices to Unitronics-specific optimizations—you can deliver reliable Bottle Filling systems that meet Packaging requirements.
Next Steps for Professional Development:
1. Certification: Pursue Unitronics Certified Integrator to validate your Unitronics expertise
2. Advanced Training: Consider UniLogic Developer Training for specialized Packaging applications
3. Hands-on Practice: Build Bottle Filling projects using Jazz 2 hardware
4. Stay Current: Follow VisiLogic / UniLogic 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 3-6 weeks typical timeline for Bottle Filling projects will decrease as you gain experience with these patterns and techniques. Remember: Use minimum 10 readings for statistical fill tracking
For further learning, explore related topics including Assembly sequences, Pharmaceutical liquid filling, and Unitronics platform-specific features for Bottle Filling optimization.