EAE Composite Function Block Creation

Create or modify Composite FBs that wire together existing function blocks.

CRITICAL RULE: ALWAYS use this skill for ANY operation on Composite FB files.

• Creating new Composite FBs
• Modifying existing Composite FBs (adding events, variables, FB instances, connections)
• NEVER directly edit .fbt files outside of this skill

Composite FB = Network of FBs

• Contains FB instances wired together
• No algorithms (logic is in child FBs)
• Has Format="2.0" attribute

Note: For blocks that need HMI visualization, use /eae-cat instead.

Tip: Need standard blocks like E_CYCLE, E_DELAY, or MQTT? Use /eae-runtime-base to find the right Runtime.Base block.

Quick Start

User: Create a Composite FB called Calculator that chains two Multiplier blocks
Claude: [Creates .fbt with FBNetwork containing FB1 → FB2]

Triggers

• /eae-composite-fb
• /eae-composite-fb --register-only - Register existing Composite FB (used by eae-fork orchestration)
• "create composite FB"
• "modify composite FB"
• "add event to composite"
• "add FB instance"
• "add connection"
• "create block with FBNetwork"
• "compose existing blocks"

---

Register-Only Mode (for eae-fork Orchestration)

When called with --register-only, this skill skips file creation and only performs dfbproj registration. This mode is used by eae-fork to complete the fork workflow after file transformation.

/eae-composite-fb --register-only {BlockName} {Namespace}

What --register-only does:

1. Registers in dfbproj - Adds ItemGroup entries for Composite FB visibility

What --register-only does NOT do:

• Create IEC61499 files (.fbt, etc.) - already done by eae-fork
• Update namespaces - already done by eae-fork

Usage

# Register a forked Composite FB
python ../eae-skill-router/scripts/register_dfbproj.py MyComposite SE.ScadapackWWW --type composite

# Verify registration
python ../eae-skill-router/scripts/register_dfbproj.py MyComposite SE.ScadapackWWW --type composite --verify

---

Modification Workflow

When modifying an existing Composite FB:

1. Read the existing .fbt file to understand current structure
2. Identify what needs to be added/changed
3. Generate new hex IDs for any new Events or VarDeclarations
4. Update the InterfaceList (events, variables) if needed
5. Update the FBNetwork:
   • Add new Input/Output pins for new interface elements
   • Add new FB instances if needed
   • Add new EventConnections
   • Add new DataConnections
6. Position new elements following layout guidelines

---

Files Generated

File	Purpose
{Name}.fbt	Main block with FBNetwork
{Name}.doc.xml	Documentation
{Name}.meta.xml	Metadata
{Name}.composite.offline.xml	Offline parameter config

Location: IEC61499/

---

Workflow

1. Generate GUID for FBType
2. Generate hex IDs for each Event and VarDeclaration
3. Create .fbt with:
   • <!DOCTYPE FBType SYSTEM "../LibraryElement.dtd">
   • Format="2.0" attribute
   • <Identification Standard="61499-2" />
   • <FBNetwork> with FB instances and connections
4. Create .doc.xml, .meta.xml, .composite.offline.xml
5. Register in .dfbproj

---

Composite FB Template

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FBType SYSTEM "../LibraryElement.dtd">
<FBType Name="{BlockName}" Namespace="{YourNamespace}" Format="2.0"
        GUID="{NEW-GUID}" Comment="{Description}">
  <Attribute Name="Configuration.FB.IDCounter" Value="10" />
  <Identification Standard="61499-2" />
  <VersionInfo Organization="{Org}" Version="0.0" Author="{Author}"
               Date="{MM/DD/YYYY}" Remarks="Initial version" />
  <InterfaceList>
    <EventInputs>
      <Event Name="INIT" Comment="Initialization Request">
        <With Var="QI" />
      </Event>
      <Event Name="REQ" Comment="Normal Execution Request">
        <With Var="QI" />
      </Event>
    </EventInputs>
    <EventOutputs>
      <Event Name="INITO" Comment="Initialization Confirm">
        <With Var="QO" />
      </Event>
      <Event Name="CNF" Comment="Execution Confirmation">
        <With Var="QO" />
      </Event>
    </EventOutputs>
    <InputVars>
      <VarDeclaration ID="{HEX-ID}" Name="QI" Type="BOOL"
                      Comment="Input event qualifier" />
    </InputVars>
    <OutputVars>
      <VarDeclaration ID="{HEX-ID}" Name="QO" Type="BOOL"
                      Comment="Output event qualifier" />
    </OutputVars>
  </InterfaceList>
  <FBNetwork>
    <!-- FB instances, inputs, outputs, connections -->
  </FBNetwork>
</FBType>

