I am using OPC Foundation's OpcNetApi.dll to communicate with an OPC DA server.
I am curious if there is a programatic way to kill specific connections which are currently active on the server using this library or a similar library.
I'm not positive, but I don't think what you are asking for is always possible (without a debugger). OPC is based on Microsoft COM. There are two ways that COM can be implemented:in-proc and out-of-proc. The choice depends on the OPC server vendor.
With an in-proc implementation, if you are running the OPC client on the same machine as the OPC server then the OPC server is just a dll that is loaded directly into the memory space of the OPC client. This dll exposes the OPC interfaces like CreateGroup, ReadAllItems, etc. Now it is probably getting the actual data through some other mechanism (named pipe, TCP/IP, etc) but this depends again on the OPC server implementation. The only way to really force stop this OPC server is to end the OPC client or get the OPC client program. Of course the OPC client or OPC server may already have implemented a mechanism to end, but there is not guarantee.
If it is an out-of-proc OPC implementation then the OPC server will run in a separate executable so you can find the name of that executable and terminate it. (You can search in regedit for the name of the OPC server to find the corresponding executable name). If I remember correctly, the OPC server can be designed so all clients share one executable or each OPC client gets their own instance of the executable.
If you are running the OPC server remotely then it is probably going to be loaded inside of a stub program if its an in-proc implementation and then tied to RPC. If you block the ports that RPC communicates over I think most clients would decide to disconnect after a while, although there is no guarentee they won't try to reconnect later.
Here's some more information:
https://www.opcsupport.com/link/portal/4164/4590/Article/711/May-I-get-a-In-Proc-and-Out-Of-Proc-explanation
Related
Has anyone seen anything on Windows Server 2019 that would prevent browsing the network in a Active Directory domain environment to find available OPC servers on remote hosts when all other OPC communications seem to be functioning normally and file share browsing seems to also be functioning?
There is something I'm missing here, but I cannot find it. Since the core OPC functions are working, tools like OPC Expert are not showing any errors and guides for DCOM settings from OSIsoft, KEPware, and OSI Institute are all being used to no avail. None of the DCOM settings seem to be addressing the CLSID network browsing. If a client has the ability to supply a remote host and query that host, the OPC services enumeration works just fine. The problem is that we are attempting to use clients that do not have any features to manually define the servers and solely relies on the network browsing functions.
Please tell me someone else has seen this behavior. I suspect that it is some network security feature of Windows Server 2019, but I can't find any documentation that points to what might be causing this function to fail. Worse, the function is completing normally, but with zero results, so I don't even have error messages to track the issue down with.
It really depends on the application you are using. There are many ways for an OPC Client to find the remote OPC Server. Most clients will use a combination of the folowing:
OPCEnum. In particular the heavy lifting is done using EnumClassesOfCategories which is part of Component categories Manager. Does not crawl through registry.
GetOPCServers(). This is a method is available as part of an interface called IOPCAutoServer which comes from the OPC foundation itself (via OPCDAAuto.dll)
CLSIDFromProgID() first to get the CLSID and then does the CoCreateInstanceEx().
When CLSIDFromProgID() fails, it falls back to using OPCEnum to list all OPC servers before making a connection.
That means that you would first need to find out what your client application is using to list the OPC Servers.
Then, on the Windows Security side of things, depending on the OS version of both nodes, you may need to disable Simple File Sharing mode (that is the case for Windows XP and older)
If it uses OPCEnum, you will need to configure DCOM for OPCEnum as well, which is the recommended method to list remote OPC Servers.
If the application only supports remote registry lookup to find the OPC Server, then you will need to grant access to the account connecting from the client to the Server
I have Analyzer which connects to a computer with cat5 cables . This Computer reads the data through a software called ComVisioner .ComVisioner has two Modes, one is Server Mode and Other is Client Mode A Server software acts as the engine in the system, providing one or more clients with information.
