PLC Variables Not Visible in "All Symbols" When Target is Remote in TwinCAT

Question

I am working on a project in TwinCAT 3 and encountering an issue where I can't see my PLC variables in the "All Symbols" view when the target is set to a remote device (not local). Everything works fine when the target is local, but once I switch to a remote target, the variables seem to disappear from the list.

Here's the setup:

• TwinCAT project with a minimalPLC program.
• When using a local target, all PLC variables appear in the "All Symbols" view.
• As soon as I change the target to a remote PLC (set via IP), I can no longer see the PLC variables.

What I've Tried:

• Verified that I am connected to the remote target (confirmed in the bottom-right status bar of TwinCAT).
• Downloaded the PLC program to the remote target and ensured it's running.
• Checked firewall and network settings (confirmed that the target PLC is reachable via the network).
• Ensured that symbol export is enabled in the PLC settings.
• Made sure the remote PLC is in RUN mode, not CONFIG mode.

Additional Info:

• The project builds and runs fine on the local target.
• I'm using TwinCAT 3 and connecting to a remote target PLC via an IP address.

Is there something I'm missing in the configuration when switching to a remote target?

How can I make the PLC variables visible in the "All Symbols" view when working with a remote target?

Answer 1

The issue likely arises from misconfigured symbol settings when targeting a remote PLC. Here’s the solution:

1. Open TwinCAT HMI Server Configuration.
2. In the ADS tab, ensure the remote PLC is correctly selected as the target in the AMS Net ID dropdown.
3. Click Accept to save changes.

This should ensure the symbols appear in "All Symbols."

For better understanding, I’ve attached a GIF file as a step-by-step guide.

Answer 2

What you're seeing is unfortunately as expected and I don't know of a neat solution.

The following happens:

1. You make a PLC project and run it locally.
2. You make an HMI project and run it locally. The HMI is configured (by default) to connect to a local PLC.
   • You could now upload the PLC and HMI projects to a remote target and they should work. The remote HMI will connect to the PLC locally, same as on your PC. The fact that the local is now different doesn't matter.
3. After the PLC is running remote, you want to modify your HMI. The unchanged HMI project is still pointing to a local PLC connection, but that fails because no PLC is running on your PC anymore.

Now you could alter the HMI project to use the remote target instead. HMI live view and ADS variable listing will work again.
But when publishing the project to the remote target will cause problems, because then the remote target will be trying to connect to a remote target, instead of locally where the PLC is running.

Conclusion: run the PLC locally again to develop the HMI or modify the HMI to use a remote target too (without forgetting to revert this when publishing).