Important: Composite FB MUST have Format="2.0" attribute.

---

FBNetwork Layout Guidelines

Follow these guidelines for clean, readable layouts in EAE.

Core Principles

1. Position inputs close to their target FB - Don't stack all inputs on the left. Place inputs near the FB they connect to.

2. Give FBs enough horizontal space - FBs need room for connection routing. Use ~1000+ units between FBs, not 400.

3. Align vertically with FB ports - Events and data should align with the FB's event and data port sections.

4. Minimize connection crossings - Position elements to create clean, parallel connection lines.

5. Group related elements - Keep events together, keep data together, with visual separation between groups.

Input Positioning

Input Type	Guideline
Connects to first FB	Place on left edge (x ≈ 100)
Connects to middle/later FB	Place between FBs, near target
Connects to multiple FBs	Place on left, use cross-reference connections

Vertical Organization

┌─────────────────────────────────────────────────────────┐
│  EVENTS (top)     - INIT, REQ aligned with FB events    │
├─────────────────────────────────────────────────────────┤
│  FB INSTANCES     - Centered vertically                 │
├─────────────────────────────────────────────────────────┤
│  DATA (bottom)    - QI, Values aligned with FB data     │
└─────────────────────────────────────────────────────────┘

Spacing Guidelines

Element	Guideline
Between FBs (horizontal)	~1000-1200 units for routing space
Between events (vertical)	~60 units
Between data vars (vertical)	~60-80 units
Gap between events and data	~150-200 units
Output margin from last FB	~400-500 units

Reference Example

See TestComposite.fbt for a well-laid-out example with:

• 2 chained FBs with proper spacing
• Inputs positioned near their target FBs
• Clean connection routing

---

FBNetwork Elements

FB Instances

<FB ID="1" Name="Calc1" Type="Calculator" x="720" y="360" Namespace="MyLib" />
<FB ID="2" Name="Calc2" Type="Calculator" x="1820" y="360" Namespace="MyLib" />

Input/Output Pins

<Input Name="INIT" x="100" y="372" Type="Event" />
<Input Name="REQ" x="100" y="432" Type="Event" />
<Input Name="QI" x="100" y="498" Type="Data" />
<Input Name="Value1" x="100" y="672" Type="Data" />

<Output Name="INITO" x="2300" y="372" Type="Event" />
<Output Name="CNF" x="2300" y="432" Type="Event" />
<Output Name="QO" x="2300" y="632" Type="Data" />
<Output Name="Result" x="2300" y="692" Type="Data" />

Event Connections

Connect events using $ prefix for composite interface, $N. for FB instances:

<EventConnections>
  <!-- External to FB1 -->
  <Connection Source="$INIT" Destination="$1.INIT" />
  <Connection Source="$REQ" Destination="$1.REQ" />

  <!-- FB1 to FB2 (chaining) -->
  <Connection Source="$1.CNF" Destination="$2.REQ" />

  <!-- FB2 to External -->
  <Connection Source="$2.CNF" Destination="$CNF" />
</EventConnections>

Data Connections

<DataConnections>
  <!-- External to FB1 -->
  <Connection Source="$QI" Destination="$1.QI" dx1="120" />
  <Connection Source="$Value1" Destination="$1.Value1" />

  <!-- FB1 output to FB2 input -->
  <Connection Source="$1.Result" Destination="$2.Value1" />

