NOTE

As of version 4.2.172.0, the Beckhoff ADS library for .NET also includes support for Reactive Extensions, making this library obsolete. See here for more information: https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_adsnetref/7312584843.html&id=

TwinRx

TwinRx is a library for connecting a .NET application with a Beckhoff TwinCAT PLC program via Reactive Extensions (Rx) over ADS.

Features

• Create an IObservable for a PLC variable, bringing changes to the PLC variable into the Reactive world.
• Make use of Rx’s extensive event processing and querying capabilities to transform the observable into events of interest.
• Stream (write) an existing IObservable to a PLC variable
• Transparently reregister the notifications after a connection loss

Requires

• .NET 4.5 or higher
• Beckhoff TwinCAT PLC (v2 or v3)

Installation

• Install the NuGet package “TwinRx” using the NuGet Package Manager in Visual Studio

Example code

using System;
using System.Reactive.Linq;
using TwinCAT.Ads;
using TwinRx;
var adsClient = new TcAdsClient();
adsClient.Connect(801); // 801 for TwinCAT 2, 851 for TwinCAT 3
var client = new TwinCatRxClient(adsClient);
var counter = client.ObservableFor<short>("MAIN.var1", 20);
// Print out each value as it changes
counter.Subscribe(v => Console.WriteLine("Variable is now:" + v));
// Print out 10 values at a time
var buffered = counter.Buffer(10);
buffered.Subscribe(v => Console.WriteLine("Last 10 values were:" + String.Join(" - ", v)));
// Values including timestamp
var valuesWithTimestamp = counter.Select(i => new Tuple<short, DateTime>(i, DateTime.Now));
valuesWithTimestamp.Subscribe(Console.WriteLine);
// Take a single value each second
valuesWithTimestamp
    .Sample(TimeSpan.FromSeconds(5))
    .Subscribe(Console.WriteLine);
var myString = client.ObservableFor<string>("MAIN.var2");
myString.Subscribe(Console.WriteLine);
// Write a value to the PLC periodically
var valueEverySecond = Observable
    .Interval(TimeSpan.FromSeconds(1))
    .Select(i => (short) i);
var writer = client.StreamTo("MAIN.var3", valueEverySecond);
// Only even ones
var evens = client.ObservableFor<short>("MAIN.var4").Where(i => i%2 == 0);
var evensWithTimestamp = evens
    .Timestamp()
    .Zip(evens.TimeInterval(), (valWithTimestamp, interval) => new { val = "Even value is " + valWithTimestamp, interval });
evensWithTimestamp.Subscribe(Console.WriteLine);