WPF and OPC: a full sample project with RSLinx and databinding

Now that i wrote about databinding, pages and so on, i publish an example on how to connect real time values readed from a PLC (in this case an Allen Bradley PLC, but it can be anyone), update an object collection with this values, and then display them on different pages.

As usual i have my 2 tanks and i want to read what liquid is inside every tank (defined as 16bit integer).
1st tank word is N7:0, second is N7:1
For each tank there is a button that changes its content(writing the PLC word).

This is the new code to analyze: i have 2 buttons that writes the words on PLC, then i have the callback where i read values in PLC, cast them and update my objects.
This objects are defined in the OPC Client class and they are defined as "public"  because i want to access their properties from every window that needs to display real time values or to control them.


This is the MainWindow, where the program begin and where i create the opcclient object as static.
To access to it's properties i just need to bind UI items by databinding.

To access the properties of objects in another window or page, i do like in this example.

And this is the final result

This is how the setup for PLC OPC Server, that should be called as [UNTITLED_2]

Hope it's helpful.
Full solution here:

http://www.mesta-automation.com/Downloads/opc%20sample%202.rar

Previus post describe more in details what's used in this example, if you're interested.

OPC Client c# .Net Sample (RSLinx OPC server)

Hi, a big problem about connecting PLC to PC is the "from where should i start?".
And that's why i suppose people choose commercial SCADA instead of .Net (they already has drivers and so on).
Well, if it was for winforms, i would agree that winforms sucks, they got a lot of bugs and so on, so i would choose a commercial SCADA too.
But since WPF and Silverlight was released, .Net is really more more powerful and beautiful, the code became easier with the binding system and industrial PCs + OPC servers cost always less (and sometimes it's possible to find free drivers).

This post is an example of communication with RSLinx OPC Server (but i use OPC Foundation libraries so the process is the same for every OPC server).


So let's strart by adding a reference to the OPC Foundation dlls:
- OpcNetApi.Com.dll
- OpcNetApi.dll
- OpcNetApi.Xml.dll

Then create Items that are shared for the all the form (or the project)

Then create a button to connect (or just place the code after InitializeComponent(); if you want to autoconnect when the program starts)
Set the URL (in this sample there is the one of RSLinx) then add a group, add some items with theyr connection string, set the update time and the callback for the items that you want to read, then set a group for writings.

 This is the sample callback where i assign values that i read to a custom object.
Remember that the GUI and the OPC client runs on two different threads, so it's needed to use anonymous method for this (just use like is written in the sample).
With WPF and INotifyPropertyChanged it's not needed this.
You can just bind all your objects to the GUI items property, and this is really amazing and simple.

 This is the way that i found to write a single word, basically i create a new one, i check if in the write group there is already one of them, else i add it.

 Writing was always a problem for me, but when i found this way, i got all i needed

This is a sample of how i write from a button reading a textbox

IMPORTANT UPDATE: This code is written on a Micrologix / SLC platform and it reads only integer values, so when i read a value it's supposed to be a 16-bit word: that's why i cast it to (short). Remember that if you read a REAL value (F8:0 for example) you sould cast it to float and if you read from Controllogix or CompactLogix, you have to convert it to (int) because they are 32-bit words.

This is the complete solution:

http://www.mesta-automation.com/Downloads/OPC%20Client.rar

This is another link for a Twincat OPC Server, that is similar to the RSLinx.
http://infosys.beckhoff.com/content/1033/tcopcserver/html/sample1_netapi.htm?id=18186

UPDATE: i wrote a recent post here where i wrote a full sample with WPF and an OPC client in c#. watch it here: http://mestaa.blogspot.com/2010/12/wpf-and-opc-full-sample-project-with.html

[UPDATE #2]: i made a video that explains how to use the code provided: check it here: http://www.mesta-automation.com/opc-client-with-c-an-how-to-video/