CSComm3.SLC

A C# .NET library for communicating with Allen Bradley SLC and MicroLogix PLCs over Ethernet.

Status: Complete - Read and Write operations verified against real hardware

Overview

CSComm3.SLC is a C# port of the SLC driver functionality from pycomm3. It provides a simple API for reading and writing data to SLC 5/05 and MicroLogix PLCs using the PCCC protocol over EtherNet/IP.

Supported Hardware

• Allen Bradley SLC 5/05 (Ethernet-enabled)
• Allen Bradley MicroLogix 1100 (1763-xxx)
• Allen Bradley MicroLogix 1200 (1762-xxx)
• Allen Bradley MicroLogix 1400 (1766-xxx)
• Allen Bradley MicroLogix 1500 (1764-xxx)

Features

• EtherNet/IP session management
• CIP Forward Open/Close connections
• Read operations for all data types
• Write operations for integers and bits
• Device identity retrieval
• Async/await support
• Multiple tag reads in single call

Installation

# Clone the repository
git clone https://github.com/yourusername/cscomm3_slc.git

# Build the library
dotnet build

# Run tests
dotnet test

Quick Start

using CSComm3.SLC;

// Connect to PLC
using var plc = new SLCDriver("192.168.1.150");
plc.Open();

// Read a single integer
var tag = plc.Read("N7:0");
Console.WriteLine($"N7:0 = {tag.Value}");

// Read multiple tags
var tags = plc.Read("N7:0", "N7:1", "F8:0");
foreach (var t in tags)
{
    Console.WriteLine($"{t.Address} = {t.Value}");
}

// Write an integer
plc.Write("N7:1", (short)100);

// Write a bit
plc.Write("B3:0/0", true);

// Async read
var result = await plc.ReadAsync("N7:0");

Supported Data Types

Address Format	Type	Example	C# Type
Nx:y	Integer	N7:0	Int16
Fx:y	Float	F8:0	Single
Bx:y/z	Bit	B3:0/5	Boolean
Sx:y	Status	S2:37	Int16
Tx:y.ACC	Timer Accumulated	T4:0.ACC	Int16
Tx:y.PRE	Timer Preset	T4:0.PRE	Int16
Cx:y.ACC	Counter Accumulated	C5:0.ACC	Int16
Cx:y.PRE	Counter Preset	C5:0.PRE	Int16
I:y	Input	I:0	Int16
O:y	Output	O:0	Int16

API Reference

SLCDriver Class

public class SLCDriver : IDisposable
{
    // Constructor
    public SLCDriver(string ipAddress);

    // Properties
    public bool Connected { get; }
    public int Timeout { get; set; }  // milliseconds

    // Connection
    public bool Open();
    public void Close();

    // Read Operations
    public Tag Read(string address);
    public Tag[] Read(params string[] addresses);
    public Task<Tag> ReadAsync(string address);
    public Task<Tag[]> ReadAsync(params string[] addresses);

    // Write Operations
    public bool Write(string address, object value);
    public Task<bool> WriteAsync(string address, object value);

    // Device Info
    public DeviceIdentity GetIdentity();
}

Tag Class

public class Tag
{
    public string Address { get; }
    public object? Value { get; }
    public string? Error { get; }
}

Tech Stack

• Language: C# 12.0
• Runtime: .NET 8.0
• Testing: xUnit, FluentAssertions

Project Structure

cscomm3_slc/
├── src/
│   └── CSComm3.SLC/
│       ├── SLCDriver.cs          # Main driver class
│       ├── Tag.cs                # Tag result class
│       ├── CIP/                  # CIP protocol components
│       ├── PCCC/                 # PCCC protocol components
│       ├── Packets/              # EtherNet/IP packets
│       └── Exceptions/           # Custom exceptions
├── tests/
│   └── CSComm3.SLC.Tests/        # Unit tests (205 tests)
├── samples/
│   └── TestApp/                  # Sample application
└── docs/
    └── PRD.md                    # Product requirements

Testing

The library includes 205 unit tests covering:

• Tag address parsing
• PCCC protocol message building
• Data type encoding/decoding
• CIP packet construction

dotnet test

Verified Against Hardware

Successfully tested against:

• PLC: Allen Bradley 1747-L551/C (SLC 5/05)
• Firmware: C/13 - DC 3.54

Verified operations:

Operation	Status
Read Integer (N7:x)	Working
Read Status (S2:x)	Working
Read Float (F8:x)	Working
Read Bit (B3:x/y)	Working
Read Timer (T4:x.ACC)	Working
Read Counter (C5:x.ACC)	Working
Write Integer (N7:x)	Working
Write Bit (B3:x/y)	Working

License

See LICENSE file for details.

Acknowledgments

• pycomm3 - Original Python implementation
• Allen Bradley / Rockwell Automation - PLC hardware and protocols