Learn PLCs free
Intermediate20 min readInfrastructure

Red Lion Controls Structured Text for Traffic Light Control

Learn Structured Text programming for Traffic Light Control using Red Lion Controls Crimson 3.2. Includes code examples, best practices, and step-by-step implementation guide for Infrastructure applications.

πŸ’»
Platform
Crimson 3.2
πŸ“Š
Complexity
Beginner
⏱️
Project Duration
1-2 weeks

Optimizing Structured Text performance for Traffic Light Control applications in Red Lion Controls's Crimson 3.2 requires understanding both the platform's capabilities and the specific demands of Infrastructure. This guide focuses on proven optimization techniques that deliver measurable improvements in cycle time, reliability, and system responsiveness.

Red Lion Controls's Crimson 3.2 offers powerful tools for Structured Text programming, particularly when targeting beginner applications like Traffic Light Control. With 1% market share and extensive deployment in Panel builders, OEM machines, remote monitoring, rail and transport, Red Lion Controls has refined its platform based on real-world performance requirements from thousands of installations.

Performance considerations for Traffic Light Control systems extend beyond basic functionality. Critical factors include 5 sensor types requiring fast scan times, 4 actuators demanding precise timing, and the need to handle timing optimization. The Structured Text approach addresses these requirements through powerful for complex logic, enabling scan times that meet even demanding Infrastructure applications.

This guide dives deep into optimization strategies including memory management, execution order optimization, Structured Text-specific performance tuning, and Red Lion Controls-specific features that accelerate Traffic Light Control applications. You'll learn techniques used by experienced Red Lion Controls programmers to achieve maximum performance while maintaining code clarity and maintainability.

Red Lion Controls Crimson 3.2 for Traffic Light Control

Crimson 3.2 is Red Lion's free Windows-based IDE covering HMI design, PLC logic (where applicable), protocol conversion, data logging, and edge gateway configuration in a single environment. The FlexEdge DA series extends the traditional HMI-centric product into combined PLC + HMI + protocol-gateway devices, adding IEC 61131-3 ladder and structured text to Crimson's already-rich HMI feature set. Red Lion's historical strength is protocol conversion β€” Modbus, Allen-Bradley, Siemens, Omron, Mitsub...

Platform Strengths for Traffic Light Control:

  • Free Crimson 3.2 IDE with integrated PLC + HMI design

  • FlexEdge DA combines protocol conversion, HMI, and PLC

  • Broad protocol library (Modbus, Allen-Bradley, Siemens, Omron)

  • Rugged hardware for industrial and outdoor use


Unique ${brand.software} Features:

  • Free Crimson 3.2 IDE with HMI, PLC, and protocol gateway design

  • FlexEdge DA series combines PLC + HMI + protocol conversion

  • Built-in drivers for 300+ industrial protocols

  • Strong US panel-builder and OEM machine-builder community


Key Capabilities:

The Crimson 3.2 environment excels at Traffic Light Control applications through its free crimson 3.2 ide with integrated plc + hmi design. This is particularly valuable when working with the 5 sensor types typically found in Traffic Light Control systems, including Vehicle detection loops, Pedestrian buttons, Camera sensors.

Control Equipment for Traffic Light Control:

  • NEMA TS2 or ATC traffic controller cabinets

  • Conflict monitors for signal verification

  • Malfunction management units (MMU)

  • Uninterruptible power supplies (UPS)


Red Lion Controls's controller families for Traffic Light Control include:

  • FlexEdge DA10D: Suitable for beginner Traffic Light Control applications

  • FlexEdge DA30D: Suitable for beginner Traffic Light Control applications

  • FlexEdge DA50D: Suitable for beginner Traffic Light Control applications

  • Graphite HMI: Suitable for beginner Traffic Light Control applications

Hardware Selection Guidance:

Red Lion controller selection spans FlexEdge DA10D (compact form factor, entry-level combined HMI/PLC/gateway), DA30D (mid-range), DA50D (flagship with expanded I/O and networking), Graphite HMI series (pure HMI, pairs with third-party PLCs via protocol conversion), and CR3000 series (dedicated HMI with extensive protocol drivers). Selection depends on required protocol breadth, I/O count, screen ...

