Learning to implement Function Blocks for Safety Systems using Delta's WPLSoft / ISPSoft / DIADesigner-AX 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.
Delta has established itself as Strong in Asian, Indian, and SE Asian OEM machinery — packaging, plastics, textiles, HVAC, food processing — and in cost-sensitive water-treatment, irrigation, and small-plant work across Latin America and EMEA, making it a strategic choice for Safety Systems applications. With ~3–4% global, growing global market share and 7 popular PLC families including the DVP-ES2 / EX2 / SS2 (compact entry) and DVP-SX2 / SA2 / SV2 (motion + analogue), Delta provides the robust platform needed for advanced complexity projects like Safety Systems.
The Function Blocks approach is particularly well-suited for Safety Systems 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 Safety Systems, including safety integrity level (sil) compliance and redundancy requirements.
Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on WPLSoft / ISPSoft / DIADesigner-AX, and industry best practices specific to Universal. Whether you're programming your first Safety Systems system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with Delta Function Blocks programming.
Delta WPLSoft / ISPSoft / DIADesigner-AX for Safety Systems
Delta's PLC programming ecosystem is split between two free Windows IDEs: WPLSoft for the legacy DVP-ES2 / EX2 / SS2 / SX2 / SA2 / SV2 / EH3 family, and ISPSoft for newer DVP-SE / SV2 / SX3 models and the AH and AS mid-range series. WPLSoft is a focused ladder-and-IL editor with an offline simulator, online monitoring with rung-state colour, and built-in Modbus RTU / TCP wizards. ISPSoft is IEC 61131-3 oriented — ladder, structured text, function block diagram and SFC — with project-tree organis...
Platform Strengths for Safety Systems:
- Free WPLSoft and ISPSoft IDEs with built-in offline simulator
- Full IEC 61131-3 language coverage on AH / AS / AX series via ISPSoft
- Mitsubishi-FX-style instruction set easing migration on DVP
- Aggressive pricing typically 30–50% below Siemens or Allen-Bradley
Unique ${brand.software} Features:
- Free WPLSoft IDE for DVP series with built-in offline simulator
- Free ISPSoft IDE for AH / AS / DVP-SE with full IEC 61131-3 language coverage
- Mitsubishi-FX-style instruction set easing migration for FX-trained engineers
- Built-in Modbus RTU and Modbus TCP master / slave on most CPUs
Key Capabilities:
The WPLSoft / ISPSoft / DIADesigner-AX environment excels at Safety Systems applications through its free wplsoft and ispsoft ides with built-in offline simulator. This is particularly valuable when working with the 5 sensor types typically found in Safety Systems systems, including Safety light curtains, Emergency stop buttons, Safety door switches.
Control Equipment for Safety Systems:
- Safety PLCs (fail-safe controllers)
- Safety relays (configurable or fixed)
- Safety I/O modules with diagnostics
- Safety network protocols (PROFIsafe, CIP Safety)
Delta's controller families for Safety Systems include:
- DVP-ES2 / EX2 / SS2 (compact entry): Suitable for advanced Safety Systems applications
- DVP-SX2 / SA2 / SV2 (motion + analogue): Suitable for advanced Safety Systems applications
- DVP-SE (Ethernet): Suitable for advanced Safety Systems applications
- DVP-EH3 (legacy high-end): Suitable for advanced Safety Systems applications
Hardware Selection Guidance:
DVP-ES2 / EX2 / SS2 cover compact entry-level for small machines; DVP-SX2 adds analogue I/O; DVP-SA2 / SV2 step up for motion-heavy applications; DVP-SE adds Ethernet; DVP-EH3 is the legacy high-end. For mid-range process and machine control, AS-series (AS218 / AS228 / AS318 / AS332) and AH-series (AH500 modular rack) are preferred. AX-series motion controllers handle EtherCAT-based multi-axis. Se...
Industry Recognition:
Strong in Asian, Indian, and SE Asian OEM machinery — packaging, plastics, textiles, HVAC, food processing — and in cost-sensitive water-treatment, irrigation, and small-plant work across Latin America and EMEA. Tier 2 / Tier 3 component fixturing and ancillary equipment in Asian and Indian automotive supply chains. Limited Tier 1 line-control presence — OEMs typically specify Siemens or Mitsubishi at that tier....
Investment Considerations:
With $ pricing, Delta positions itself in the value segment. For Safety Systems projects requiring advanced skill levels and 4-8 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.
Understanding Function Blocks for Safety Systems
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 Safety Systems:
- Visual representation of signal flow: Critical for Safety Systems when handling advanced control logic
- Good for modular programming: Critical for Safety Systems when handling advanced control logic
- Reusable components: Critical for Safety Systems when handling advanced control logic
- Excellent for process control: Critical for Safety Systems when handling advanced control logic
- Good for continuous operations: Critical for Safety Systems when handling advanced control logic
Why Function Blocks Fits Safety Systems:
Safety Systems systems in Universal typically involve:
- Sensors: Emergency stop buttons (Category 0 or 1 stop), Safety light curtains (Type 2 or Type 4), Safety laser scanners for zone detection
- Actuators: Safety contactors (mirror contact type), Safe torque off (STO) drives, Safety brake modules
- Complexity: Advanced with challenges including Achieving required safety level with practical architecture
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 Safety Systems
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 Safety Systems using Delta WPLSoft / ISPSoft / DIADesigner-AX.
