SunSpec.NET

This repository implements the SunSpec modbus specification in .NET. It is inspired by pysunspec2.

Getting Started

There is a rudimentary unit test in SunSpec.Integration.Test which gives a brief idea of how the library is intended to be used.

Server

The server currently assumes Modbus TCP. There is no particular reason for this to remain the case, as the underlying Modbus library it uses supports both TCP and serial.

Create a server and initialise it:

SunSpecServer server = new SunSpecServer();
server.Initialise();

This will add the 'Common' model that is, er, common to all SunSpec devices.

Add further models by calling RegisterModelBuilder:

LithiumIonBankBuilder bankBuilder = new LithiumIonBankBuilder();
server.RegisterModelBuilder(bankBuilder);

Some models contain repeating groups: they can be added by methods on the model builders themselves:

bankBuilder.AddLithiumIonBankString();

When you have composed your model builders, call Build and then Start:

server.Build();

server.Start();

Once built, each builder's Model property will be populated with the constructed model. Set values on this for them to be retrieved by clients.

Writable values have an event associated with them. Subscribe to the event to be notified when a client modifies that value:

DERCtlACBuilder derAcControlsBuilder;
...
derAcControlsBuilder.Model.ActivePowerSetpointWChanged += OnActivePowerSetpointWChanged;

private void OnActivePowerSetpointWChanged(object? sender, EventArgs e)
{
    // do something in response to changed value here
}

Client

The client is less mature than the server; so far, its main purpose is to provide a counterpart to the server in unit tests.

Create a ModbusClient (TCP or serial) and connect it as appropriate.

ModbusTcpClient tcpClient = new ModbusTcpClient();
tcpClient.Connect(new IPEndPoint(IPAddress.Loopback, 502), ModbusEndianness.BigEndian);

Create a SunSpecClient and pass the constructed ModbusClient to it, then call ScanAsync.

SunSpecClient client = new SunSpecClient(tcpClient);
await client.ScanAsync();

This will discover the models available on the server and proxies constructed for them so that their values can be read. Those proxies can be accessed from the Models property:

LithiumIonBank? lithiumIonBank = client.Models.OfType<LithiumIonBank>().FirstOrDefault();
Console.WriteLine($"Voltage is {lithiumIonBank.AverageStringVoltage}");

Model Generation

The model generator is quite comprehensive now. It supports:

• repeating groups, including where their counts are specified in a given register
• automatic handling of scale factors (accessible from the ScaleFactors property on a given model)

At present, mainly for aesthetic reasons, property names are derived from the SunSpec label field rather than the name field. A reasonable enhancement would be to make this configurable.

Dependencies

FluentModbus (fork)