Server version is installed on a single computer . Once Server version is installed it collects data, performs calculations, produce reports and so on.
The ComVisioner client runs in the same computer as the server. Other clients can access the same single server through a network, providing that the software license allows more than one client at the same time
so there is Two client computers who access the as mentioned above .this all connection is done by Network cables . This part is fine
As License of Client is very expensive our company wants to add a OPC software so that more user can acquire data .As i have no knowledge on Opc part please suggest me How can i do it ?. what sort of software should i use ?. Can i install this software different pc with is connected in same network
There is also one more software installed in that computer which pushes the data as Modbus protocol
First, you need to make sure that the ComVisioner can give OPC data. (work like opc server). This should be indicated in the documentation.
Download the free OPC client, and make sure you can read the data (for example you can use, matrikon opc explorer or kepware quick client (I like it more, it goes together with KepServerEx, to download them you need to register)
If you can connect and see the data, then there will be no problems with access to the data. Next you need to find a solution for which Opc client suits you. Probably some SCADA system, but some good SCADA also cost a lot, and require a lot of development time.
I don't recommend you try to use modbus if there is opc. If you will use modbus you will have many problem with addressing and value format.
ps
We had a problem with expensive licenses. As a result, we solved the problem by give access for programm for clients via RDP (remote desktop connection)
Is it possible to connect an OPC UA server to another OPC UA server, in order to redistribute its data?
In fact, I have a small device which runs a small OPC UA server that exposes some data. The device is running in a private network. Then I have the main OPC UA server accessible from the internet, where I would like to view some of the small device's data, together with some more generic data.
Yes, it's possible, you just need a server that has this feature. It's not a standard part of OPC UA that any server will be able to do.
One option would be to use KEPServerEx's client driver.
OPC UA is a server-client architecture. Therefore, you cannot make two servers talk to each other directly. There must always be an OPC UA client implementation between them. Yes, KepServerEX does support this feature as having an OPC UA Client Driver out-of-the-box. However, you can implement your own little OPC UA client between the servers as a gateway too, which may suit your solution better I believe.
As far as I understand this will be possible by using an OPC UA Aggregation Server as main server (which is accessible from the internet).
You could test it with the open source UA-NetStandard Aggregation Server.
I'm trying to access an OPC Server on a Windows Machine using a Modbus Master on Linux and was wondering if that's possible
Not typically. You should use an OPC client.
No. OPC and Modbus are completely different.
Tipically you see an OPC server accessing a Modbus slave. You can model an OPC server as a two-layered component. The "upper" layer talks OPC with OPC clients. The "bottom" layer talks whatever protocol you want (in this example Modbus). The server's main task is to move data through these layers.
We can't get our PLC to reliably connect with KEPServerEX (OPC).
I was wondering if anyone else here at SOF has experience working with PLC and OPC. If so do they have any tips on making a reliable connection with our OPC Server. We currently use KEPServerEX for our OPC, but if anyone knows a better program to use we are open to suggestions.
I use Kepware OPC server for MODBUS TCP, Simatic S7 and Yokogawa for more then 5 years on 4 servers in industrial environment without any problems. It was easy to set up and showed no problems during exploatation. Actually, it was so nice that we decided to not use it only when it doesn't support the device we have (which is rare, and mostly happens when I have to develop custom OPC server). Kepware OPC server is even able to use reserved PG connection for connection to Siemens PLCs (unlike Simatic OPC Server, this is good if you have limited number of connections like in CP343 LEAN version communication module). It will also save you $$$$$ if you use data from it in some historian like OsiSoft PI which charges per OPC server connections, since all Kepware OPC servers will show as single OPC server to Osisoft PI. The only thing that made me angry was that after some trial time it stopped without warning all servers (including licenced ones) when I was evaluating one new OPC server I was supposed to try out. Have you tried Kepware technical support? Have you checked your cabling? Are you aware that trial version will stop after some time?
As an alternative you can try Matrikon OPC servers. They are also very good and run without problems.