Implementing Safety Systems with Function Blocks
Safety system control uses safety-rated PLCs and components to protect personnel and equipment from hazardous conditions. These systems implement safety functions per IEC 62443 and ISO 13849 standards with redundancy and diagnostics.
This walkthrough demonstrates practical implementation using Delta WPLSoft / ISPSoft / DIADesigner-AX and Function Blocks programming.
System Requirements:
A typical Safety Systems implementation includes:
Input Devices (Sensors):
1. Emergency stop buttons (Category 0 or 1 stop): Critical for monitoring system state
2. Safety light curtains (Type 2 or Type 4): Critical for monitoring system state
3. Safety laser scanners for zone detection: Critical for monitoring system state
4. Safety interlock switches (tongue, hinged, trapped key): Critical for monitoring system state
5. Safety mats and edges: Critical for monitoring system state
Output Devices (Actuators):
1. Safety contactors (mirror contact type): Primary control output
2. Safe torque off (STO) drives: Supporting control function
3. Safety brake modules: Supporting control function
4. Lock-out valve manifolds: Supporting control function
5. Safety relay outputs: Supporting control function
Control Equipment:
- Safety PLCs (fail-safe controllers)
- Safety relays (configurable or fixed)
- Safety I/O modules with diagnostics
- Safety network protocols (PROFIsafe, CIP Safety)
Control Strategies for Safety Systems:
1. Primary Control: Safety-rated PLC programming for personnel protection, emergency stops, and safety interlocks per IEC 61508/61511.
2. Safety Interlocks: Preventing Safety integrity level (SIL) compliance
3. Error Recovery: Handling Redundancy requirements
Implementation Steps:
Step 1: Perform hazard analysis and risk assessment
In WPLSoft / ISPSoft / DIADesigner-AX, perform hazard analysis and risk assessment.
Step 2: Determine required safety level (SIL/PL) for each function
In WPLSoft / ISPSoft / DIADesigner-AX, determine required safety level (sil/pl) for each function.
Step 3: Select certified safety components meeting requirements
In WPLSoft / ISPSoft / DIADesigner-AX, select certified safety components meeting requirements.
Step 4: Design safety circuit architecture per category requirements
In WPLSoft / ISPSoft / DIADesigner-AX, design safety circuit architecture per category requirements.
Step 5: Implement safety logic in certified safety PLC/relay
In WPLSoft / ISPSoft / DIADesigner-AX, implement safety logic in certified safety plc/relay.
Step 6: Add diagnostics and proof test provisions
In WPLSoft / ISPSoft / DIADesigner-AX, add diagnostics and proof test provisions.
Delta Function Design:
WPLSoft P-labels are the primary reuse mechanism on DVP. ISPSoft instance-based function blocks enable proper IEC-style reuse on AH / AS, with library import / export. Delta-supplied motion, communication, and PID FBs ship with the IDE.
Common Challenges and Solutions:
1. Achieving required safety level with practical architecture
- Solution: Function Blocks addresses this through Visual representation of signal flow.
2. Managing nuisance trips while maintaining safety
- Solution: Function Blocks addresses this through Good for modular programming.
3. Integrating safety with production efficiency
- Solution: Function Blocks addresses this through Reusable components.
4. Documenting compliance with multiple standards
- Solution: Function Blocks addresses this through Excellent for process control.
Safety Considerations:
- Use only certified safety components and PLCs
- Implement dual-channel monitoring per category requirements
- Add diagnostic coverage to detect latent faults
- Design for fail-safe operation (de-energize to trip)
- Provide regular proof testing of safety functions
Performance Metrics:
- Scan Time: Optimize for 5 inputs and 4 outputs
- Memory Usage: Efficient data structures for DVP-ES2 / EX2 / SS2 (compact entry) capabilities
- Response Time: Meeting Universal requirements for Safety Systems
Delta Diagnostic Tools:
WPLSoft / ISPSoft online monitor with rung-state colour,Soft-element watch table and tag watch lists,Built-in offline simulator (WPLSoft and ISPSoft),Modbus RTU / TCP communication wizard with diagnostic counters,DIADesigner-AX integrated diagnostics for AX motion projects,M1000-range system flags for CPU and comms diagnostics,Delta distributor support and loaner CPUs in major markets,Delta IA forum and DeltaPLC community for application questions
Delta's WPLSoft / ISPSoft / DIADesigner-AX provides tools for performance monitoring and optimization, essential for achieving the 4-8 weeks development timeline while maintaining code quality.
Delta Function Blocks Example for Safety Systems
Complete working example demonstrating Function Blocks implementation for Safety Systems using Delta WPLSoft / ISPSoft / DIADesigner-AX. Follows Delta naming conventions. Tested on DVP-ES2 / EX2 / SS2 (compact entry) hardware.
