Intermediate15 min readProcess Control

ABB Sequential Function Charts (SFC) for Temperature Control

Learn Sequential Function Charts (SFC) programming for Temperature Control using ABB Automation Builder. Includes code examples, best practices, and step-by-step implementation guide for Process Control applications.

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Platform
Automation Builder
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Complexity
Intermediate
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Project Duration
2-3 weeks
Optimizing Sequential Function Charts (SFC) performance for Temperature Control applications in ABB's Automation Builder requires understanding both the platform's capabilities and the specific demands of Process Control. This guide focuses on proven optimization techniques that deliver measurable improvements in cycle time, reliability, and system responsiveness. ABB's Automation Builder offers powerful tools for Sequential Function Charts (SFC) programming, particularly when targeting intermediate applications like Temperature Control. With 8% market share and extensive deployment in Strong in power generation, mining, and marine applications, ABB has refined its platform based on real-world performance requirements from thousands of installations. Performance considerations for Temperature Control systems extend beyond basic functionality. Critical factors include 4 sensor types requiring fast scan times, 5 actuators demanding precise timing, and the need to handle pid tuning. The Sequential Function Charts (SFC) approach addresses these requirements through perfect for sequential processes, enabling scan times that meet even demanding Process Control applications. This guide dives deep into optimization strategies including memory management, execution order optimization, Sequential Function Charts (SFC)-specific performance tuning, and ABB-specific features that accelerate Temperature Control applications. You'll learn techniques used by experienced ABB programmers to achieve maximum performance while maintaining code clarity and maintainability.

ABB Automation Builder for Temperature Control

Automation Builder provides ABB's unified environment for AC500 PLC programming, drive configuration, and HMI development. Built on CODESYS V3 with ABB-specific enhancements. Strength lies in seamless drive integration with ACS880 and other families....

Platform Strengths for Temperature Control:

  • Excellent for robotics integration

  • Strong in power and utilities

  • Robust hardware for harsh environments

  • Good scalability


Unique ${brand.software} Features:

  • Integrated drive configuration for ACS880, ACS580 drives

  • Extensive application libraries: HVAC, pumping, conveying, crane control

  • Safety programming for AC500-S within standard project

  • Panel Builder 600 HMI development integrated


Key Capabilities:

The Automation Builder environment excels at Temperature Control applications through its excellent for robotics integration. This is particularly valuable when working with the 4 sensor types typically found in Temperature Control systems, including Thermocouples (K-type, J-type), RTD sensors (PT100, PT1000), Infrared temperature sensors.

Control Equipment for Temperature Control:

  • Electric resistance heaters (cartridge, band, strip)

  • Steam injection systems

  • Thermal fluid (hot oil) systems

  • Refrigeration and chiller systems


ABB's controller families for Temperature Control include:

  • AC500: Suitable for intermediate Temperature Control applications

  • AC500-eCo: Suitable for intermediate Temperature Control applications

  • AC500-S: Suitable for intermediate Temperature Control applications

Hardware Selection Guidance:

PM554 entry-level for simple applications. PM564 mid-range for OEM machines. PM573 high-performance for complex algorithms. PM5 series latest generation with cloud connectivity. AC500-S for integrated safety....

Industry Recognition:

Medium - Strong in power generation, mining, and marine applications. AC500 coordinating VFD-controlled motors with ACS880 drives. Energy optimization reducing consumption 25-40%. Robot integration via ABB robot interfaces. Press line automation with AC500-S safety....

Investment Considerations:

With $$ pricing, ABB positions itself in the mid-range segment. For Temperature Control projects requiring intermediate skill levels and 2-3 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.

Understanding Sequential Function Charts (SFC) for Temperature 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 Temperature Control:

  • Perfect for sequential processes: Critical for Temperature Control when handling intermediate control logic

  • Clear visualization of process flow: Critical for Temperature Control when handling intermediate control logic

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

  • Good for batch operations: Critical for Temperature Control when handling intermediate control logic

  • Simplifies complex sequences: Critical for Temperature Control when handling intermediate control logic


Why Sequential Function Charts (SFC) Fits Temperature Control:

Temperature Control systems in Process Control typically involve:

  • Sensors: RTDs (PT100/PT1000) for high-accuracy measurements, Thermocouples (J, K, T types) for high-temperature applications, Infrared pyrometers for non-contact measurement

  • Actuators: SCR (thyristor) power controllers for electric heaters, Solid-state relays for on/off heating control, Proportional control valves for steam or thermal fluid

  • Complexity: Intermediate with challenges including Long thermal time constants making tuning difficult


Control Strategies for Temperature Control:

  • pid: Standard PID control with proportional, integral, and derivative terms tuned for the thermal process dynamics

  • cascade: Master temperature loop outputs to slave heater/cooler control loop for tighter control

  • ratio: Maintain temperature ratio between zones for gradient applications


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 Temperature 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 Temperature Control using ABB Automation Builder.

