Added 2 parameters for S7Endpoint to Disable PLC and load Tags dynamically

[lucagem]

Summary

Added dynamic endpoint configuration

✨ New Features

S7 Endpoint Configuration Interface

The image above shows the enhanced S7 endpoint configuration interface with numbered references to the new and modified features:

1. Address Field (Existing)

Standard IP address configuration for the PLC connection. This field was already functional and no modifications were made.

• Fixed value eg: 10.0.0.102
• Environment variable: ${S7_IP}
• Custom environment variable: ${YOUR_PORT_VAR}

2. Port Field (Enhanced)

Enhanced with environment variable support:

• Fixed value default: 102
• Environment variable: ${S7_PORT}
• Custom environment variable: ${YOUR_PORT_VAR}

3. Rack Field (Enhanced)

Enhanced with environment variable support:

• Fixed value default: 0
• Environment variable: ${S7_RACK}
• Custom environment variable: ${YOUR_RACK_VAR}

4. Slot Field (Enhanced)

Enhanced with environment variable support:

• Fixed value default: 2
• Environment variable: ${S7_SLOT}
• Custom environment variable: ${YOUR_SLOT_VAR}

5. PLC Enabled Field (NEW)

New field for dynamic PLC enable/disable:

• Empty or true: PLC enabled (default behavior)
• false or 0: PLC disabled
• ${S7_ENABLE}: Environment variable
• Custom environment variable: ${YOUR_ENABLE_VAR}

When PLC is disabled:

• The endpoint remains in "offline" state
• Write operations fail with "PLC disabled" error
• No connection attempts are made

6. CSV File Path Field (NEW)

New field for external variable configuration:

• Absolute path: C:\config\s7_tags.csv
• Relative path: ./config/tags.csv
• Environment variable: ${S7_CSV_FILE}
• Custom environment variable: ${YOUR_CSV_VAR}

Dynamic Configuration Management

CSV File Loading

The CSV file allows loading the variable list from an external file instead of the node configuration. This facilitates:

• Reusing the same configuration across different installations
• Centralized tag management
• Synchronization with external configuration systems

CSV file format:

address<TAB|;>name
DB1,REAL0	Temperature_1
DB1,REAL4	Temperature_2
MB100	Memory_Byte_100

The CSV file takes priority over internal configuration. If the file doesn't exist or is empty, the node configuration is used.

Environment Variables Benefits

Using environment variables for fields 1-6 allows configuring different environments (development, test, production) using the same flow but with different connection parameters.

Technical Notes

• Environment variables are automatically resolved by Node-RED
• CSV loading occurs only at node startup
• In case of CSV errors, the node configuration is used with a warning message
• CSV parsing supports TAB ( ) and semicolon (;) separators
• Empty lines in CSV are ignored
• Fields 2, 3, 4 maintain backward compatibility with numeric values
• Fields 5 and 6 are completely new additions

[lucagem]

🔄 Updated to latest master (v3.1.0)

Hi maintainers! 👋

This PR has been automatically updated to be fully compatible with the latest master branch.

Why this feature is valuable:

• Multi-environment support - Same flows work across dev/staging/production
• CSV configuration - Centralized tag management for enterprise deployments
• Zero breaking changes - Fully backward compatible
• Production-ready - Addresses real industrial automation challenges

The dynamic configuration capabilities (environment variables + CSV loading) are highly requested features in industrial Node-RED deployments.

Ready for review - Happy to address any feedback! 🙏

Thanks for maintaining this excellent S7 library!