kkelomatic_home/docs/redesign/fb_switch-documentation.md

fb_switch Function Block Documentation

Overview

The fb_switch function block is the core control logic for managing lighting in each room. It processes switch inputs from Node-RED and generates light control outputs.

Function Block Structure

FUNCTION_BLOCK fb_switch
VAR_INPUT
    switches: struct_switches;  // Switch states received from Node-RED
END_VAR
VAR_OUTPUT
    lights: struct_lights;      // Light control outputs sent to Node-RED
END_VAR
VAR
    all_off: fb_toogleButton;   // Toggle button for "all off" command
    all_on: fb_toogleButton;    // Toggle button for "all on" command
    sw_1: fb_toogleButton;      // Toggle button for switch 1
    sw_2: fb_toogleButton;      // Toggle button for switch 2
    sw_3: fb_toogleButton;      // Toggle button for switch 3
    sw_4: fb_toogleButton;      // Toggle button for switch 4
    sw_5: fb_toogleButton;      // Toggle button for switch 5
    sw_6: fb_toogleButton;      // Toggle button for switch 6
END_VAR

Data Structures

struct_switches (Input)

TYPE struct_switches :
STRUCT
    all_off: BOOL;  // Command to turn all lights off
    all_on: BOOL;   // Command to turn all lights on
    sw_1: BOOL;     // Switch 1 state
    sw_2: BOOL;     // Switch 2 state
    sw_3: BOOL;     // Switch 3 state
    sw_4: BOOL;     // Switch 4 state
    sw_5: BOOL;     // Switch 5 state
    sw_6: BOOL;     // Switch 6 state
END_STRUCT
END_TYPE

struct_lights (Output)

TYPE struct_lights:
STRUCT
    l_1: BOOL;  // Light 1 control output
    l_2: BOOL;  // Light 2 control output
    l_3: BOOL;  // Light 3 control output
    l_4: BOOL;  // Light 4 control output
    l_5: BOOL;  // Light 5 control output
    l_6: BOOL;  // Light 6 control output
END_STRUCT
END_TYPE

Functionality

Individual Switch Control

Each switch (sw_1 through sw_6) is processed by a fb_toogleButton instance:

• Input: Switch state from switches.sw_X (received from Node-RED)
• Output: Light control to lights.l_X (sent to Node-RED)
• Behavior: Toggle functionality - each switch press toggles the corresponding light state

Global Commands

1. All Off (switches.all_off):

   • When activated, turns off all lights (l_1 through l_6)
   • Uses fb_toogleButton instance all_off

2. All On (switches.all_on):

   • When activated, turns on all lights (l_1 through l_6)
   • Uses fb_toogleButton instance all_on
   • Logic uses AND gates to combine with individual switch states

Logic Flow

1. Switch Input Processing:

   • Each sw_X input is fed to its corresponding fb_toogleButton instance
   • The toggle button processes the input and generates an output

2. Light Output Generation:

   • Individual switch outputs directly control their corresponding lights
   • all_off command can override individual controls
   • all_on command combines with individual switch states using AND logic

3. Output Assignment:

   • sw_1 → lights.l_1
   • sw_2 → lights.l_2
   • sw_3 → lights.l_3
   • sw_4 → lights.l_4
   • sw_5 → lights.l_5
   • sw_6 → lights.l_6

fb_toogleButton Function Block

The fb_toogleButton is a toggle button implementation with debouncing and timing features.

Structure

FUNCTION_BLOCK fb_toogleButton
VAR_INPUT
    Input: BOOL;  // Input signal (switch state)
END_VAR
VAR_OUTPUT
    Output: BOOL; // Output signal (light control)
END_VAR
VAR
    Switch: BOOL;      // Internal switch state
    Light: BOOL;       // Internal light state
    Flag1: BOOL;       // Internal flag 1
    Flag2: BOOL;       // Internal flag 2
    RT: R_TRIG;        // Rising edge trigger
    Pulse: TP;         // Pulse timer
    CTU_0: CTU;        // Counter up 0
    CTD_0: CTD;        // Counter down 0
    CTU_1: CTU;        // Counter up 1
    CTU_2: CTU;        // Counter up 2
    TOF_0: TOF;        // Timer off delay 0
END_VAR

Features

• Rising Edge Detection: Uses R_TRIG to detect switch press events
• Pulse Generation: Uses TP (pulse timer) for debouncing or pulse generation
• Timing Control: Uses TOF (timer off delay) for delayed turn-off
• Counters: Uses CTU and CTD counters for state management
• Toggle Logic: Implements toggle behavior - each press changes state

Behavior

1. Input Processing:

   • Detects rising edge of input signal
   • Generates a pulse for processing
   • Applies timing delays for debouncing

2. State Management:

   • Maintains internal switch and light states
   • Toggles output on each valid input pulse
   • Uses flags for state tracking

3. Output Generation:

   • Output reflects the toggled state
   • May include timing delays (TOF) for smooth operation

Usage in System

Per-Room Instance

Each room has an instance of fb_switch:

• masterBedroom: fb_switch
• masterBathroom: fb_switch
• bedroom_1: fb_switch
• bedroom_2: fb_switch
• bathroom: fb_switch
• guest_wc: fb_switch
• kitchen: fb_switch
• pantry: fb_switch
• livingRoom: fb_switch
• diningRoom: fb_switch
• veranda: fb_switch
• entrance: fb_switch
• front: fb_switch
• back: fb_switch
• side: fb_switch
• hallway: fb_switch

Network Variable Integration

• Input: Receives struct_switches from Node-RED via network variable NVL_Receiver
• Output: Sends struct_lights to Node-RED via network variable NVL_Sender

Control Flow

Node-RED (Zigbee Switch) 
    ↓
MQTT Message
    ↓
Node-RED Processing
    ↓
Network Variable (struct_switches)
    ↓
fb_switch (CODESYS)
    ↓
fb_toogleButton Processing
    ↓
Light Control Output (struct_lights)
    ↓
Network Variable (NVL_Sender)
    ↓
Node-RED
    ↓
EtherCAT Relay Output
    ↓
Physical Light

Notes

• Each room can control up to 6 individual lights
• Global commands (all_on, all_off) provide room-level control
• Toggle button implementation includes debouncing to prevent rapid switching
• Timing functions ensure smooth operation and prevent electrical issues
• The system supports both individual light control and group control per room

---

Documentation Date: January 27, 2026
Sources:

• Home_Automation.export (CODESYS XML)
• Home_Automation.xml (PLCopen XML)

Additional Details: See CODESYS XML Analysis for timing characteristics and detailed logic flow extracted from the PLCopen XML format.