Implementing Temperature Control with Sequential Function Charts (SFC)

Industrial temperature control systems use PLCs to regulate process temperatures in manufacturing, food processing, chemical processing, and other applications. These systems maintain precise temperature setpoints through heating and cooling control while ensuring product quality and energy efficiency.

This walkthrough demonstrates practical implementation using ABB Automation Builder and Sequential Function Charts (SFC) programming.

System Requirements:

A typical Temperature Control implementation includes:

Input Devices (Sensors):
1. RTDs (PT100/PT1000) for high-accuracy measurements: Critical for monitoring system state
2. Thermocouples (J, K, T types) for high-temperature applications: Critical for monitoring system state
3. Infrared pyrometers for non-contact measurement: Critical for monitoring system state
4. Thermistors for fast response applications: Critical for monitoring system state
5. Thermal imaging cameras for surface temperature monitoring: Critical for monitoring system state

Output Devices (Actuators):
1. SCR (thyristor) power controllers for electric heaters: Primary control output
2. Solid-state relays for on/off heating control: Supporting control function
3. Proportional control valves for steam or thermal fluid: Supporting control function
4. Solenoid valves for cooling water or refrigerant: Supporting control function
5. Variable frequency drives for cooling fan control: Supporting control function

Control Equipment:

  • Electric resistance heaters (cartridge, band, strip)

  • Steam injection systems

  • Thermal fluid (hot oil) systems

  • Refrigeration and chiller systems


Control Strategies for Temperature Control:

  • pid: Standard PID control with proportional, integral, and derivative terms tuned for the thermal process dynamics

  • cascade: Master temperature loop outputs to slave heater/cooler control loop for tighter control

  • ratio: Maintain temperature ratio between zones for gradient applications


Implementation Steps:

Step 1: Characterize thermal system dynamics (time constants, dead time)

In Automation Builder, characterize thermal system dynamics (time constants, dead time).

Step 2: Select appropriate sensor type and placement for representative measurement

In Automation Builder, select appropriate sensor type and placement for representative measurement.

Step 3: Size heating and cooling capacity for worst-case load conditions

In Automation Builder, size heating and cooling capacity for worst-case load conditions.

Step 4: Implement PID control with appropriate sample time (typically 10x faster than process time constant)

In Automation Builder, implement pid control with appropriate sample time (typically 10x faster than process time constant).

Step 5: Add output limiting and anti-windup for safe operation

In Automation Builder, add output limiting and anti-windup for safe operation.

Step 6: Program ramp/soak profiles if required

In Automation Builder, program ramp/soak profiles if required.


ABB Function Design:

Standard FB structure with VAR_INPUT/OUTPUT/VAR. Methods extend functionality. ABB application libraries provide tested FBs. Drive FBs wrap drive parameter access.

Common Challenges and Solutions:

1. Long thermal time constants making tuning difficult

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


2. Transport delay (dead time) causing instability

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


3. Non-linear response at different temperature ranges

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


4. Sensor placement affecting measurement accuracy

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


Safety Considerations:

  • Independent high-limit safety thermostats (redundant to PLC)

  • Watchdog timers for heater control validity

  • Safe-state definition on controller failure (heaters off)

  • Thermal fuse backup for runaway conditions

  • Proper ventilation for combustible atmospheres


Performance Metrics:

  • Scan Time: Optimize for 4 inputs and 5 outputs

  • Memory Usage: Efficient data structures for AC500 capabilities

  • Response Time: Meeting Process Control requirements for Temperature Control

ABB Diagnostic Tools:

Online monitoring with live values,Watch window with expressions,Breakpoints for inspection,Drive diagnostics showing fault history,Communication diagnostics for network statistics

ABB's Automation Builder provides tools for performance monitoring and optimization, essential for achieving the 2-3 weeks development timeline while maintaining code quality.

