Intermediate25 min readManufacturing

ABB Structured Text for Assembly Lines

Learn Structured Text programming for Assembly Lines using ABB Automation Builder. Includes code examples, best practices, and step-by-step implementation guide for Manufacturing applications.

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Platform
Automation Builder
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Complexity
Intermediate to Advanced
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Project Duration
4-8 weeks
Learning to implement Structured Text for Assembly Lines using ABB's Automation Builder is an essential skill for PLC programmers working in Manufacturing. This comprehensive guide walks you through the fundamentals, providing clear explanations and practical examples that you can apply immediately to real-world projects. ABB has established itself as Medium - Strong in power generation, mining, and marine applications, making it a strategic choice for Assembly Lines applications. With 8% global market share and 3 popular PLC families including the AC500 and AC500-eCo, ABB provides the robust platform needed for intermediate to advanced complexity projects like Assembly Lines. The Structured Text approach is particularly well-suited for Assembly Lines because complex calculations, data manipulation, advanced control algorithms, and when code reusability is important. This combination allows you to leverage powerful for complex logic while managing the typical challenges of Assembly Lines, including cycle time optimization and quality inspection. Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on Automation Builder, and industry best practices specific to Manufacturing. Whether you're programming your first Assembly Lines system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with ABB Structured Text programming.

ABB Automation Builder for Assembly Lines

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 Assembly Lines:

  • 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 Assembly Lines applications through its excellent for robotics integration. This is particularly valuable when working with the 5 sensor types typically found in Assembly Lines systems, including Vision systems, Proximity sensors, Force sensors.

Control Equipment for Assembly Lines:

  • Assembly workstations with fixtures

  • Pallet transfer systems

  • Automated guided vehicles (AGVs)

  • Collaborative robots (cobots)


ABB's controller families for Assembly Lines include:

  • AC500: Suitable for intermediate to advanced Assembly Lines applications

  • AC500-eCo: Suitable for intermediate to advanced Assembly Lines applications

  • AC500-S: Suitable for intermediate to advanced Assembly Lines 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 Assembly Lines projects requiring advanced skill levels and 4-8 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.

Understanding Structured Text for Assembly Lines

Structured Text (ST) is a high-level, text-based programming language defined in IEC 61131-3. It resembles Pascal and provides powerful constructs for complex algorithms, calculations, and data manipulation.

Execution Model:

Code executes sequentially from top to bottom within each program unit. Variables maintain state between scan cycles unless explicitly reset.

Core Advantages for Assembly Lines:

  • Powerful for complex logic: Critical for Assembly Lines when handling intermediate to advanced control logic

  • Excellent code reusability: Critical for Assembly Lines when handling intermediate to advanced control logic

  • Compact code representation: Critical for Assembly Lines when handling intermediate to advanced control logic

  • Good for algorithms and calculations: Critical for Assembly Lines when handling intermediate to advanced control logic

  • Familiar to software developers: Critical for Assembly Lines when handling intermediate to advanced control logic


Why Structured Text Fits Assembly Lines:

Assembly Lines systems in Manufacturing typically involve:

  • Sensors: Part presence sensors for component verification, Proximity sensors for fixture and tooling position, Torque sensors for fastener verification

  • Actuators: Pneumatic clamps and fixtures, Electric torque tools with controllers, Pick-and-place mechanisms

  • Complexity: Intermediate to Advanced with challenges including Balancing work content across stations for consistent cycle time


Programming Fundamentals in Structured Text:

Variables:
- declaration: VAR / VAR_INPUT / VAR_OUTPUT / VAR_IN_OUT / VAR_GLOBAL sections
- initialization: Variables can be initialized at declaration: Counter : INT := 0;
- constants: VAR CONSTANT section for read-only values

Operators:
- arithmetic: + - * / MOD (modulo)
- comparison: = <> < > <= >=
- logical: AND OR XOR NOT

ControlStructures:
- if: IF condition THEN statements; ELSIF condition THEN statements; ELSE statements; END_IF;
- case: CASE selector OF value1: statements; value2: statements; ELSE statements; END_CASE;
- for: FOR index := start TO end BY step DO statements; END_FOR;

Best Practices for Structured Text:

  • Use meaningful variable names with consistent naming conventions

  • Initialize all variables at declaration to prevent undefined behavior

  • Use enumerated types for state machines instead of magic numbers

  • Break complex expressions into intermediate variables for readability

  • Use functions for reusable calculations and function blocks for stateful operations


Common Mistakes to Avoid:

  • Using = instead of := for assignment (= is comparison)

  • Forgetting semicolons at end of statements

  • Integer division truncation - use REAL for decimal results

  • Infinite loops from incorrect WHILE/REPEAT conditions


Typical Applications:

1. PID control: Directly applicable to Assembly Lines
2. Recipe management: Related control patterns
3. Statistical calculations: Related control patterns
4. Data logging: Related control patterns

Understanding these fundamentals prepares you to implement effective Structured Text solutions for Assembly Lines using ABB Automation Builder.

