Learning to implement Function Blocks for Sensor Integration using Unitronics's VisiLogic / UniLogic is an essential skill for PLC programmers working in Universal. 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 Sensor Integration 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 beginner to intermediate complexity projects like Sensor Integration.
The Function Blocks approach is particularly well-suited for Sensor Integration because process control, continuous operations, modular programming, and signal flow visualization. This combination allows you to leverage visual representation of signal flow while managing the typical challenges of Sensor Integration, including signal conditioning and sensor calibration.
Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on VisiLogic / UniLogic, and industry best practices specific to Universal. Whether you're programming your first Sensor Integration system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with Unitronics Function Blocks programming.
Unitronics VisiLogic / UniLogic for Sensor Integration
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 Sensor Integration:
- 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 Sensor Integration 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 Sensor Integration systems, including Analog sensors (4-20mA, 0-10V), Digital sensors (NPN, PNP), Smart sensors (IO-Link).
Unitronics's controller families for Sensor Integration include:
- Jazz 2: Suitable for beginner to intermediate Sensor Integration applications
- Samba 7": Suitable for beginner to intermediate Sensor Integration applications
- Vision V350: Suitable for beginner to intermediate Sensor Integration applications
- Vision V570: Suitable for beginner to intermediate Sensor Integration 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 Sensor Integration projects requiring beginner skill levels and 1-2 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.
Understanding Function Blocks for Sensor Integration
Function Block Diagram (FBD) is a graphical programming language where functions and function blocks are represented as boxes connected by signal lines. Data flows from left to right through the network.
Execution Model:
Blocks execute based on data dependencies - a block executes only when all its inputs are available. Networks execute top to bottom when dependencies allow.
Core Advantages for Sensor Integration:
- Visual representation of signal flow: Critical for Sensor Integration when handling beginner to intermediate control logic
- Good for modular programming: Critical for Sensor Integration when handling beginner to intermediate control logic
- Reusable components: Critical for Sensor Integration when handling beginner to intermediate control logic
- Excellent for process control: Critical for Sensor Integration when handling beginner to intermediate control logic
- Good for continuous operations: Critical for Sensor Integration when handling beginner to intermediate control logic
Why Function Blocks Fits Sensor Integration:
Sensor Integration systems in Universal typically involve:
- Sensors: Discrete sensors (proximity, photoelectric, limit switches), Analog sensors (4-20mA, 0-10V transmitters), Temperature sensors (RTD, thermocouple, thermistor)
- Actuators: Not applicable - focus on input processing
- Complexity: Beginner to Intermediate with challenges including Electrical noise affecting analog signals
Programming Fundamentals in Function Blocks:
StandardBlocks:
- logic: AND, OR, XOR, NOT - Boolean logic operations
- comparison: EQ, NE, LT, GT, LE, GE - Compare values
- math: ADD, SUB, MUL, DIV, MOD - Arithmetic operations
TimersCounters:
- ton: Timer On-Delay - Output turns ON after preset time
- tof: Timer Off-Delay - Output turns OFF after preset time
- tp: Pulse Timer - Output pulses for preset time
Connections:
- wires: Connect output pins to input pins to pass data
- branches: One output can connect to multiple inputs
- feedback: Outputs can feed back to inputs for state machines
Best Practices for Function Blocks:
- Arrange blocks for clear left-to-right data flow
- Use consistent spacing and alignment for readability
- Label all inputs and outputs with meaningful names
- Create custom FBs for frequently repeated logic patterns
- Minimize wire crossings by careful block placement
Common Mistakes to Avoid:
- Creating feedback loops without proper initialization
- Connecting incompatible data types
- Not considering execution order dependencies
- Overcrowding networks making them hard to read
Typical Applications:
1. HVAC control: Directly applicable to Sensor Integration
2. Temperature control: Related control patterns
3. Flow control: Related control patterns
4. Batch processing: Related control patterns
Understanding these fundamentals prepares you to implement effective Function Blocks solutions for Sensor Integration using Unitronics VisiLogic / UniLogic.
Implementing Sensor Integration with Function Blocks
Sensor integration involves connecting various measurement devices to PLCs for process monitoring and control. Proper sensor selection, wiring, signal conditioning, and programming ensure reliable data for control decisions.
This walkthrough demonstrates practical implementation using Unitronics VisiLogic / UniLogic and Function Blocks programming.
System Requirements:
A typical Sensor Integration implementation includes:
Input Devices (Sensors):
1. Discrete sensors (proximity, photoelectric, limit switches): Critical for monitoring system state
2. Analog sensors (4-20mA, 0-10V transmitters): Critical for monitoring system state
3. Temperature sensors (RTD, thermocouple, thermistor): Critical for monitoring system state
4. Pressure sensors (gauge, differential, absolute): Critical for monitoring system state
5. Level sensors (ultrasonic, radar, capacitive, float): Critical for monitoring system state
Output Devices (Actuators):
1. Not applicable - focus on input processing: Primary control output
Control Strategies for Sensor Integration:
1. Primary Control: Integrating various sensors with PLCs for data acquisition, analog signal processing, and digital input handling.