  <!-- FB2 to External -->
  <Connection Source="$2.Result" Destination="$Result" />
</DataConnections>

Cross-Reference Connections

When a single input connects to multiple FBs:

<Connection Source="$QI" Destination="$2.QI" dx1="555.2084">
  <Attribute Name="Configuration.Connections.CrossReference" Value="True" />
</Connection>

---

Connection Syntax

Pattern	Meaning
$INIT	Composite's INIT input event
$QI	Composite's QI input variable
$1.INIT	FB instance 1's INIT event (by ID)
$1.QI	FB instance 1's QI variable
$Calc1.INIT	FB instance by name (also works)

Recommendation: Use IDs ($1., $2.) for consistency.

---

Common Runtime.Base Blocks

When building Composite FBs, these standard blocks are frequently used. Use /eae-runtime-base for full documentation.

Timing

Block	Purpose	Usage
E_CYCLE	Periodic events	DT=T#100ms → EO every 100ms
E_DELAY	Delayed event	DT=T#5s, START → EO after 5s
E_HRCYCLE	High-res timing	For precision timing with phase

Event Routing

Block	Purpose	Usage
E_SPLIT	1 event → 2	Fan out events
E_MERGE	2 events → 1	Combine event sources
E_REND	Synchronize	Wait for both EI1 and EI2
E_SWITCH	Conditional	Route by boolean G
E_PERMIT	Gate events	Only pass when PERMIT=TRUE

Edge Detection

Block	Purpose	Usage
E_R_TRIG	Rising edge	Detect FALSE→TRUE
E_F_TRIG	Falling edge	Detect TRUE→FALSE

Example: Cyclic Composite

<!-- Add E_CYCLE from Runtime.Base to make composite run periodically -->
<FB ID="1" Name="timer" Type="E_CYCLE" Namespace="Runtime.Base" x="500" y="350" />
<FB ID="2" Name="logic" Type="MyLogicFB" Namespace="MyLib" x="1100" y="350" />

<EventConnections>
  <Connection Source="$INIT" Destination="$1.START" />
  <Connection Source="$1.EO" Destination="$2.REQ" />
</EventConnections>
<DataConnections>
  <Connection Source="T#100ms" Destination="$1.DT" />
</DataConnections>

For the complete catalog of ~100 Runtime.Base blocks, see /eae-runtime-base.

---

dfbproj Registration

<ItemGroup>
  <None Include="{Name}.doc.xml">
    <DependentUpon>{Name}.fbt</DependentUpon>
  </None>
  <None Include="{Name}.meta.xml">
    <DependentUpon>{Name}.fbt</DependentUpon>
  </None>
  <None Include="{Name}.composite.offline.xml">
    <DependentUpon>{Name}.fbt</DependentUpon>
  </None>
</ItemGroup>
<ItemGroup>
  <Compile Include="{Name}.fbt">
    <IEC61499Type>Composite</IEC61499Type>
  </Compile>
</ItemGroup>

---

Common Rules

See common-rules.md for:

