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Empty OPC items tree when browsing the Merz OPC SAIA server

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07 Dec 2022 13:33 #11313 by micham
Thank you.

You may see this case as closed.

Mike
The following user(s) said Thank You: support

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07 Dec 2022 11:04 #11312 by support
Well, I think you understand that the since also the Matrikon OPC Explorer (and presumably other clients) have the problem, there likely isn't anything to be fixed in QuickOPC.

It can be a problem in the OPC Server. It can still be something that can be resolved by system configuration, although you are right that is probably is not a DCOM issue. But it is not a DCOM not because the OPC Server runs locally (there are still settings in DCOMCNFG that affect how it works locally), but because the symptoms are that there is no error but simply an empty tree. DCOM problems would show as some kind of an error.

Regards

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06 Dec 2022 18:53 #11310 by micham
Hi,

Thank you for your answer.

Yes. I tried Matrikon OPC Explorer. If I run it "As Administrator" it will show an empty tree when trying to browse.

The OPC Server runs locally so I don't think it is a DCOM issue.

What I meant by "it fails to browse OPC items" is an empty tree without any error in this case.

Our OPC Client is 32bit application. The OPC server is also a 32 bit application.

Regards,

Michael

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06 Dec 2022 13:10 #11305 by support
Hello.

If the only difference in the conditions is running as Administrator or not, then you have a security configuration issue (COM/DCOM likely).
Have you tried running some other client in the same way as you are running yours (as Administrator)? What were the results?

In this last post, and also in the post that precedes it, I am always missing the actual description of the symptoms; this severely limits what can be concluded from such posts. When you wrote "it fails to browse OPC items", what does it mean? Was it giving some error? If so, what was the error? When you wrote (in the post preceding it) "the browsing didn't work", was it giving some error, or just blank list? If an error, what was the error message? Was it the error message you reported earlier, or perhaps the error I was seeing?

Regarding the differences in posts from 05 Dec 2022 20:58: Can you check in task manager what was the bitness of the process in these 3 cases? (32 or 64 bits)

I have also observed (although with the earlier version of the OPC server, not the one you instructed me to use) that the server installs a very old version of OPC Core Components (and only the 32-bit version of it). The newer version was more "silent" so I could not see what it was doing, but I suspect the same. I would suggest to uninstall OPC Core Components and then install the newest ones (opcfoundation.org/developer-tools/samples-and-tools-classic/core-components/ ; 64-bit version if it is 64-bit machine), to make sure that is not the cause.

Regards

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05 Dec 2022 20:44 #11303 by micham
Hi,

I noticed that when running the sample program:

F:\Program Files (x86)\OPC Labs QuickOPC 2022.1\Examples-NET\VBNET\VS2019\WindowsForms\EasyOpcNetDemo\bin\Debug\EasyOpcNetDemo.exe

As administrator, it fails to browse OPC items.

Our program is running as Administrator since it stop/start a Windows Service.

Thank you.

Michael

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05 Dec 2022 20:12 #11301 by micham
Maybe it is something that is related to the app.config file?

Thank you.

Michael

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05 Dec 2022 19:58 #11299 by micham
Hi,

Thank you for your answer.
I have also installed this OPC server and I was able to browse using this program:
F:\Program Files (x86)\OPC Labs QuickOPC 2022.1\Demos-NET\EasyOpcNetDemo\EasyOpcNetDemo.exe

But, when I tried running the sample VB project in Visual Studio (Debug mode):
F:\Program Files (x86)\OPC Labs QuickOPC 2022.1\Examples-NET\VBNET\VS2019\WindowsForms\EasyOpcNetDemo\EasyOpcNetDemo.vbproj

Browsing didn't work...

When I run the exe file from this folder:
F:\Program Files (x86)\OPC Labs QuickOPC 2022.1\Examples-NET\VBNET\VS2019\WindowsForms\EasyOpcNetDemo\bin\Debug\EasyOpcNetDemo.exe

The browsing did work.

Any explanation?

Thank you.

Mike

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05 Dec 2022 15:50 #11296 by support
I do not see any problem with your code.

The error comes from COM/DCOM and says the OPC server was not accessible at certain point ("The RPC server is unavailable."). I do not think there is anything wrong on the client or that the client can do much better. The error shows that there are moments on the system when the OPC server isn't quite ready.

There may be a higher chance of getting this kind of errors in QuickOPC applications like the one for which you provided the source below, because the connections to the OPC server "come and go", i.e. are made more frequently. It is possible to reduce the number of connections by specifying long "hold periods", or (but onloy if the app structure allows it) by "locking" the connection to a particular server by making a subscription to some item on it.

