Initial commit: CODESYS tree, integration docs, Node-RED scripts.

PLC application sources (NVL, rooms, boiler), HA/Node-RED integration guide, and NVL patch utilities.

Co-authored-by: Cursor <cursoragent@cursor.com>

codesys-tree/Device/Plc Logic/Application/3.Function Blocks/fb_light.st

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+(* === DECLARATION === *)
+FUNCTION_BLOCK fb_light
+VAR_INPUT
+    // Home Assistant Commands
+    ha_on: BOOL;      // HA command: Turn ON
+    ha_off: BOOL;     // HA command: Turn OFF
+    
+    // Zigbee Switch Input
+    zigbee_sw: BOOL;  // Zigbee switch (edge detected)
+    
+    // Status Feedback
+    relay_status: BOOL;  // Actual relay state (read from EtherCAT)
+END_VAR
+VAR_OUTPUT
+    light_output: BOOL;      // Control output to relay
+    light_status: BOOL;      // Status to send back (actual relay state)
+END_VAR
+VAR
+    // Edge triggers
+    r_trig_ha_on: R_TRIG;
+    r_trig_ha_off: R_TRIG;
+    r_trig_zigbee: R_TRIG;
+    
+    // Internal state
+    light_state: BOOL := FALSE;
+END_VAR
+
+(* === IMPLEMENTATION === *)
+// =====================================================
+// fb_light - Implementation (per redesign)
+// =====================================================
+// Priority (highest to lowest):
+// 1. HA OFF command  - Always turns light OFF
+// 2. HA ON command   - Always turns light ON
+// 3. Zigbee toggle   - Toggles current state
+// 4. Maintain current state
+// =====================================================
+
+// Edge detection for commands
+r_trig_ha_on(CLK := ha_on);
+r_trig_ha_off(CLK := ha_off);
+r_trig_zigbee(CLK := zigbee_sw);
+
+// State machine
+IF r_trig_ha_off.Q THEN
+    light_state := FALSE;
+ELSIF r_trig_ha_on.Q THEN
+    light_state := TRUE;
+ELSIF r_trig_zigbee.Q THEN
+    light_state := NOT light_state;
+END_IF;
+
+// Output assignment
+light_output := light_state;
+
+// Status feedback (read from actual relay)
+light_status := relay_status;