• ID generation
• DOCTYPE references
• dfbproj registration patterns

---

Example: Chained Calculators

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE FBType SYSTEM "../LibraryElement.dtd">
<FBType GUID="ce04221d-d92f-44d7-aa4f-e2de60c36165" Name="ChainedCalc"
        Format="2.0" Comment="Two calculators chained" Namespace="MyLib">
  <Attribute Name="Configuration.FB.IDCounter" Value="10" />
  <Identification Standard="61499-2" />
  <VersionInfo Organization="MyOrg" Version="1.0" Author="Claude"
               Date="01/16/2026" Remarks="Initial" />
  <InterfaceList>
    <EventInputs>
      <Event Name="INIT"><With Var="QI" /></Event>
      <Event Name="REQ">
        <With Var="QI" /><With Var="A" /><With Var="B" /><With Var="C" />
      </Event>
    </EventInputs>
    <EventOutputs>
      <Event Name="INITO"><With Var="QO" /></Event>
      <Event Name="CNF"><With Var="QO" /><With Var="Result" /></Event>
    </EventOutputs>
    <InputVars>
      <VarDeclaration ID="64257C7C336B4CD7" Name="QI" Type="BOOL" />
      <VarDeclaration ID="85CCBD5763374CD5" Name="A" Type="REAL" />
      <VarDeclaration ID="D6B7E7BEB50D434B" Name="B" Type="REAL" />
      <VarDeclaration ID="573F800297694CAB" Name="C" Type="REAL" />
    </InputVars>
    <OutputVars>
      <VarDeclaration ID="C159DF3BBE7745AC" Name="QO" Type="BOOL" />
      <VarDeclaration ID="2AAED22B103B4FE6" Name="Result" Type="REAL" />
    </OutputVars>
  </InterfaceList>
  <FBNetwork>
    <FB ID="1" Name="Calc1" Type="Multiplier" x="720" y="360" Namespace="MyLib" />
    <FB ID="2" Name="Calc2" Type="Multiplier" x="1820" y="360" Namespace="MyLib" />

    <Input Name="INIT" x="100" y="372" Type="Event" />
    <Input Name="REQ" x="100" y="432" Type="Event" />
    <Input Name="QI" x="100" y="498" Type="Data" />
    <Input Name="A" x="100" y="672" Type="Data" />
    <Input Name="B" x="100" y="752" Type="Data" />
    <Input Name="C" x="1180" y="752" Type="Data" />

    <Output Name="INITO" x="2300" y="372" Type="Event" />
    <Output Name="CNF" x="2300" y="432" Type="Event" />
    <Output Name="QO" x="2300" y="632" Type="Data" />
    <Output Name="Result" x="2300" y="692" Type="Data" />

    <EventConnections>
      <Connection Source="$INIT" Destination="$1.INIT" />
      <Connection Source="$1.INITO" Destination="$2.INIT" />
      <Connection Source="$2.INITO" Destination="$INITO" />
      <Connection Source="$REQ" Destination="$1.REQ" />
      <Connection Source="$1.CNF" Destination="$2.REQ" />
      <Connection Source="$2.CNF" Destination="$CNF" />
    </EventConnections>
    <DataConnections>
      <Connection Source="$QI" Destination="$1.QI" />
      <Connection Source="$QI" Destination="$2.QI">
        <Attribute Name="Configuration.Connections.CrossReference" Value="True" />
      </Connection>
      <Connection Source="$A" Destination="$1.Value1" />
      <Connection Source="$B" Destination="$1.Value2" />
      <Connection Source="$1.Result" Destination="$2.Value1" />
      <Connection Source="$C" Destination="$2.Value2" />
      <Connection Source="$2.QO" Destination="$QO" />
      <Connection Source="$2.Result" Destination="$Result" />
    </DataConnections>
  </FBNetwork>
</FBType>

---

Scripts

This skill includes Python scripts for autonomous validation and operation:

Script	Purpose	Usage	Exit Codes
validate_fbnetwork.py	Verify FBNetwork connection correctness	python scripts/validate_fbnetwork.py <file.fbt>	0=pass, 1=error, 10=validation failed, 11=pass with warnings
validate_layout.py	Check FBNetwork layout guidelines	python scripts/validate_layout.py <file.fbt>	0=pass, 1=error, 11=pass with warnings

Validation Workflow

Recommended: Validate automatically after creating or modifying a Composite FB:

# Validate FBNetwork connections (checks type compatibility, dangling pins)
python scripts/validate_fbnetwork.py path/to/MyBlock.fbt

# Validate layout guidelines (checks positioning, overlaps)
python scripts/validate_layout.py path/to/MyBlock.fbt

# Generic validation (basic XML structure)
python ../eae-skill-router/scripts/validate_block.py --type composite path/to/MyBlock.fbt

