C# implementation of Siemens S7 connections with a focus on performance
The S7 protocol is a proprietary protocol for PLC communication with and between Siemens S7 PLC's. It's making use of COTP (Connection Oriented Transport Protocol, ISO 8073 / RFC 905) and TPKT (ISO Transport Service on top of the TCP Version 3, RFC 1006). The S7 protocol uses ConnectionRequest (CC) and ConnectionConfirm (CR) from COTP for connection management and COTP DataTransfer (DT) to wrap S7 protocol functions. A good description is available at The Siemens S7 Communication - Part 1 General Structure and The Siemens S7 Communication - Part 2 Job Requests and Ack Data.
Sally7 supports the most basic read and write actions to the DataBlock area.
All protocols are mapped to structs and enums with the intent to create a project that is easy to comprehend and extend.
Connect to a S7-1500 PLC at adress 192.168.0.15 on Rack 0, Slot 1
var connection = Sally7.Plc.ConnectionFactory.GetConnection(host: "192.168.0.15", cpuType: Sally7.Plc.CpuType.S7_1500, rack: 0, slot: 1);
await connection.OpenAsync();
Read 10 bytes from DataBlock 87 starting at address 54
var dataItem = new DataBlockDataItem<byte[]>
{
DbNumber = 87,
Length = 10,
StartByte = 54
};
await connection.ReadAsync(dataItem);
Console.WriteLine($"Read data: {BitConverter.ToString(dataItem.Value)}");