I have been running the PLC Editor in Windows 10 v1809 to compile and run a simulation of a PLC Ladder Logic program. I duplicated the project, and edited the ladder logic to use additional blocks (CTUD, CTU).

Initially I made some errors in selection of input and output variable types -- I discovered that the standard counter blocks CTU, CTD, CTUD used int variables instead of uint variables. I resolved those errors, but the PLC Editor still would not run the simulation.

I installed all OS updates, restarted the OS, then had the PLC Editor load the original PLC ladder logic project which is still running in OpenPLC on an Raspberry PI. When I have the PLC Editor run the simulation, I see the same error:

Compiling IEC Program into C code...
Extracting Located Variables...
C code generated successfully.
[CC] plc_main.c -> plc_main.o
[CC] plc_debugger.c -> plc_debugger.o
py_ext :
[CC] py_ext.c -> py_ext.o
[CC] Config0.c -> Config0.o
[CC] Res0.c -> Res0.o
Linking :
[CC] plc_main.o plc_debugger.o py_ext.o Config0.o Res0.o -> Power_Cycle_v1.2.dll
Successfully built.
PYRO connecting to URI : PYROLOC://
Exception while connecting to 'LOCAL://': connection failed
Connection failed to LOCAL://!

What else can I try?
What should I look at?
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It seems that the editor is failing to connect to Beremiz service. Check if the beremiz service is running on the icons next to the clock at the taskbar. If it is running try killing it on the task manager (kill all processes running Python) and try again
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Killing the Python.exe processes did not work the first or second time.

I remembered that since I last used the PLC Editor simulator, I had installed some software (Apache Tomcat, ...) that installed some services and set them to Auto start. I stopped those services, and set them to Manual start.

The PLC Editor gave the same error when simulating the ladder-logic project that worked a few months ago. When it spawned a second Python.exe process, both Python.exe processes did not seem to consume very much CPU, but things kept running for a very long time until the compilation completed and the error showed up in the log.

I restarted the PLC Editor again, then restarted and opened the Hello World project. The simulator worked on that. Now the PLC Editor works on the ladder-logic project from a few weeks ago, as well as the newest one that I created.

It is almost as if the errors from my mis-configured ladder-logic changed some sort of state that was remembered, perhaps in a file somewhere.

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