Industry Recognition:

Niche - Panel builders, OEM machines, remote monitoring, rail and transport. Red Lion's presence in automotive is primarily in the HMI and protocol-converter functions rather than core PLC control. Red Lion Graphite and FlexEdge panels are common in test cells, specialty tooling, and aftermarket fixtures where multi-protocol translation (Modbus, AB, Siemens, Omron) connects ...

Investment Considerations:

With $$ pricing, Red Lion Controls positions itself in the mid-range segment. For Traffic Light Control projects requiring beginner skill levels and 1-2 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.

Understanding Structured Text for Traffic Light Control

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 Traffic Light Control:

  • Powerful for complex logic: Critical for Traffic Light Control when handling beginner control logic

  • Excellent code reusability: Critical for Traffic Light Control when handling beginner control logic

  • Compact code representation: Critical for Traffic Light Control when handling beginner control logic

  • Good for algorithms and calculations: Critical for Traffic Light Control when handling beginner control logic

  • Familiar to software developers: Critical for Traffic Light Control when handling beginner control logic


Why Structured Text Fits Traffic Light Control:

Traffic Light Control systems in Infrastructure typically involve:

  • Sensors: Inductive loop detectors embedded in pavement for vehicle detection, Video detection cameras with virtual detection zones, Pedestrian push buttons with ADA-compliant features

  • Actuators: LED signal heads for vehicle indications (red, yellow, green, arrows), Pedestrian signal heads (walk, don't walk, countdown), Flashing beacons for warning applications

  • Complexity: Beginner with challenges including Balancing main street progression with side street delay


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 Traffic Light Control
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 Traffic Light Control using Red Lion Controls Crimson 3.2.

Implementing Traffic Light Control with Structured Text

Traffic signal control systems manage the safe and efficient flow of vehicles and pedestrians at intersections. PLCs implement signal timing plans, coordinate with adjacent intersections, respond to traffic demands, and interface with central traffic management systems.

This walkthrough demonstrates practical implementation using Red Lion Controls Crimson 3.2 and Structured Text programming.

System Requirements:

A typical Traffic Light Control implementation includes:

Input Devices (Sensors):
1. Inductive loop detectors embedded in pavement for vehicle detection: Critical for monitoring system state
2. Video detection cameras with virtual detection zones: Critical for monitoring system state
3. Pedestrian push buttons with ADA-compliant features: Critical for monitoring system state
4. Preemption receivers for emergency vehicle detection (optical or radio): Critical for monitoring system state
5. Railroad crossing interconnect signals: Critical for monitoring system state

Output Devices (Actuators):
1. LED signal heads for vehicle indications (red, yellow, green, arrows): Primary control output
2. Pedestrian signal heads (walk, don't walk, countdown): Supporting control function
3. Flashing beacons for warning applications: Supporting control function
4. Advance warning flashers: Supporting control function
5. Cabinet cooling fans and environmental controls: Supporting control function

Control Equipment:

  • NEMA TS2 or ATC traffic controller cabinets

  • Conflict monitors for signal verification

  • Malfunction management units (MMU)

  • Uninterruptible power supplies (UPS)


Control Strategies for Traffic Light Control:

1. Primary Control: Automated traffic signal control using PLCs for intersection management, timing optimization, and pedestrian safety.
2. Safety Interlocks: Preventing Timing optimization
3. Error Recovery: Handling Emergency vehicle priority

Implementation Steps:

Step 1: Survey intersection geometry and traffic patterns

In Crimson 3.2, survey intersection geometry and traffic patterns.

Step 2: Define phases and rings per NEMA/ATC standards

In Crimson 3.2, define phases and rings per nema/atc standards.

Step 3: Calculate minimum and maximum green times for each phase

In Crimson 3.2, calculate minimum and maximum green times for each phase.