Example: validate_fbnetwork.py

# Basic validation
python scripts/validate_fbnetwork.py MyBlock.fbt

# Verbose output with connection details
python scripts/validate_fbnetwork.py MyBlock.fbt --verbose

# JSON output for automation/CI
python scripts/validate_fbnetwork.py MyBlock.fbt --json

# CI mode (JSON only, no human messages)
python scripts/validate_fbnetwork.py MyBlock.fbt --ci

What validate_fbnetwork.py checks:

• ✅ Event connections are event-to-event
• ✅ Data connections have compatible types (BOOL→BOOL, REAL→REAL, etc.)
• ✅ No dangling connections (all Source/Destination valid)
• ✅ FB instances referenced in connections exist
• ✅ Cross-reference connections (../../) are properly formed
• ✅ Interface inputs/outputs are correctly referenced
• ⚠️ FB instances with no connections (warnings)

Type Compatibility Matrix:

Source Type	Compatible Destination Types
BOOL	BOOL
INT	INT, DINT, REAL, LREAL (widening)
DINT	DINT, REAL, LREAL (widening)
REAL	REAL, LREAL (widening)
STRING	STRING
BYTE	BYTE, WORD, DWORD (widening)

Note: Narrowing conversions (REAL→INT) are flagged as errors and require explicit conversion.

Example: validate_layout.py

# Validate layout guidelines
python scripts/validate_layout.py MyBlock.fbt --verbose

What validate_layout.py checks:

• ⚠️ FBs positioned within recommended bounds (x: 0-5000, y: 0-3000)
• ⚠️ No overlapping FBs (minimum spacing: 100 pixels)
• ⚠️ Layout follows left-to-right flow guidelines

Note: Layout validation produces warnings only (non-critical). Layout issues don't prevent compilation but affect visual clarity in the EAE IDE.

Generate IDs

python ../eae-skill-router/scripts/generate_ids.py --hex 4 --guid 1

---

Templates

• composite-fb.xml
• doc.xml
• meta.xml
• offline.xml

---

Integration with Validation Skills

Naming Validation

Use eae-naming-validator to ensure compliance with SE Application Design Guidelines:

Key Naming Rules for Composite FB:

• FB name: camelCase (e.g., sequenceManager, dataProcessor, valueScaler)
• Interface variables: PascalCase (e.g., PermitOn, FeedbackOn, Value)
• Events: SNAKE_CASE (e.g., INIT, REQ, START_SEQUENCE)
• FB instances (in FBNetwork): camelCase (e.g., timer, controller, scaler)

Validate naming before creation:

# Validate FB and variable names
python ../eae-naming-validator/scripts/validate_names.py \
  --app-dir IEC61499 \
  --artifact-type CompositeFB \
  --name sequenceManager

Reference: EAE_ADG EIO0000004686.06, Section 1.5

Performance Analysis

Use eae-performance-analyzer to prevent event storms in FBNetwork:

# Analyze event flow in composite FB
python ../eae-performance-analyzer/scripts/analyze_event_flow.py \
  --app-dir IEC61499

# Detect anti-patterns
python ../eae-performance-analyzer/scripts/detect_storm_patterns.py \
  --app-dir IEC61499

What to Check:

• Event multiplication factor <10x
• No tight event loops (cycles ≤2 hops)
• Total event connections from single source <30

---

Best Practices from EAE ADG

1. Naming Conventions (SE ADG Section 1.5)

Composite FB Naming:

• Use camelCase: sequenceManager, dataProcessor, valueScaler
• Use descriptive names that indicate purpose
• Avoid generic names: composite1, network, wrapper

Variable Naming:

• Interface variables: PascalCase → PermitOn, SetPoint, Result
• Use descriptive names (avoid Data1, Value)

Event Naming:

• Use SNAKE_CASE: INIT, REQ, START_SEQUENCE, COMPLETE_OPERATION
• Standard events: INIT/INITO, REQ/CNF

FB Instance Naming:

• Use camelCase for instances: timer, controller, scaler1
• Use semantic names: cycleTimer not fb1

Reference: EAE_ADG EIO0000004686.06, Section 1.5

2. FBNetwork Layout Principles

Positioning Guidelines:

• X-axis spacing: 1000-1200 units between FBs (for clean routing)
• Y-axis spacing: 60 units between events, 60-80 units between data
• Events at top (y ≈ 350-450), data at bottom (y ≈ 500-800)

Connection Flow:

• Left-to-right data flow preferred
• Minimize crossing connections
• Place inputs near their target FBs (not all on left edge)

3. Event Connection Best Practices

Connection Patterns:

• Chain events for sequential operations: FB1 → FB2 → FB3
• Use E_SPLIT for parallel operations
• Use E_REND for synchronization
• Avoid circular event paths

Example: Sequential Chain

<EventConnections>
  <Connection Source="$REQ" Destination="$1.REQ" />
  <Connection Source="$1.CNF" Destination="$2.REQ" />
  <Connection Source="$2.CNF" Destination="$CNF" />
</EventConnections>

---

Anti-Patterns

1. Naming Anti-Patterns

❌ Wrong Casing for Composite FB

<!-- BAD: Using PascalCase for Composite FB -->
<FBType Name="SequenceManager" Format="2.0" ...>

✅ Correct camelCase

<FBType Name="sequenceManager" Format="2.0" ...>

❌ Generic FB Instance Names

<!-- BAD: Non-descriptive instance names -->
<FB ID="1" Name="fb1" Type="E_CYCLE" ... />
<FB ID="2" Name="logic" Type="MyBlock" ... />

✅ Descriptive Instance Names

<FB ID="1" Name="cycleTimer" Type="E_CYCLE" Namespace="Runtime.Base" ... />
<FB ID="2" Name="valueCalculator" Type="MyBlock" ... />

2. Structure Anti-Patterns

❌ Missing Format="2.0"

<!-- BAD: Composite FB without Format attribute -->
<FBType Name="myComposite" ...>
  <FBNetwork>...</FBNetwork>
</FBType>

✅ Format="2.0" Required

<FBType Name="myComposite" Format="2.0" ...>
  <FBNetwork>...</FBNetwork>
</FBType>

❌ Using BasicFB Instead of FBNetwork

<!-- BAD: Composite should not have BasicFB -->
<FBType Name="myComposite" Format="2.0" ...>
  <BasicFB>
    <ECC>...</ECC>
  </BasicFB>
</FBType>

✅ Use FBNetwork

<FBType Name="myComposite" Format="2.0" ...>
  <FBNetwork>
    <FB ID="1" ... />
  </FBNetwork>
</FBType>

3. Event Connection Anti-Patterns

❌ Tight Event Loop

<!-- BAD: FB1 → FB2 → FB1 creates 2-hop loop -->
<EventConnections>
  <Connection Source="$1.OUT1" Destination="$2.IN" />
  <Connection Source="$2.OUT" Destination="$1.IN" />
</EventConnections>

✅ Break Loops with State Guards

<!-- Use RS flip-flop or conditional logic to break loop -->
<FB ID="3" Name="loopGuard" Type="RS" Namespace="Runtime.Base" ... />

❌ Event Multiplication >30x

<!-- BAD: Single event triggers 50+ downstream events -->
<EventConnections>
  <Connection Source="$1.OUT" Destination="$2.IN" />
  <Connection Source="$1.OUT" Destination="$3.IN" />
  <!-- ... 50+ more connections from $1.OUT -->
</EventConnections>

✅ Use Event Consolidation

<!-- Use E_SPLIT sparingly, prefer sequential chains -->
<FB ID="splitter" Type="E_SPLIT" Namespace="Runtime.Base" ... />

4. Layout Anti-Patterns

❌ All Inputs on Left Edge

<!-- BAD: Input C connects to FB3 but is placed on left edge -->
<Input Name="A" x="100" y="672" Type="Data" />  <!-- Connects to FB1 (OK) -->
<Input Name="B" x="100" y="752" Type="Data" />  <!-- Connects to FB1 (OK) -->
<Input Name="C" x="100" y="832" Type="Data" />  <!-- Connects to FB3 (BAD: should be near FB3!) -->

