---
title: "CommandMessage Class - Message Parsing System"
description: "Documentation for the CommandMessage class used to parse and structure messages in a Modbus system"
keywords: ["ESP-32", "Modbus", "communication", "command parsing", "messaging"]
---

## CommandMessage

**Path**: [src/modbus/command_message.h](../src/modbus/command_message.h)

**Revision History**: Initial documentation

The CommandMessage class provides a structured approach to parse, validate, and manage command messages within the system. It supports message serialization and deserialization with defined start/end markers and delimiters. This class is designed for efficient messaging in industrial Modbus-485 communications.

## REQUIREMENTS

- No specific hardware pins required
- Requires StringUtils and enums support

## PROVIDES

- **CommandMessage**: The main class for message handling
- **DEBUG_MESSAGES_PARSE**: Conditional compilation flag for verbose message parsing output
- **DEBUG_MESSAGES_PARSER**: Macro for debug logging of message parsing operations
- **MESSAGE_TOKENS**: Constant defining the expected number of tokens in a valid message

## FEATURES

- Structured message storage with ID, verb, flags, and payload
- Timestamp tracking for message receipt
- Validation of message format with start/end markers
- Parsing of delimited message content
- Clear method for resetting message state
- Match checking for message format validation

## DEPENDENCIES

- [Vector](../src/Vector.h)
- [ArduinoLog](../src/ArduinoLog.h)
- [StringUtils](../src/StringUtils.h)
- [Enums](../src/modbus/enums.h)

```mermaid
graph TD
    CommandMessage --> StringUtils
    CommandMessage --> ArduinoLog
    CommandMessage --> Vector
    CommandMessage --> Enums
```

## BEHAVIOUR

```mermaid
sequenceDiagram
    participant Client
    participant CommandMessage
    
    Client->>CommandMessage: Create message with id, verb, flags
    Client->>CommandMessage: parse(message)
    CommandMessage->>CommandMessage: clear()
    CommandMessage->>CommandMessage: Extract content between markers
    CommandMessage->>CommandMessage: Split by delimiters
    CommandMessage->>CommandMessage: Validate token count
    CommandMessage->>CommandMessage: Assign id, verb, flags, payload
    CommandMessage->>CommandMessage: Set timestamp
    CommandMessage-->>Client: Return success/failure
```

## TODOS

### PERFORMANCE

- Consider pre-allocating memory for the message parsing to avoid heap fragmentation
- Evaluate the use of String vs. char arrays for payload handling in memory-constrained environments
- Potential for optimizing token parsing with a more efficient approach than strtok

### SECURITY

- Consider implementing message integrity checking (checksums or CRC)
- Add length validation to prevent buffer overflows
- Implement validation of message payload content based on expected verb/command

### COMPLIANCE

- Ensure all message processing complies with Modbus protocol standards where applicable
- Consider adding support for standard industrial message formats

### RECOMMENDATIONS

- Add support for binary payloads for more efficient communication
- Consider implementing a message queue system to handle multiple messages
- Add methods to serialize a CommandMessage back to a string for bidirectional communication
- Consider adding timeout functionality for message handling