Step 4: Implement detector logic with extending and presence modes

In Crimson 3.2, implement detector logic with extending and presence modes.

Step 5: Program phase sequencing with proper clearance intervals

In Crimson 3.2, program phase sequencing with proper clearance intervals.

Step 6: Add pedestrian phases with accessible pedestrian signals

In Crimson 3.2, add pedestrian phases with accessible pedestrian signals.


Red Lion Controls Function Design:

Crimson projects use reusable 'programs' (Crimson's unit of logic code) with parameters. Library management is more basic than in mainstream IEC ecosystems; OEMs typically maintain private project templates and copy-adapt rather than importing shared libraries. FlexEdge DA's IEC PLC portion follows standard IEC 61131-3 function-block reuse patterns.

Common Challenges and Solutions:

1. Balancing main street progression with side street delay

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


2. Handling varying traffic demands throughout the day

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


3. Providing adequate pedestrian crossing time

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


4. Managing detector failures gracefully

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


Safety Considerations:

  • Conflict monitoring to detect improper signal states

  • Yellow and all-red clearance intervals per engineering standards

  • Flashing operation mode for controller failures

  • Pedestrian minimum walk and clearance times per MUTCD

  • Railroad preemption for track clearance


Performance Metrics:

  • Scan Time: Optimize for 5 inputs and 4 outputs

  • Memory Usage: Efficient data structures for FlexEdge DA10D capabilities

  • Response Time: Meeting Infrastructure requirements for Traffic Light Control

Red Lion Controls Diagnostic Tools:

Crimson 3.2 integrated debugger with tag monitoring and simulation mode,Built-in data-logging diagnostics with local and network-export options,Integrated communication analyzer for every supported driver (300+ protocols),FlexEdge webserver for remote HMI mirroring and device-level diagnostics,Visual logic debugger for Crimson logic (event-driven rather than scan-based),Real-time tag watch with filtering and grouping,Database import/export for tag-database migration and diffing,N-Tron managed switch diagnostics integrated with FlexEdge ecosystem,Red Lion US-based technical support,Crimson help system with protocol-specific driver documentation inline

Red Lion Controls's Crimson 3.2 provides tools for performance monitoring and optimization, essential for achieving the 1-2 weeks development timeline while maintaining code quality.

Red Lion Controls Structured Text Example for Traffic Light Control

Complete working example demonstrating Structured Text implementation for Traffic Light Control using Red Lion Controls Crimson 3.2. Follows Red Lion Controls naming conventions. Tested on FlexEdge DA10D hardware.

(* Red Lion Controls Crimson 3.2 - Traffic Light Control Control *)
(* Structured Text Implementation for Infrastructure *)
(* Red Lion projects use Crimson's tag database with typed tags and descr *)

PROGRAM PRG_TRAFFIC_LIGHT_CONTROL_Control

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

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

    (* Counters *)
    ctuCycleCounter : CTU;

    (* Process Variables *)
    rVehicledetectionloops : REAL := 0.0;
    rLEDtrafficsignals : REAL := 0.0;
    rSetpoint : REAL := 100.0;
END_VAR

VAR CONSTANT
    (* Infrastructure 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: State machines in Crimson are typically  *)
CASE eState OF
    IDLE:
        rLEDtrafficsignals := 0.0;
        ctuCycleCounter(RESET := TRUE);
        IF bEnable AND rVehicledetectionloops > 0.0 THEN
            eState := STARTING;
        END_IF;

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

    RUNNING:
        (* Traffic Light Control active - Traffic signal control systems manage the safe and *)
        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:
        rLEDtrafficsignals := 0.0;
        (* Log production data - Data logging uses Crimson's built-in Logger β€” configured periodic or event-triggered records written to local SD card, networked SFTP, or cloud endpoints in CSV or JSON format. Integration with database historians is supported through standard protocols. For FlexEdge, integration with N-Tron switches and the wider Red Lion data ecosystem supports site-wide aggregation. *)
        eState := IDLE;