Regards

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05 Dec 2022 14:17 #11294 by micham
Hi,

Thank you for your answer.

I tried the EasyOpcClient on the customer's computer and I was able to browse for OPC items. After a while I got the error below but then I closed the client and open it again and I could browse OPC items again.

In our product the implementation is as you can see below. Please let me know if you see anything in the code or implementation that is incorrect.

Thank you.

Michael

Our code:
DaItemDialog1.ServerDescriptor.MachineName = server_properties.server_comp_name
DaItemDialog1.ServerDescriptor.ServerClass = server_properties.RealServerName
DaItemDialog1.MultiSelect = True
If DaItemDialog1.ShowDialog() = DialogResult.OK Then
SetChangeFlagToTrue(True) ' Jul-21-2021 V1.081
values = DaItemDialog1.NodeDescriptors
Cursor.Current = Cursors.WaitCursor
For i = 0 To (values.Count - 1)
Dim varType As VarType
szArrayLen = ""
szType = ""
ItemRemoved = False ' Aug-18-2021
Try
varType = easyDAClient.GetDataTypePropertyValue(server_properties.server_comp_name, server_properties.RealServerName, values(i).ItemId)
Catch opcException As OpcException
MsgBox("Error getting OPC-DA Item Data-Type(" + values(i).ItemId + ")!" + vbCrLf +
"MachineName=" + server_properties.server_comp_name + vbCrLf +
"ServerClass=" + server_properties.RealServerName + vbCrLf +
"CLSID=" + server_properties.server_CLSID + vbCrLf +
"OPC Server exception: " + vbCrLf + opcException.Message + vbCrLf + opcException.InnerException.Message, vbOKOnly + vbExclamation, "Error")
Exit For
End Try





Error message:
Type: OpcLabs.BaseLib.Browsing.BrowseException

Data:

HelpLink:

HResult: -2146233088 (0x80131500)

InnerException:

OpcLabs.BaseLib.Runtime.InteropServices.ExtendedCOMException (0x800706BA): The RPC server is unavailable.

+ This error can mean that specified machine name of the OPC server is incorrect, the machine is not reachable, or does not have DCOM not enabled.

+ The host name used is empty.

+ The machine name was ''.

+ The client method called (or event/callback invoked) was 'BrowseNodes'.

Data:

OpcLabs.EasyOpc.Implementation.ErrorEnhancement.Processed: True

OpcLabs.EasyOpc.Implementation.DAErrorEnhancement.Processed: True

ErrorCode: -2147023174

HelpLink:

HResult: -2147023174 (0x800706ba)

InnerException:

Message:

The RPC server is unavailable.

+ This error can mean that specified machine name of the OPC server is incorrect, the machine is not reachable, or does not have DCOM not enabled.

+ The host name used is empty.

+ The machine name was ''.

+ The client method called (or event/callback invoked) was 'BrowseNodes'.

Source:

StackTrace:

TargetSite:

XML Qualified Name 2: opcfoundation.org/DataAccess/:E_FAIL.0x800706BA

IsEmpty: False

Name: E_FAIL.0x800706BA

Namespace: opcfoundation.org/DataAccess/

Message: Problem browsing OPC Data Access (OPC-DA) leaves.

Source:

StackTrace:

TargetSite:
Attachments:

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05 Dec 2022 12:04 #11292 by support
Hello.

I get "Loading of configuration failed" when I try to open the file (SAIA_MERZ_OPCServerConffile\OPC_config.sbcfg) you attacched in the zip.



I tried my own new configuration instead (added one station to the blank config). With that:

- Browsing with Native client appeared to work fine (that is, I could see the node at the root for my station, and some sub-nodes underneath - I supposed that's how it should look like).
- Browsing with NetApi client did not work, and gave an error "OPC server has returned status: 'Test'. Problem details (status info): -
+ The client method called (or event/callback invoked) was 'BrowseNodes'.".

I suppose that the error given by NetApi client has to do with the fact that I am not using any real hardware. There is an IOPCServer::GetStatus which the NetApi client checks for, and when the returns this particular status, it reports it as an error. I admit this check should be more relaxed, the OPC_STATUS_TEST is not really a falire status.

So this is something that could be changed. However, it appears that your observations are not the same as mine, at least partially, so we need to align that first.
Questions:

1. You wrote that "we get an empty tree". Did you get any error indication, with the Native or NetApi client, too?

2. It seems weird to me that many times I instruct you to reconfigure the EnableNativeClient/EnableNetApiClient, you report that is had no effect. Can you elaborate on how precisely are you setting it? Are you doing it only inside your own application? If so, can you test the same from our tools such as OpcCmd, or Connectivity Explorer? (I can give instructions for that).

Thank you
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