ABB Sequential Function Charts (SFC) Example for Temperature Control

Complete working example demonstrating Sequential Function Charts (SFC) implementation for Temperature Control using ABB Automation Builder. Follows ABB naming conventions. Tested on AC500 hardware.

// ABB Automation Builder - Temperature Control Control
// Sequential Function Charts (SFC) Implementation for Process Control
// g_ prefix for globals. i_/q_ for FB I/O. Type prefixes: b=BO

// ============================================
// Variable Declarations
// ============================================
VAR
    bEnable : BOOL := FALSE;
    bEmergencyStop : BOOL := FALSE;
    rThermocouplesKtypeJtype : REAL;
    rHeatingelements : REAL;
END_VAR

// ============================================
// Input Conditioning - RTDs (PT100/PT1000) for high-accuracy measurements
// ============================================
// Standard input processing
IF rThermocouplesKtypeJtype > 0.0 THEN
    bEnable := TRUE;
END_IF;

// ============================================
// Safety Interlock - Independent high-limit safety thermostats (redundant to PLC)
// ============================================
IF bEmergencyStop THEN
    rHeatingelements := 0.0;
    bEnable := FALSE;
END_IF;

// ============================================
// Main Temperature Control Control Logic
// ============================================
IF bEnable AND NOT bEmergencyStop THEN
    // Industrial temperature control systems use PLCs to regulate 
    rHeatingelements := rThermocouplesKtypeJtype * 1.0;

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

Code Explanation:

  • 1.Sequential Function Charts (SFC) structure optimized for Temperature Control in Process Control applications
  • 2.Input conditioning handles RTDs (PT100/PT1000) for high-accuracy measurements signals
  • 3.Safety interlock ensures Independent high-limit safety thermostats (redundant to PLC) always takes priority
  • 4.Main control implements Industrial temperature control systems u
  • 5.Code runs every scan cycle on AC500 (typically 5-20ms)

Best Practices

  • Follow ABB naming conventions: g_ prefix for globals. i_/q_ for FB I/O. Type prefixes: b=BOOL, n=INT, r=REAL, s
  • ABB function design: Standard FB structure with VAR_INPUT/OUTPUT/VAR. Methods extend functionality. A
  • Data organization: DUTs define structures. GVLs group related data. Retain attribute preserves vari
  • 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
  • Temperature Control: Sample at 1/10 of the process time constant minimum
  • Temperature Control: Use derivative on PV, not error, for temperature control
  • Temperature Control: Start with conservative tuning and tighten gradually
  • Debug with Automation Builder: Use structured logging to controller log
  • Safety: Independent high-limit safety thermostats (redundant to PLC)
  • Use Automation Builder simulation tools to test Temperature 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
  • ABB common error: Exception 'AccessViolation': Null pointer access
  • Temperature Control: Long thermal time constants making tuning difficult
  • Temperature Control: Transport delay (dead time) causing instability
  • Neglecting to validate RTDs (PT100/PT1000) for high-accuracy measurements leads to control errors
  • Insufficient comments make Sequential Function Charts (SFC) programs unmaintainable over time

Related Certifications

🏆ABB Automation Certification
Mastering Sequential Function Charts (SFC) for Temperature Control applications using ABB Automation Builder requires understanding both the platform's capabilities and the specific demands of Process Control. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with intermediate Temperature Control projects. ABB's 8% market share and medium - strong in power generation, mining, and marine applications demonstrate the platform's capability for demanding applications. The platform excels in Process Control applications where Temperature Control reliability is critical. By following the practices outlined in this guide—from proper program structure and Sequential Function Charts (SFC) best practices to ABB-specific optimizations—you can deliver reliable Temperature Control systems that meet Process Control requirements. **Next Steps for Professional Development:** 1. **Certification**: Pursue ABB Automation Certification to validate your ABB expertise 3. **Hands-on Practice**: Build Temperature Control projects using AC500 hardware 4. **Stay Current**: Follow Automation Builder 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 2-3 weeks typical timeline for Temperature Control projects will decrease as you gain experience with these patterns and techniques. Remember: Sample at 1/10 of the process time constant minimum For further learning, explore related topics including Assembly sequences, Plastic molding machines, and ABB platform-specific features for Temperature Control optimization.