    FAULT:
        rLEDtrafficsignals := 0.0;
        (* Alarm handling uses Crimson's built-in Alarm Manager β€” configured alarm conditions with severity, message text, logging, and HMI display behaviour. The alarm engine handles detection, acknowledgement, and history without custom code. Integration with email, SMS, or external alarm aggregators is configured via Crimson's notification features. *)
        IF bFaultReset AND NOT bEmergencyStop THEN
            bFaultActive := FALSE;
            eState := IDLE;
        END_IF;
END_CASE;

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

END_PROGRAM

Code Explanation:

  • 1.Enumerated state machine (State machines in Crimson are typically implemented using tag-based state variables with event-driven logic checking the state on each event. The event-driven model maps naturally to state-transition logic. FlexEdge DA's IEC PLC portion uses standard CASE-based state machines in ST when PLC-side sequencing is required.) for clear Traffic Light Control sequence control
  • 2.Constants define Infrastructure-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 - Red Lion Controls best practice for beginner systems

Best Practices

  • βœ“Follow Red Lion Controls naming conventions: Red Lion projects use Crimson's tag database with typed tags and descriptive nam
  • βœ“Red Lion Controls function design: Crimson projects use reusable 'programs' (Crimson's unit of logic code) with par
  • βœ“Data organization: Crimson tag databases hold typed tags with scope (Global, Alarm, Report, etc.) a
  • βœ“Structured Text: Use meaningful variable names with consistent naming conventions
  • βœ“Structured Text: Initialize all variables at declaration to prevent undefined behavior
  • βœ“Structured Text: Use enumerated types for state machines instead of magic numbers
  • βœ“Traffic Light Control: Use passage time (extension) values based on approach speed
  • βœ“Traffic Light Control: Implement detector failure fallback to recall or maximum timing
  • βœ“Traffic Light Control: Log all phase changes and detector events for analysis
  • βœ“Debug with Crimson 3.2: Use Crimson 3.2's simulation mode to test HMI and logic before deployi
  • βœ“Safety: Conflict monitoring to detect improper signal states
  • βœ“Use Crimson 3.2 simulation tools to test Traffic Light Control 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
  • ⚠Red Lion Controls common error: Crimson version-to-firmware compatibility issues after hardware firmware upgrade
  • ⚠Traffic Light Control: Balancing main street progression with side street delay
  • ⚠Traffic Light Control: Handling varying traffic demands throughout the day
  • ⚠Neglecting to validate Inductive loop detectors embedded in pavement for vehicle detection leads to control errors
  • ⚠Insufficient comments make Structured Text programs unmaintainable over time

Related Certifications

πŸ†Red Lion Crimson Certified Engineer
πŸ†Red Lion Specialist Training
πŸ†Advanced Red Lion Controls Programming Certification

Mastering Structured Text for Traffic Light Control applications using Red Lion Controls Crimson 3.2 requires understanding both the platform's capabilities and the specific demands of Infrastructure. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with beginner Traffic Light Control projects.

Red Lion Controls's 1% market share and niche - panel builders, oem machines, remote monitoring, rail and transport demonstrate the platform's capability for demanding applications. The platform excels in Infrastructure applications where Traffic Light Control reliability is critical.

By following the practices outlined in this guideβ€”from proper program structure and Structured Text best practices to Red Lion Controls-specific optimizationsβ€”you can deliver reliable Traffic Light Control systems that meet Infrastructure requirements.

Next Steps for Professional Development:

1. Certification: Pursue Red Lion Crimson Certified Engineer to validate your Red Lion Controls expertise
2. Advanced Training: Consider Red Lion Specialist Training for specialized Infrastructure applications
3. Hands-on Practice: Build Traffic Light Control projects using FlexEdge DA10D hardware
4. Stay Current: Follow Crimson 3.2 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 1-2 weeks typical timeline for Traffic Light Control projects will decrease as you gain experience with these patterns and techniques. Remember: Use passage time (extension) values based on approach speed

For further learning, explore related topics including Recipe management, Highway ramp metering, and Red Lion Controls platform-specific features for Traffic Light Control optimization.