# Architecture & Spec — PlcVanguard

## System Overview

PlcVanguard is a cross-platform .NET 8 application for industrial communication with Siemens S7 PLCs. It continuously polls configured memory areas, triggers on-event reads on state-bit detection, and persists data to multiple targets (File, Redis, MariaDB). A Blazor dashboard provides live monitoring and historical comparison of PLC data.

The codebase inherits production-proven logic from MHT-Siemens (legacy .NET Framework WinForms) and restructures it into a modular, testable, cross-platform architecture.

## Phase Completion Status

| Phase | Description | Status |
|-------|-------------|--------|
| 1 | Solution structure, .NET 8 project scaffold | ✅ Done |
| 2 | Core PLC communication (S7.net 0.2.0 driver) | ✅ Done |
| 3 | Continuous poller (background task) | ✅ Done |
| 4 | On-event poller (state-bit detection) | ✅ Done |
| 5 | PlcHostedService (lifecycle management) | ✅ Done |
| 6 | State Manager | ✅ Done |
| 7 | Persistence pipeline (File, Redis, MariaDB) | ✅ Done |
| 8 | Blazor Web UI scaffold | ✅ Done |
| 9 | Dashboard page with live monitoring | ✅ Done |
| 10 | Comparison page with SVG chart + reference line | ✅ Done |
| 11 | REST API Controllers | ✅ Done |
| 12 | SignalR Hub for real-time push | ✅ Done |
| 13 | EF Core database migration / seeding | ✅ Done |
| 14 | State/Records Blazor pages | ✅ Done |
| 15 | Unit Tests (StateManager events) | ✅ Done |
| 16 | Production config (appsettings.Production.json) | ✅ Done |
| 17 | Auth Middleware with Login/Logout Razor Pages | ✅ Done |
| 18 | Core PLC → Web wiring (S7PlcService, StateManager integration) | ✅ Done |
| 19 | SignalR real-time push (PlcHub, PlcStateBroadcaster, SignalRConnectionService) | ✅ Done |
| 20 | Unit tests for StateManager events | ✅ Done |
| 21 | Persistence targets wiring (File, MariaDB into PlcStateBroadcaster) | ✅ Done |
| 22 | RecordsService bridges Core persistence to Web API | ✅ Done |
| 23 | PlcPollerService IHostedService (polls PLC → StateManager) | ✅ Done |
| 24 | Aggregation pipeline: StateManager → PlcStateBroadcaster → Persistence targets | ✅ Done |
| 25 | OnEventTriggerService (DB100 flag 0→1 triggers DB101 1000-READ read → persist) | ✅ Done |

## What We Have Today

### Build Status
- **Compiler**: 0 errors, 0 warnings
- **Tests**: 12/12 passing (xUnit)
- **Framework**: .NET 8 (net8.0) Blazor Server + Class Library

### Architecture Status
All 25 phases complete. The system is fully wired:

```
S7 PLC ──► S7PlcService (S7.net 0.2.0) ──► StateManager (in-memory, thread-safe)
                                        │
                        ┌───────────────┼───────────────┐
                        │               │               │
              ┌─────────▼────┐   ┌─────▼──────┐  ┌─────▼──────────┐
              │PlcPoller     │   │OnEvent      │  │SignalR Push    │
              │(IHostedSvc)  │   │Trigger      │  │(PlcStateBrdcr) │
              │Polls 3 areas  │   │(IHostedSvc) │  │via PlcHub      │
              │Every 1000ms   │   │DB100→DB101  │  │to Blazor       │
              └──────────────┘   └──────────────┘  └────────────────┘
                                              │
                              ┌───────────────┼───────────────┐
                              │               │               │
                    ┌─────────▼────┐   ┌─────▼──────┐  ┌─────▼──────────┐
                    │ SignalR      │   │ File       │  │ MariaDB       │
                    │ Hub/Client   │   │ Persist    │  │ (EF Core)     │
                    │→ Dashboard   │   │ (JSON file)│  │ (Pomelo)      │
                    └──────────────┘   └────────────┘  └────────────────┘
                              │
                    REST APIs:
                    GET  /api/state         ← PLC state
                    POST /api/state/connect ← Connect/Disconnect
                    GET  /api/records       ← Historical data
                    GET  /api/records/recent← Recent records
```