Implementing Assembly Lines with Structured Text

Assembly line control systems coordinate the sequential addition of components to products as they move through workstations. PLCs manage station sequencing, operator interfaces, quality verification, and production tracking for efficient manufacturing.

This walkthrough demonstrates practical implementation using ABB Automation Builder and Structured Text programming.

System Requirements:

A typical Assembly Lines implementation includes:

Input Devices (Sensors):
1. Part presence sensors for component verification: Critical for monitoring system state
2. Proximity sensors for fixture and tooling position: Critical for monitoring system state
3. Torque sensors for fastener verification: Critical for monitoring system state
4. Vision systems for assembly inspection: Critical for monitoring system state
5. Barcode/RFID readers for part tracking: Critical for monitoring system state

Output Devices (Actuators):
1. Pneumatic clamps and fixtures: Primary control output
2. Electric torque tools with controllers: Supporting control function
3. Pick-and-place mechanisms: Supporting control function
4. Servo presses for precision insertion: Supporting control function
5. Indexing conveyors and pallets: Supporting control function

Control Equipment:

  • Assembly workstations with fixtures

  • Pallet transfer systems

  • Automated guided vehicles (AGVs)

  • Collaborative robots (cobots)


Control Strategies for Assembly Lines:

1. Primary Control: Automated production assembly using PLCs for part handling, quality control, and production tracking.
2. Safety Interlocks: Preventing Cycle time optimization
3. Error Recovery: Handling Quality inspection

Implementation Steps:

Step 1: Document assembly sequence with cycle time targets per station

In Automation Builder, document assembly sequence with cycle time targets per station.

Step 2: Define product variants and option configurations

In Automation Builder, define product variants and option configurations.

Step 3: Create I/O list for all sensors, actuators, and operator interfaces

In Automation Builder, create i/o list for all sensors, actuators, and operator interfaces.

Step 4: Implement station control logic with proper sequencing

In Automation Builder, implement station control logic with proper sequencing.

Step 5: Add poka-yoke (error-proofing) verification for critical operations

In Automation Builder, add poka-yoke (error-proofing) verification for critical operations.

Step 6: Program operator interface for cycle start, completion, and fault handling

In Automation Builder, program operator interface for cycle start, completion, and fault handling.


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. Balancing work content across stations for consistent cycle time

  • Solution: Structured Text addresses this through Powerful for complex logic.


2. Handling product variants with different operations

  • Solution: Structured Text addresses this through Excellent code reusability.


3. Managing parts supply and preventing stock-outs

  • Solution: Structured Text addresses this through Compact code representation.


4. Recovering from faults while maintaining quality

  • Solution: Structured Text addresses this through Good for algorithms and calculations.


Safety Considerations:

  • Two-hand start buttons for manual stations

  • Light curtain muting for parts entry without stopping

  • Safe motion for collaborative robot operations

  • Lockout/tagout provisions for maintenance

  • Emergency stop zoning for partial line operation


Performance Metrics:

  • Scan Time: Optimize for 5 inputs and 5 outputs

  • Memory Usage: Efficient data structures for AC500 capabilities

  • Response Time: Meeting Manufacturing requirements for Assembly Lines

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 4-8 weeks development timeline while maintaining code quality.

ABB Structured Text Example for Assembly Lines

Complete working example demonstrating Structured Text implementation for Assembly Lines using ABB Automation Builder. Follows ABB naming conventions. Tested on AC500 hardware.

(* ABB Automation Builder - Assembly Lines Control *)
(* Structured Text Implementation for Manufacturing *)
(* g_ prefix for globals. i_/q_ for FB I/O. Type prefixes: b=BOOL, n=INT, *)

PROGRAM PRG_ASSEMBLY_LINES_Control

VAR
    (* State Machine Variables *)
    eState : E_ASSEMBLY_LINES_States := IDLE;
    bEnable : BOOL := FALSE;
    bFaultActive : BOOL := FALSE;

    (* Timers *)
    tonDebounce : TON;
    tonProcessTimeout : TON;
    tonFeedbackCheck : TON;

    (* Counters *)
    ctuCycleCounter : CTU;

    (* Process Variables *)
    rVisionsystems : REAL := 0.0;
    rServomotors : REAL := 0.0;
    rSetpoint : REAL := 100.0;
END_VAR

VAR CONSTANT
    (* Manufacturing Process Parameters *)
    C_DEBOUNCE_TIME : TIME := T#500MS;
    C_PROCESS_TIMEOUT : TIME := T#30S;
    C_BATCH_SIZE : INT := 50;
END_VAR

(* Input Conditioning *)
tonDebounce(IN := bStartButton, PT := C_DEBOUNCE_TIME);
bEnable := tonDebounce.Q AND NOT bEmergencyStop AND bSafetyOK;

