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"

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:

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:

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

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

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

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

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

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

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

Input/Output Pins

Event Connections

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

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

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

Data Connections

<Connection Source="$1.Result" Destination="$2.Value1" />

<Connection Source="$2.Result" Destination="$Result" /> </DataConnections>

Cross-Reference Connections

When a single input connects to multiple FBs:

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

<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" />

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" />

&#x3C;Input Name="INIT" x="100" y="372" Type="Event" />
&#x3C;Input Name="REQ" x="100" y="432" Type="Event" />
&#x3C;Input Name="QI" x="100" y="498" Type="Data" />
&#x3C;Input Name="A" x="100" y="672" Type="Data" />
&#x3C;Input Name="B" x="100" y="752" Type="Data" />
&#x3C;Input Name="C" x="1180" y="752" Type="Data" />

&#x3C;Output Name="INITO" x="2300" y="372" Type="Event" />
&#x3C;Output Name="CNF" x="2300" y="432" Type="Event" />
&#x3C;Output Name="QO" x="2300" y="632" Type="Data" />
&#x3C;Output Name="Result" x="2300" y="692" Type="Data" />

&#x3C;EventConnections>
  &#x3C;Connection Source="$INIT" Destination="$1.INIT" />
  &#x3C;Connection Source="$1.INITO" Destination="$2.INIT" />
  &#x3C;Connection Source="$2.INITO" Destination="$INITO" />
  &#x3C;Connection Source="$REQ" Destination="$1.REQ" />
  &#x3C;Connection Source="$1.CNF" Destination="$2.REQ" />
  &#x3C;Connection Source="$2.CNF" Destination="$CNF" />
&#x3C;/EventConnections>
&#x3C;DataConnections>
  &#x3C;Connection Source="$QI" Destination="$1.QI" />
  &#x3C;Connection Source="$QI" Destination="$2.QI">
    &#x3C;Attribute Name="Configuration.Connections.CrossReference" Value="True" />
  &#x3C;/Connection>
  &#x3C;Connection Source="$A" Destination="$1.Value1" />
  &#x3C;Connection Source="$B" Destination="$1.Value2" />
  &#x3C;Connection Source="$1.Result" Destination="$2.Value1" />
  &#x3C;Connection Source="$C" Destination="$2.Value2" />
  &#x3C;Connection Source="$2.QO" Destination="$QO" />
  &#x3C;Connection Source="$2.Result" Destination="$Result" />
&#x3C;/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

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

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)

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

Anti-Patterns

Naming Anti-Patterns

❌ Wrong Casing for Composite FB

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

✅ Correct camelCase

❌ Generic FB Instance Names

<FB ID="1" Name="fb1" Type="E_CYCLE" ... /> <FB ID="2" Name="logic" Type="MyBlock" ... />

✅ Descriptive Instance Names

Structure Anti-Patterns

❌ Missing Format="2.0"

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

✅ Format="2.0" Required

❌ Using BasicFB Instead of FBNetwork

<FBType Name="myComposite" Format="2.0" ...> <BasicFB> <ECC>...</ECC> </BasicFB> </FBType>

✅ Use FBNetwork

Event Connection Anti-Patterns

❌ Tight Event Loop

<EventConnections> <Connection Source="$1.OUT1" Destination="$2.IN" /> <Connection Source="$2.OUT" Destination="$1.IN" /> </EventConnections>

✅ Break Loops with State Guards

<FB ID="3" Name="loopGuard" Type="RS" Namespace="Runtime.Base" ... />

❌ Event Multiplication >30x

<EventConnections> <Connection Source="$1.OUT" Destination="$2.IN" /> <Connection Source="$1.OUT" Destination="$3.IN" />  </EventConnections>

✅ Use Event Consolidation

<FB ID="splitter" Type="E_SPLIT" Namespace="Runtime.Base" ... />

Layout Anti-Patterns

❌ All Inputs on Left Edge

<Input Name="A" x="100" y="672" Type="Data" />  <Input Name="B" x="100" y="752" Type="Data" />  <Input Name="C" x="100" y="832" Type="Data" />

✅ Position Inputs Near Their Targets

❌ Insufficient FB Spacing

<FB ID="1" Name="fb1" x="500" y="360" ... /> <FB ID="2" Name="fb2" x="900" y="360" ... />

✅ Adequate FB Spacing

<FB ID="1" Name="fb1" x="720" y="360" ... /> <FB ID="2" Name="fb2" x="1820" y="360" ... />

❌ Overlapping Elements

<Input Name="REQ" x="100" y="500" Type="Event" /> <Input Name="QI" x="100" y="500" Type="Data" />

✅ Separated Events and Data

<Input Name="REQ" x="100" y="432" Type="Event" /> <Input Name="QI" x="100" y="650" Type="Data" />

Connection Anti-Patterns

❌ Type Mismatch

<DataConnections> <Connection Source="$RealValue" Destination="$1.BoolInput" /> </DataConnections>

❌ Dangling Connections

<EventConnections> <Connection Source="$1.OUT" Destination="$99.IN" />  </EventConnections>

❌ Event-to-Data Connection

<Connection Source="$INIT" Destination="$1.QI" />

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

eae-composite-fb

Safety Notice

Copy this and send it to your AI assistant to learn

Register a forked Composite FB

Verify registration

Validate FBNetwork connections (checks type compatibility, dangling pins)

Validate layout guidelines (checks positioning, overlaps)

Generic validation (basic XML structure)

Basic validation

Verbose output with connection details

JSON output for automation/CI

CI mode (JSON only, no human messages)

Validate layout guidelines

Validate FB and variable names

Analyze event flow in composite FB

Detect anti-patterns

Source Transparency

Related Skills

eae-basic-fb

eae-skill-router

eae-naming-validator