OPC DA with schneider PLC but have ComSubscription error

Dear All,

I try to connect to OPC DA with schneider PLC, but have ComSubscription error in log.
Local Server seems to be ok.
OFS client is able to read write data.
Ignition the server status is “connected”, but with OPC Quick Client I am not able to read any tag.
I log I can read(see below).

Thanks a lot for help…

at com.jniwrapper.win32.com.impl.IUnknownImpl.invokeStandardVirtualMethod(SourceFile:762)

at com.jniwrapper.win32.com.impl.IUnknownImpl.invokeStandardVirtualMethod(SourceFile:741)

at com.jniwrapper.win32.ole.impl.IConnectionPointImpl.advise(SourceFile:93)

at com.inductiveautomation.opccom.wrapper.subscriptions.DataChangeDispatcher.advise(DataChangeDispatcher.java:83)

at com.inductiveautomation.opccom.wrapper.subscriptions.COMSubscription.oleloop_updateGroup(COMSubscription.java:775)

at com.inductiveautomation.opccom.wrapper.subscriptions.COMSubscription$Connector.internalRun(COMSubscription.java:823)

at com.inductiveautomation.opccom.wrapper.OleJob.run(OleJob.java:48)

at com.jniwrapper.win32.MessageLoopThread$ThreadSynchronizedAction.run(MessageLoopThread.java:620)

at com.jniwrapper.win32.MessageLoopThread$LoopThread.run(MessageLoopThread.java:562)

Is there a ‘Caused by’ portion of the log? That usually provides a clue as to what’s going on.

Is there a “best way” to use classic OPC DA with ignition?
How to add an item from a server in ignition?
In OPC Expert we can see value with correct value, but in ignition we only see “Value null”


From the Knowledgebase:


Thanks you for the link.
Adding the OPC Core Components x64 had no effect. the settings seems to be fine, but inside the Ignition Designer the Value is always “null”, there is no error, but no data also…

any help would be appreciated,

Right click on the MW0 and int_siemens tags and select Tag Diagnostics then highlight the Last Error Cause and post the pictures here…
That percent sign in tag path is suspicious to me…

Thanks you for the answer.
the percent sign is ‘typical Schneider’ (see OPC scout tag in the picture). Tag Diagnostics give no error, all is fine, but no data…

How did you created this MW0 tag in Ignition?
Did you write that OPC Item path your self?

Yes, the tag has been added by hand (it seems not to be possible to discover OPC DA items).
We are able to discover the servers (siemens and Schneider) but not the tag(s).

Then it won’t work…
You MUST add the tags from OPC Tag browser and drag them to your tags.
If OPC Tag browser can’t see the tags in the OPC server, then also adding them by hand doesn’t work.
What about Ignition OPC Quick client (at he bottom) on the web configuration page?
If you can’t see the tags there, then your connection to the OPC server doesn’t work…

If I drag an drop a tag from exposed #specific I get the same behavior (the data is “null”)…

Now look at the Logs on the Ignition Status page…
There must be some errors…

Yes error are displayed but the meaning?

It looks like your Schneider doesn’t support DA3. Show your OPC connection configuration page…

The com error says E_ACCESSDENNIED but where can we check/change this?

That means that you DCOM setting in Windows are not set correctly.
@JordanCClark gave the link where it is described how to set DCOM…
Yes, it is a pain in the a… , I know… been there, done that…
DCOM sucks…

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Thanks a lot for your help:
I will try again this settings, but for me I found nothing with “strange settings” in DCOM…


I suggest looking on google for OPC DA access denied.
There is also this: OPC COM inside the Ignition manual.
I’ve learned (the hard way) over the years that no two cases are alike involving DCOM. So there are no definite instructions for every case…
Last month I spend two days to connect Ignition gateway to 8 old PCs with mainly ABB OPC DA servers. And in the end, most problems were with the DCOM settings on the PCs side.


The OPC-COM Tunneler module may help as well. You would have to grab it from the v7.8.5 download archive, but it should work for 7.9.x as well.

Note: Tunneler will be available again starting with 7.9.11: https://inductiveautomation.com/downloads/beta

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