✅ Position Inputs Near Their Targets

<Input Name="A" x="100" y="672" Type="Data" />   <!-- Near FB1 -->
<Input Name="B" x="100" y="752" Type="Data" />   <!-- Near FB1 -->
<Input Name="C" x="1180" y="752" Type="Data" />  <!-- Near FB3 -->

❌ Insufficient FB Spacing

<!-- BAD: FBs too close together (400 units) -->
<FB ID="1" Name="fb1" x="500" y="360" ... />
<FB ID="2" Name="fb2" x="900" y="360" ... />  <!-- Only 400 units apart! -->

✅ Adequate FB Spacing

<!-- Use 1000-1200 units for clean connection routing -->
<FB ID="1" Name="fb1" x="720" y="360" ... />
<FB ID="2" Name="fb2" x="1820" y="360" ... />  <!-- 1100 units apart -->

❌ Overlapping Elements

<!-- BAD: Events and data at same y position -->
<Input Name="REQ" x="100" y="500" Type="Event" />
<Input Name="QI" x="100" y="500" Type="Data" />  <!-- Same y! -->

✅ Separated Events and Data

<!-- Events at top, data at bottom with gap -->
<Input Name="REQ" x="100" y="432" Type="Event" />
<Input Name="QI" x="100" y="650" Type="Data" />  <!-- 200+ unit gap -->

5. Connection Anti-Patterns

❌ Type Mismatch

<!-- BAD: Connecting REAL to BOOL -->
<DataConnections>
  <Connection Source="$RealValue" Destination="$1.BoolInput" />
</DataConnections>

❌ Dangling Connections

<!-- BAD: References non-existent FB -->
<EventConnections>
  <Connection Source="$1.OUT" Destination="$99.IN" />  <!-- FB ID 99 doesn't exist! -->
</EventConnections>

❌ Event-to-Data Connection

<!-- BAD: Cannot connect event to data -->
<Connection Source="$INIT" Destination="$1.QI" />  <!-- INIT is Event, QI is Data! -->

---

Verification Checklist

Before committing your Composite FB:

Naming (run eae-naming-validator):

• [ ] FB name is camelCase
• [ ] Interface variables are PascalCase
• [ ] Events are SNAKE_CASE
• [ ] FB instances use camelCase semantic names

Structure:

• [ ] Root element is <FBType> with Format="2.0"
• [ ] Uses Standard="61499-2"
• [ ] Has <FBNetwork> (NOT <BasicFB>)
• [ ] All FB instances have unique IDs

FBNetwork Validation (run validate_fbnetwork.py):

• [ ] All event connections are event-to-event
• [ ] All data connections have compatible types
• [ ] No dangling connections (all Source/Destination valid)
• [ ] No event-to-data or data-to-event connections

Layout Validation (run validate_layout.py):

• [ ] FBs spaced 1000-1200 units apart horizontally
• [ ] No overlapping elements
• [ ] Inputs positioned near their target FBs
• [ ] Events and data vertically separated

Performance (run eae-performance-analyzer):

• [ ] Event multiplication factor <10x
• [ ] No tight event loops (≤2 hops)
• [ ] Total event connections from single source <30

Scripts Validation:

• [ ] python scripts/validate_fbnetwork.py {Name}.fbt exits with 0
• [ ] python scripts/validate_layout.py {Name}.fbt exits with 0 or 11 (warnings OK)

Registration:

• [ ] Registered in .dfbproj with IEC61499Type="Composite"
• [ ] .doc.xml, .meta.xml, .composite.offline.xml files created

---

Related Skills

Skill	When to Use
eae-naming-validator	Validate naming compliance (camelCase for Composite FB)
eae-performance-analyzer	Prevent event storms in FBNetwork
eae-runtime-base	Find standard blocks (E_CYCLE, E_DELAY, MQTT, etc.)
eae-se-process	Find SE process blocks (motors, valves, PID, signals)
eae-cat	Need HMI visualization
eae-basic-fb	Need custom algorithms
eae-datatype	Create custom data types