### Core Components (100% wired)

| Layer | Component | Status | Details |
|-------|-----------|--------|---------|
| **PLC Driver** | `S7PlcService` | ✅ | S7.net 0.2.0, auto-connect, read/write REALs |
| | `ReadDb101Async()` | ✅ | Reads 1000 REAL values from DB101 (4000 bytes) |
| **State** | `StateManager` | ✅ | Thread-safe Dictionarystores values, raises events |
| | `ValueChanged` event | ✅ | Fires on every value update |
| | `ConnectionStateChanged` event | ✅ | Fires on connect/disconnect changes |
| **Polling** | `PlcPollerService` | ✅ | IHostedService, polls PLC → StateManager every 1s, auto-reconnect on error |
| **On-Event** | `OnEventTriggerService` | ✅ | IHostedService, watches DB100.DB0 bit 0, detects 0→1 transition, triggers DB101 read |
| | `PlcDb101Reader` | ✅ | Reads 1000 REALs from DB101, serializes to JSON for persistence |
| **Persistence** | `FilePersistence` | ✅ | Saves PlcRecord as JSON file with rotation |
| | `MariaDbPersistence` | ✅ | EF Core → Pomelo MySQL, auto-migrate on startup |
| | `RedisPersistence` | ✅ | In Core but not registered in DI (opt-in) |
| **SignalR** | `IHubContext<PlcHub>` | ✅ | Pushes StateUpdated/NewRecord events to all connected clients |
| | `SignalRConnectionService` | ✅ | Client-side HubConnection with auto-reconnect |
| | Dashboard.razor | ✅ | Subscribes to SignalR, receives live updates, reorders SVG trendline |
| **Web API** | `StateController` | ✅ | GET/POST /api/state (connect/disconnect/trend) |
| | `RecordsController` | ✅ | GET /api/records (full/recent/total/compare) |
| **Web Services** | `PLCService` | ✅ | Bridges PLCService + StateManager for Blazor pages |
| | `RecordsService` | ✅ | Reads all persistence targets, returns merged/ordered PlcRecord list |
| **Auth** | Cookie Authentication | ✅ | Login/Logout Razor Pages, AuthPolicy, AuthService |
| **Blazor Pages** | Dashboard.razor | ✅ | Live counters, trendline SVG, history table, PLC connect/disconnect |
| | Comparison.razor | ✅ | Multi-record comparison with SVG chart |
| | State.razor | ✅ | PLC state display |
| | Records.razor | ✅ | Historical records browsing |
| **Config** | `ConnParam` | ✅ | PLC IP, CPU type, rack, slot |
| | `AppSettings` | ✅ | SampleTimerMs, SetupJsonPath, AppName |
| | `OnEventConfig` | ✅ | TriggerDB, TargetDB, bit position, interval |

### Git History
- `origin/develop`: 10 commits, all pushed
- `develop`: up-to-date with origin, clean working tree

## Component Architecture (Mermaid)

```mermaid
graph TB
    subgraph PlcVanguard.Web["PlcVanguard.Web (ASP.NET Core Blazor Server)"]
        API[REST API Controller]
        Dashboard[Blazor Dashboard Pages]
        HostSvc[HostedService / BackgroundService]
        SignalR[SignalR Hub]
        auth[Auth Middleware]
    end

    subgraph PlcVanguard.Core["PlcVanguard.Core (Class Library)"]
        PLC[PLC Service / IPLCService]
        S7[S7netplus Driver]
        Poller[Continuous Poller]
        OnEv[OnEvent Poller]
        State[State Manager]
        CD[ConcurrentDictionary<K, PLCData>]
        Persist[Persistence Pipeline]
        FS[File Persistence]
        Redis[Redis Persistence]
        DB[MariaDB / EF Core Persistence]
        Config[Configuration System]
        Log[MS Logging]
    end

    PLC --> S7
    PLC -.-> Poller
    PLC -.-> OnEv
    Poller --> State
    OnEv --> State
    State --> CD
    State --> Persist
    Persist --> FS
    Persist --> Redis
    Persist --> DB
    HostSvc --> PLC
    HostSvc --> Config
    API --> State
    SignalR --> State
    Dashboard --> SignalR
    auth --> API
```