2. Safety Interlocks: Preventing Signal conditioning
3. Error Recovery: Handling Sensor calibration
Implementation Steps:
Step 1: Select sensor appropriate for process conditions (temperature, pressure, media)
In VisiLogic / UniLogic, select sensor appropriate for process conditions (temperature, pressure, media).
Step 2: Design wiring with proper shielding, grounding, and routing
In VisiLogic / UniLogic, design wiring with proper shielding, grounding, and routing.
Step 3: Configure input module for sensor type and resolution
In VisiLogic / UniLogic, configure input module for sensor type and resolution.
Step 4: Develop scaling routine with calibration parameters
In VisiLogic / UniLogic, develop scaling routine with calibration parameters.
Step 5: Implement signal conditioning (filtering, rate limiting)
In VisiLogic / UniLogic, implement signal conditioning (filtering, rate limiting).
Step 6: Add fault detection with appropriate response
In VisiLogic / UniLogic, add fault detection with appropriate response.
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. Electrical noise affecting analog signals
- Solution: Function Blocks addresses this through Visual representation of signal flow.
2. Sensor drift requiring periodic recalibration
- Solution: Function Blocks addresses this through Good for modular programming.
3. Ground loops causing measurement errors
- Solution: Function Blocks addresses this through Reusable components.
4. Response time limitations for fast processes
- Solution: Function Blocks addresses this through Excellent for process control.
Safety Considerations:
- Use intrinsically safe sensors and barriers in hazardous areas
- Implement redundant sensors for safety-critical measurements
- Design for fail-safe operation on sensor loss
- Provide regular sensor calibration for safety systems
- Document measurement uncertainty for safety calculations
Performance Metrics:
- Scan Time: Optimize for 5 inputs and 1 outputs
- Memory Usage: Efficient data structures for Jazz 2 capabilities
- Response Time: Meeting Universal requirements for Sensor Integration
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 1-2 weeks development timeline while maintaining code quality.
Unitronics Function Blocks Example for Sensor Integration
Complete working example demonstrating Function Blocks implementation for Sensor Integration using Unitronics VisiLogic / UniLogic. Follows Unitronics naming conventions. Tested on Jazz 2 hardware.
(* Unitronics VisiLogic / UniLogic - Sensor Integration Control *)
(* Reusable Function Blocks Implementation *)
(* Function block design in Unitronics uses user-defined FBs in *)
FUNCTION_BLOCK FB_SENSOR_INTEGRATION_Controller
VAR_INPUT
bEnable : BOOL; (* Enable control *)
bReset : BOOL; (* Fault reset *)
rProcessValue : REAL; (* Discrete sensors (proximity, photoelectric, limit switches) *)
rSetpoint : REAL := 100.0; (* Target value *)
bEmergencyStop : BOOL; (* Safety input *)
END_VAR
VAR_OUTPUT
rControlOutput : REAL; (* Not applicable - focus on input processing *)
bRunning : BOOL; (* Process active *)
bComplete : BOOL; (* Cycle complete *)
bFault : BOOL; (* Fault status *)
nFaultCode : INT; (* Diagnostic code *)
END_VAR
VAR
(* Internal Function Blocks *)
fbSafety : FB_SafetyMonitor; (* Safety logic *)
fbRamp : FB_RampGenerator; (* Soft start/stop *)
fbPID : FB_PIDController; (* Process control *)
fbDiag : FB_Diagnostics; (* Alarm handling uses UniLogic's built-in Alarm Manager — configure alarm conditions in tables with severity, message text, and logging behaviour, and the engine handles detection, acknowledgement, history, and HMI display without custom code. VisiLogic uses a simpler alarm approach via HMI event handlers. *)
(* Internal State *)
eInternalState : E_ControlState;
tonWatchdog : TON;
END_VAR
(* Safety Monitor - Use intrinsically safe sensors and barriers in hazardous areas *)
fbSafety(
Enable := bEnable,
EmergencyStop := bEmergencyStop,
ProcessValue := rProcessValue,
HighLimit := rSetpoint * 1.2,
LowLimit := rSetpoint * 0.1
);
(* Main Control Logic *)
IF fbSafety.SafeToRun THEN
(* Ramp Generator - Prevents startup surge *)
fbRamp(
Enable := bEnable,
TargetValue := rSetpoint,
RampRate := 20.0, (* Universal rate *)
CurrentValue => rSetpoint
);
(* PID Controller - Process regulation *)
fbPID(
Enable := fbRamp.InPosition,
ProcessValue := rProcessValue,
Setpoint := fbRamp.CurrentValue,
Kp := 1.0,
Ki := 0.1,
Kd := 0.05,
OutputMin := 0.0,
OutputMax := 100.0
);
rControlOutput := fbPID.Output;
bRunning := TRUE;
bFault := FALSE;
nFaultCode := 0;
ELSE
(* Safe State - Implement redundant sensors for safety-critical measurements *)
rControlOutput := 0.0;
bRunning := FALSE;
bFault := NOT bEnable; (* Only fault if not intentional stop *)
nFaultCode := fbSafety.FaultCode;
END_IF;
