Modbus Logic Engine

Path: src/ModbusLogicEngine.cpp

Revision History: Initial documentation

The Modbus Logic Engine is a programmable rule engine that allows defining conditional logic rules through Modbus registers. It evaluates conditions on register values and executes actions when conditions are met, providing automation capabilities without requiring firmware modifications.

REQUIREMENTS

ESP-32 microcontroller
Platform.io development environment
Modbus TCP/RTU implementation
Feature flag ENABLE_MB_SCRIPT must be defined in configuration

FEATURES

Rules-based automation through Modbus registers
Configurable conditions with multiple comparison operators
Multiple action types including:
- Writing to Modbus registers
- Setting coils
- Calling component methods
Debug flags for troubleshooting
Rule status monitoring and counters
Configurable evaluation interval

DEPENDENCIES

Component.h - Base component class
ArduinoLog.h - Logging functionality
ModbusTypes.h - Modbus type definitions
PHApp.h - Application context

BEHAVIOUR

The Modbus Logic Engine continuously evaluates rules at a configurable interval, checking conditions against Modbus register values and executing actions when conditions are met.

TODOS

PERFORMANCE

Consider adding a priority system for rules that need faster evaluation
Optimize condition evaluation by caching register values when multiple rules reference the same address
Implement batch processing for rules that write to sequential registers

SECURITY

Consider adding authentication for modifying rule configurations
Implement range checking for target addresses to prevent unauthorized access
Add validation for rule parameters to prevent malformed rules

COMPLIANCE

Ensure rule execution timing meets industrial control requirements
Document rule format for compliance with automation standards
Implement logging capabilities for audit trails in regulated environments

RECOMMENDATIONS

Use separate register blocks for different rule sets to improve organization
Implement a backup/restore mechanism for rule configurations
Consider a graphical rule editor for easier configuration
Add rule dependencies to allow chaining of rules

EXAMPLE

The Modbus Logic Engine is typically constructed early in the application startup:

#ifdef ENABLE_MB_SCRIPT
  modbusLogicEngine = new ModbusLogicEngine(
      this  // Owner (PHApp instance)
  );
  if (modbusLogicEngine) {
    components.push_back(modbusLogicEngine);
    Log.infoln(F("ModbusLogicEngine initialized."));

    // Register component methods that can be called from rules
    modbusLogicEngine->registerMethod(
        COMPONENT_ID_LED, // Component ID
        1,                // Method ID
        [this](short arg1, short arg2) -> short {
            // Example method implementation
            if (ledComponent) {
                return ledComponent->setPattern(arg1);
            }
            return E_COMPONENT_ERROR;
        }
    );
  } else {
    Log.errorln(F("ModbusLogicEngine initialization failed."));
  }
#endif

Modbus Logic Engine