(* Delta WPLSoft / ISPSoft / DIADesigner-AX - Safety Systems Control *)
(* Reusable Function Blocks Implementation *)
(* WPLSoft P-labels are the primary reuse mechanism on DVP. ISP *)
FUNCTION_BLOCK FB_SAFETY_SYSTEMS_Controller
VAR_INPUT
bEnable : BOOL; (* Enable control *)
bReset : BOOL; (* Fault reset *)
rProcessValue : REAL; (* Emergency stop buttons (Category 0 or 1 stop) *)
rSetpoint : REAL := 100.0; (* Target value *)
bEmergencyStop : BOOL; (* Safety input *)
END_VAR
VAR_OUTPUT
rControlOutput : REAL; (* Safety contactors (mirror contact type) *)
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; (* M-flag banks latched on fault detection on DVP; ISPSoft on AH / AS allows alarm structures and HMI alarm-banner integration via Delta DOPSoft or third-party HMIs over Modbus TCP. *)
(* Internal State *)
eInternalState : E_ControlState;
tonWatchdog : TON;
END_VAR
(* Safety Monitor - Use only certified safety components and PLCs *)
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 dual-channel monitoring per category requirements *)
rControlOutput := 0.0;
bRunning := FALSE;
bFault := NOT bEnable; (* Only fault if not intentional stop *)
nFaultCode := fbSafety.FaultCode;
END_IF;
(* Diagnostics - PLC-tier logging is uncommon on DVP — logging happens at the HMI tier (DOPSoft, Delta DIAView SCADA) or via Modbus pull from a higher-level historian. AH / AS supports SD-card data logging and on-board CSV export. *)
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 WPLSoft P-labels are the primary reuse m - reusable across Universal projects
- 2.FB_SafetyMonitor provides Use only certified safety components and PLCs including high/low limits
- 3.FB_RampGenerator prevents startup issues common in Safety Systems systems
- 4.FB_PIDController tuned for Universal: Kp=1.0, Ki=0.1
- 5.Watchdog timer detects frozen control - critical for advanced Safety Systems reliability
- 6.Diagnostic function block enables PLC-tier logging is uncommon on DVP — logging happens at the HMI tier (DOPSoft, Delta DIAView SCADA) or via Modbus pull from a higher-level historian. AH / AS supports SD-card data logging and on-board CSV export. and M-flag banks latched on fault detection on DVP; ISPSoft on AH / AS allows alarm structures and HMI alarm-banner integration via Delta DOPSoft or third-party HMIs over Modbus TCP.
Best Practices
- ✓Follow Delta naming conventions: WPLSoft / DVP work is dominated by raw soft-element addressing (X0, Y0, M100, D1
- ✓Delta function design: WPLSoft P-labels are the primary reuse mechanism on DVP. ISPSoft instance-based
- ✓Data organization: DVP has no structured data blocks — D / register banks are documented by range.
- ✓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
- ✓Safety Systems: Keep safety logic simple and auditable
- ✓Safety Systems: Use certified function blocks from safety PLC vendor
- ✓Safety Systems: Implement cross-monitoring between channels
- ✓Debug with WPLSoft / ISPSoft / DIADesigner-AX: Run the offline simulator with forced inputs before live download
- ✓Safety: Use only certified safety components and PLCs
- ✓Use WPLSoft / ISPSoft / DIADesigner-AX simulation tools to test Safety Systems 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
- ⚠Delta common error: Battery-low alarm on legacy DVP-EH causing D-range data loss
- ⚠Safety Systems: Achieving required safety level with practical architecture
- ⚠Safety Systems: Managing nuisance trips while maintaining safety
- ⚠Neglecting to validate Emergency stop buttons (Category 0 or 1 stop) leads to control errors
- ⚠Insufficient comments make Function Blocks programs unmaintainable over time
Related Certifications
Mastering Function Blocks for Safety Systems applications using Delta WPLSoft / ISPSoft / DIADesigner-AX 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 advanced Safety Systems projects.
Delta's ~3–4% global, growing market share and strong in asian, indian, and se asian oem machinery — packaging, plastics, textiles, hvac, food processing — and in cost-sensitive water-treatment, irrigation, and small-plant work across latin america and emea demonstrate the platform's capability for demanding applications. The platform excels in Universal applications where Safety Systems reliability is critical.
By following the practices outlined in this guide—from proper program structure and Function Blocks best practices to Delta-specific optimizations—you can deliver reliable Safety Systems systems that meet Universal requirements.
Next Steps for Professional Development:
1. Certification: Pursue Delta IA Academy distributor-led engineer training to validate your Delta expertise
2. Advanced Training: Consider WPLSoft / ISPSoft course completions for specialized Universal applications
3. Hands-on Practice: Build Safety Systems projects using DVP-ES2 / EX2 / SS2 (compact entry) hardware
4. Stay Current: Follow WPLSoft / ISPSoft / DIADesigner-AX 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 4-8 weeks typical timeline for Safety Systems projects will decrease as you gain experience with these patterns and techniques. Remember: Keep safety logic simple and auditable
For further learning, explore related topics including Temperature control, Emergency stop systems, and Delta platform-specific features for Safety Systems optimization.