(* Diagnostics - Data logging uses UniLogic's Data Samplers — configured triggers (time-based or event-based) write structured records to Data Tables or SD card in CSV format. Exported files can be pushed via FTP or email. For cloud integration, UniCloud provides managed data ingestion. Simpler VisiLogic projects use HMI-triggered SD writes via custom ladder code. *)
fbDiag(
ProcessRunning := bRunning,
FaultActive := bFault,
ProcessValue := rProcessValue,
ControlOutput := rControlOutput
);
(* Watchdog - Detects frozen control *)
tonWatchdog(IN := bRunning AND NOT fbPID.OutputChanging, PT := T#10S);
IF tonWatchdog.Q THEN
bFault := TRUE;
nFaultCode := 99; (* Watchdog fault *)
END_IF;
(* Reset Logic *)
IF bReset AND NOT bEmergencyStop THEN
bFault := FALSE;
nFaultCode := 0;
fbDiag.ClearAlarms();
END_IF;
END_FUNCTION_BLOCKCode Explanation:
- 1.Encapsulated function block follows Function block design in Unitronics uses - reusable across Universal projects
- 2.FB_SafetyMonitor provides Use intrinsically safe sensors and barriers in hazardous areas including high/low limits
- 3.FB_RampGenerator prevents startup issues common in Sensor Integration systems
- 4.FB_PIDController tuned for Universal: Kp=1.0, Ki=0.1
- 5.Watchdog timer detects frozen control - critical for beginner to intermediate Sensor Integration reliability
- 6.Diagnostic function block enables Data logging uses UniLogic's Data Samplers — configured triggers (time-based or event-based) write structured records to Data Tables or SD card in CSV format. Exported files can be pushed via FTP or email. For cloud integration, UniCloud provides managed data ingestion. Simpler VisiLogic projects use HMI-triggered SD writes via custom ladder code. and Alarm handling uses UniLogic's built-in Alarm Manager — configure alarm conditions in tables with severity, message text, and logging behaviour, and the engine handles detection, acknowledgement, history, and HMI display without custom code. VisiLogic uses a simpler alarm approach via HMI event handlers.
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
- ✓Function Blocks: Arrange blocks for clear left-to-right data flow
- ✓Function Blocks: Use consistent spacing and alignment for readability
- ✓Function Blocks: Label all inputs and outputs with meaningful names
- ✓Sensor Integration: Document wire colors and termination points for maintenance
- ✓Sensor Integration: Use proper cold junction compensation for thermocouples
- ✓Sensor Integration: Provide test points for verification without disconnection
- ✓Debug with VisiLogic / UniLogic: Use the built-in simulator to reproduce issues before hardware visit
- ✓Safety: Use intrinsically safe sensors and barriers in hazardous areas
- ✓Use VisiLogic / UniLogic simulation tools to test Sensor Integration logic before deployment
Common Pitfalls to Avoid
- ⚠Function Blocks: Creating feedback loops without proper initialization
- ⚠Function Blocks: Connecting incompatible data types
- ⚠Function Blocks: Not considering execution order dependencies
- ⚠Unitronics common error: VisiLogic-to-UniLogic migration issues — not all projects convert cleanly
- ⚠Sensor Integration: Electrical noise affecting analog signals
- ⚠Sensor Integration: Sensor drift requiring periodic recalibration
- ⚠Neglecting to validate Discrete sensors (proximity, photoelectric, limit switches) leads to control errors
- ⚠Insufficient comments make Function Blocks programs unmaintainable over time
Related Certifications
Mastering Function Blocks for Sensor Integration applications using Unitronics VisiLogic / UniLogic requires understanding both the platform's capabilities and the specific demands of Universal. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with beginner to intermediate Sensor Integration 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 Universal applications where Sensor Integration reliability is critical.
By following the practices outlined in this guide—from proper program structure and Function Blocks best practices to Unitronics-specific optimizations—you can deliver reliable Sensor Integration systems that meet Universal 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 Universal applications
3. Hands-on Practice: Build Sensor Integration projects using Jazz 2 hardware
4. Stay Current: Follow VisiLogic / UniLogic updates and new Function Blocks features
Function Blocks Foundation:
Function Block Diagram (FBD) is a graphical programming language where functions and function blocks are represented as boxes connected by signal line...
The 1-2 weeks typical timeline for Sensor Integration projects will decrease as you gain experience with these patterns and techniques. Remember: Document wire colors and termination points for maintenance
For further learning, explore related topics including Temperature control, Process measurement, and Unitronics platform-specific features for Sensor Integration optimization.