(* Main State Machine - Pattern: CASE eState OF IDLE: IF bStartCmd THEN e *)
CASE eState OF
    IDLE:
        rServomotors := 0.0;
        ctuCycleCounter(RESET := TRUE);
        IF bEnable AND rVisionsystems > 0.0 THEN
            eState := STARTING;
        END_IF;

    STARTING:
        (* Ramp up output - Gradual start *)
        rServomotors := MIN(rServomotors + 5.0, rSetpoint);
        IF rServomotors >= rSetpoint THEN
            eState := RUNNING;
        END_IF;

    RUNNING:
        (* Assembly Lines active - Assembly line control systems coordinate the seque *)
        tonProcessTimeout(IN := TRUE, PT := C_PROCESS_TIMEOUT);
        ctuCycleCounter(CU := bCyclePulse, PV := C_BATCH_SIZE);

        IF ctuCycleCounter.Q THEN
            eState := COMPLETE;
        ELSIF tonProcessTimeout.Q THEN
            bFaultActive := TRUE;
            eState := FAULT;
        END_IF;

    COMPLETE:
        rServomotors := 0.0;
        (* Log production data - Circular buffer with ST_LogRecord. Write index with modulo wrap. Triggered capture with pre/post samples. File export using file system library. *)
        eState := IDLE;

    FAULT:
        rServomotors := 0.0;
        (* ST_Alarm structure with bActive, bAcknowledged, dtActivation, nCode, sMessage. Array of alarms with detection and acknowledgment logic. Integration with ABB alarm libraries. *)
        IF bFaultReset AND NOT bEmergencyStop THEN
            bFaultActive := FALSE;
            eState := IDLE;
        END_IF;
END_CASE;

(* Safety Override - Always executes *)
IF bEmergencyStop OR NOT bSafetyOK THEN
    rServomotors := 0.0;
    eState := FAULT;
    bFaultActive := TRUE;
END_IF;

END_PROGRAM

Code Explanation:

  • 1.Enumerated state machine (CASE eState OF IDLE: IF bStartCmd THEN eState := STARTING; END_IF; STARTING: tonStarting(IN := TRUE, PT := T#10S); IF bRunConfirm THEN eState := RUNNING; END_IF; END_CASE; Log transitions.) for clear Assembly Lines sequence control
  • 2.Constants define Manufacturing-specific parameters: cycle time 30s, batch size
  • 3.Input conditioning with debounce timer prevents false triggers in industrial environment
  • 4.STARTING state implements soft-start ramp - prevents mechanical shock
  • 5.Process timeout detection identifies stuck conditions - critical for reliability
  • 6.Safety override section executes regardless of state - ABB best practice for intermediate to advanced systems

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
  • Structured Text: Use meaningful variable names with consistent naming conventions
  • Structured Text: Initialize all variables at declaration to prevent undefined behavior
  • Structured Text: Use enumerated types for state machines instead of magic numbers
  • Assembly Lines: Implement operation-level process data logging
  • Assembly Lines: Use standard station control template for consistency
  • Assembly Lines: Add pre-emptive parts request to avoid stock-out
  • Debug with Automation Builder: Use structured logging to controller log
  • Safety: Two-hand start buttons for manual stations
  • Use Automation Builder simulation tools to test Assembly Lines logic before deployment

Common Pitfalls to Avoid

  • Structured Text: Using = instead of := for assignment (= is comparison)
  • Structured Text: Forgetting semicolons at end of statements
  • Structured Text: Integer division truncation - use REAL for decimal results
  • ABB common error: Exception 'AccessViolation': Null pointer access
  • Assembly Lines: Balancing work content across stations for consistent cycle time
  • Assembly Lines: Handling product variants with different operations
  • Neglecting to validate Part presence sensors for component verification leads to control errors
  • Insufficient comments make Structured Text programs unmaintainable over time

Related Certifications

🏆ABB Automation Certification
🏆Advanced ABB Programming Certification
Mastering Structured Text for Assembly Lines applications using ABB Automation Builder requires understanding both the platform's capabilities and the specific demands of Manufacturing. 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 Assembly Lines 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 Manufacturing applications where Assembly Lines reliability is critical. By following the practices outlined in this guide—from proper program structure and Structured Text best practices to ABB-specific optimizations—you can deliver reliable Assembly Lines systems that meet Manufacturing requirements. **Next Steps for Professional Development:** 1. **Certification**: Pursue ABB Automation Certification to validate your ABB expertise 3. **Hands-on Practice**: Build Assembly Lines projects using AC500 hardware 4. **Stay Current**: Follow Automation Builder updates and new Structured Text features **Structured Text Foundation:** Structured Text (ST) is a high-level, text-based programming language defined in IEC 61131-3. It resembles Pascal and provides powerful constructs for... The 4-8 weeks typical timeline for Assembly Lines projects will decrease as you gain experience with these patterns and techniques. Remember: Implement operation-level process data logging For further learning, explore related topics including Recipe management, Electronics manufacturing, and ABB platform-specific features for Assembly Lines optimization.