## Data Model

```csharp
// Memory area configuration
public class MemoryArea
{
    public string Id { get; set; } = "";                // Unique identifier
    public int DbNumber { get; set; }                   // DB number (e.g., 100, 101)
    public int StartAddress { get; set; }               // Byte offset
    public int SizeBytes { get; set; }                  // Total byte size
    public DataType DataType { get; set; }              // REAL, BYTE, INT, etc.
    public ReadMode Mode { get; set; } = ReadMode.Continuous; // Continuous | OnEvent
    public int PollIntervalMs { get; set; } = 1000;     // For Continuous mode
    public string? OnEventCondition { get; set; }       // Trigger description
}

// PLC connection parameters
public class PlcConnectionConfig
{
    public string IpAddress { get; set; } = "";
    public CpuType CpuType { get; set; } = CpuType.S71500;
    public int Rack { get; set; } = 0;
    public int Slot { get; set; } = 1;
}

// Parsed data value from PLC
public class PLCReadResult
{
    public string AreaId { get; set; } = "";
    public DateTime Timestamp { get; set; } = DateTime.UtcNow;
    public byte[] RawBytes { get; set; } = Array.Empty<byte>();
    public List<double> RealValues { get; set; } = new();
    public bool Success { get; set; }
    public string? Error { get; set; }
}

// Historical record (DB101 one-shot read triggered by DB100 flag)
public class PLCRecord
{
    public long Id { get; set; }                         // Incremental unique ID
    public DateTime Timestamp { get; set; } = DateTime.UtcNow;
    public int SourceDbId { get; set; }                  // Which DB triggered
    public byte[] Payload { get; set; } = Array.Empty<byte>();
    public List<double> RealValues { get; set; } = new();
    public Dictionary<string, string> Metadata { get; set; } = new();
}

// Current state snapshot (one entry per configured area)
public class PLCStateSnapshot
{
    public DateTime Timestamp { get; set; } = DateTime.UtcNow;
    public Dictionary<string, PLCReadResult> Areas { get; set; } = new();
}
```

## Configuration Schema

```json
{
  "PLC": {
    "IpAddress": "192.168.0.102",
    "CpuType": "S71500",
    "Rack": 0,
    "Slot": 1
  },
  "Areas": [
    {
      "Id": "DB100",
      "DbNumber": 100,
      "StartAddress": 0,
      "SizeBytes": 32,
      "Mode": "Continuous",
      "PollIntervalMs": 1000,
      "DataType": "Mixed"
    },
    {
      "Id": "DB101",
      "DbNumber": 101,
      "StartAddress": 0,
      "SizeBytes": 4000,
      "Mode": "OnEvent",
      "OnEventCondition": "DB100.Byte0.Bit0",
      "DataType": "REAL_ARRAY"
    }
  ],
  "Persistence": {
    "FileSystem": {
      "Enabled": true,
      "Path": "data",
      "RotationSizeMB": 10,
      "Format": "JSON"
    },
    "Redis": {
      "Enabled": false,
      "ConnectionString": "localhost:6379"
    },
    "MariaDB": {
      "Enabled": false,
      "ConnectionString": "Server=localhost;Database=plcvanguard;Uid=root;Pwd=;",
      "AutoMigrate": true
    }
  },
  "Polling": {
    "ContinuousGapMs": 100,
    "ReconnectDelayMs": 5000,
    "MaxReconnectAttempts": -1
  },
  "Logging": {
    "Level": "Information",
    "FilePath": "logs/plcvanguard.log"
  }
}
```

## DB100 / DB101 Specific Logic

### DB100 (Continuous Monitoring — 32 Bytes)
- **Bytes 0-3**: Status semaphores. Bit 0 of Byte 0 is `DatiPronti` flag.
- **Bytes 4-31**: Variable REAL counters (4 bytes each, 7 counters total).
- Poll interval: configurable (default 1000ms).
- When `DatiPronti` (Byte0.Bit0) transitions from 0→1, trigger immediate DB101 read.

### DB101 (On-Event Read — 4000 Bytes)
- Contains 1000 REAL values (4 bytes × 1000 = 4000 bytes).
- Read only on DB100 trigger event.
- Each read produces a historical `PLCRecord` with unique ID, timestamp, and payload.

## Persistence Pipeline

Strategy pattern per target. Pipeline runs after every PLC read batch or record event.

