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Old December 24th, 2017, 11:07 AM   #1
sparkie
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A bit hung up with OPC

So I'm running a couple of VM's in VMWare.

VM1(Windows 7 Ultimate): RSLinx Classic 3.74 with RS Emulate 500 and I have an OPC topic set up for the processor. I can connect locally with the OPC Test Client.

VM2(Windows 10): After setting up a connection, I could browse to connect via automation direct Point of View and I can browse the Topic, and see the Online Folder, but nothing past that, making me think something is preventing a remote host from seeing the tags. I can browse the OPC server with National Instruments OPC Client, and read the tag value, but the subscription fails with an unknown RSLinx error.

Host OS(Windows 10): Tried to connect via the National Instruments client and I can't see either VM.

I can browse all machines with Netbios and see each file share. I have also temporarily disabled private firewalls. All virtual machines are on a bridged network setup and seem to be functioning fine, though I could not browse the VM's from the host machine with host-only networking enabled.

Not being able to browse past the online folder, and getting an unknown rslinx error makes me think the two are related.




Last edited by sparkie; December 24th, 2017 at 11:17 AM.
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Old December 24th, 2017, 11:54 AM   #2
thingstodo
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I am not sure about the rules now, but to have non-rockwell software (browse) access OPC tags from RSLinx in the past, I had to buy RSLinx Gateway. The same installation as RSLinx lite, but licensed to share the data.

Then I had to set up the DCOM settings on each of the computers to allow for the connection and sharing of data. I believe I ended up using the same login account and credentials on both computers to get it running.

And the last part I can remember is setting up read permissions and write permissions inside the registry, where the Matrikon Datamanager looks to get it's login credentials for accessing data from RSLinx. I don't think RSLinx used the registry.

If you are putting in a new system, I would recommend paying someone to install it and get it working before they deliver it. To have it work as advertised, that's what I would do if I had it to do again. But I'd use OPC as a last resort. It is the least reliable system that I have on my site. And that's saying something!

OPC was supposed to be the solution to all communication problems. Get a server from your PLC vendor, use any client you want to. I've never gotten the system reliable. It's been 14 years since our first installation and I move more stuff off OPC and onto something else each year. If I had a way to communicate between ABB switchgear and ControlLogix, I would have thrown out the OPC server 2 years ago. Along with it's unstable status reporting, frequent crashes, over-writing data in random parts of my PLCs, flat-lining trends .. you get the idea.

To be clear, I have not used OPC version 2. None of the vendors that I use have servers for it so I have not investigated it. Version 2 may be what version 1 was supposed to be.

Our PI system seems to be able to gather data from our various OPC servers - not sure if they have problems or not. I don't support that system so I don't hear about issues
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Old December 24th, 2017, 12:34 PM   #3
sparkie
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Thank you. This is more meant for a simulation project so I can try out some different HMI's before I make a decision on which package to go with. The customer is wanting some integration with some other data tracking software. Normally, I would would be connected directly to the PLC, but I'm just using the simulator right now. I wonder if there is a way to tunnel a serial port to the emulator.
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Old December 25th, 2017, 06:43 PM   #4
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I never could get call-backs working. It has something to do with the windows 7 VM going to the windows 10 VM so I gave up and installed POV on the win7VM. It is just for a demonstration at this point.
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Old December 27th, 2017, 03:41 PM   #5
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It is most likely DCOM settings. Since it is VM's, and simulation, you can open DCOM up as wide as possible. However, Microsoft recently made security changes for RPC calls which is what a remote OPC DA call is. That could be blocking you Datachange events from being updated back to the client. Overriding that is a much more difficult project.

You should see messages posted in your OS's System and Program event logs of this is happening.
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Old December 27th, 2017, 05:28 PM   #6
sparkie
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Quote:
Originally Posted by Fred_Loveless View Post
It is most likely DCOM settings. Since it is VM's, and simulation, you can open DCOM up as wide as possible. However, Microsoft recently made security changes for RPC calls which is what a remote OPC DA call is. That could be blocking you Datachange events from being updated back to the client. Overriding that is a much more difficult project.

You should see messages posted in your OS's System and Program event logs of this is happening.
I did, in fact, check the system log. I can't remember the exact message, but it had to do with a DCOM reply timeout from Windows 7 to Windows 10. The Windows 10 computer could get the data from the Windows 7 OPC server just fine, however the server could not complete the callback.

I didn't know that RPC handled the DCOM calls, I did however think that there was an issue with windows 7 versus windows 10 dcom setups, but I'm not quite sure how to go about troubleshooting the callbacks. If anyone wants to request more in-depth information I would be happy to post it up and try to get callbacks functioning, as I would like to communicate from my windows 10 host to the windows 7 VM via OPC as well so I can play with AdvancedHMI.
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