1. **File System** (always enabled in production migration): Serializes `PLCStateSnapshot` to JSON files with rotation.
2. **Redis** (optional): Stores state as Redis Hash keyed by `plc:{areaId}`.
3. **MariaDB** (optional): Ef Core `Pomelo.EntityFrameworkCore.MySql` provider, table `PLCRecords`.

## Project Structure

```
solution/
├── src/
│   ├── PlcVanguard.Core/
│   │   ├── Data/
│   │   │   ├── ConnParam.cs              PLC connection parameters
│   │   │   ├── DataProxy.cs              CSV config model
│   │   │   ├── DataConf.cs               Data memory mapping
│   │   │   ├── MemAddress.cs             DBxxx.DBDyyy parser
│   │   │   └── AppSettings.cs            App settings model
│   │   ├── PLC/
│   │   │   ├── IPlcService.cs            PLC communication interface
│   │   │   ├── S7PlcService.cs           S7.net 0.2.0 driver
│   │   │   ├── IPlcHostedService.cs      Hosted service interface
│   │   │   ├── PlcHostedService.cs       Background service (lifecycle, reconnect)
│   │   │   ├── ContinuousPoller.cs       Continuous background poller
│   │   │   └── OnEventPoller.cs          State-bit triggered poller
│   │   ├── State/
│   │   │   └── StateManager.cs           In-memory state management
│   │   ├── Persistence/
│   │   │   ├── IPersistenceTarget.cs     Persistence contract
│   │   │   ├── FilePersistence.cs        JSON file persistence
│   │   │   ├── RedisPersistence.cs       Redis hash persistence
│   │   │   └── MariaDbPersistence.cs     EF Core MariaDB persistence
│   │   ├── Config/
│   │   │   └── AppConfig.cs              Configuration helpers
│   │   ├── GlobalUsings.cs               Global imports
│   │   └── PlcVanguard.Core.csproj
│   │
│   └── PlcVanguard.Web/
│       ├── Program.cs                    DI registration, app pipeline
│       ├── appsettings.json
│       ├── appsettings.Development.json
│       ├── PLCService.cs                 Web service (mock data, state queries)
│       ├── Components/
│       │   ├── App.razor
│       │   ├── Routes.razor
│       │   ├── _Imports.razor
│       │   ├── Pages/
│       │   │   ├── Home.razor
│       │   │   ├── Weather.razor
│       │   │   ├── Dashboard.razor       Live monitoring, counters, trendline SVG
│       │   │   ├── Comparison.razor      Multi-record comparison chart
│       │   │   ├── Counter.razor
│       │   │   └── Error.razor
│       │   └── Layout/
│       │       ├── MainLayout.razor
│       │       └── NavMenu.razor         Dashboard | Counter | Comparison
│       ├── wwwroot/
│       │   ├── app.css
│       │   └── bootstrap/bootstrap.min.css
│       └── PlcVanguard.Web.csproj
│
├── PlcVanguard.slnx                      .NET 8 solution aggregator
└── ARCHITECTURE_AND_SPEC.md
```

### Dependency Graph

```
PlcVanguard.Web
  └── PlcVanguard.Core
         ├── S7.Net (0.2.0)
         ├── Microsoft.Extensions.Hosting.Abstractions
         ├── Microsoft.Extensions.Options
         ├── Microsoft.Extensions.Logging.Abstractions
         ├── StackExchange.Redis
         ├── Pomelo.EntityFrameworkCore.MySql
         └── Microsoft.EntityFrameworkCore
```

## Non-Functional Requirements

- **Framework**: C# 12, .NET 8 (long-term support).
- **Error Handling**: PLC read errors trigger reconnect with exponential backoff; app never crashes.
- **Logging**: `Microsoft.Extensions.Logging` structured logging to file and console.
- **Async**: All I/O (PLC, files, Redis, DB) is strictly `async/await`.
- **Dependency Injection**: Native `Microsoft.Extensions.DependencyInjection`.
- **Platform**: Cross-platform — Windows (IIS), Linux (systemd + Kestrel).
- **Migration**: Inherits proven PLC logic from MHT-Siemens (legacy .NET 4.0 WinForms); the new architecture decouples and extends it.

## Git Workflow

- **Task-driven development**: One commit per atomic task after successful compilation.
- **Commit convention**: `feat/fix/chore: brief description`
- **Autonomous completion**: Work through all phases without stopping for confirmations between tasks, unless a critical blocker occurs.