Hello, the LOGO! Software Comfort has a monitoring mode ?

Yes.

In the menu in the uppr side of the workspace ther is a symbol for monitoring.

But its not perfect, If you have make a very little setting of a block or something LOGOSoft says that the programms are different, so you have to upload the programm again.

The simulation mode of Logo Softcomfort is perfect. It works like a mirror of that is happens in a circuit program. If you want to change something in the program you must first exit to the simulation mode, do your modifications and after goes to simulation mode again.

If you have some error information from the software, certanly there is a problem in your circuit.

In the other hand, see bellow the work área, on the right size. May be appears a icon beside the Logo icon. By clicking you can see error messages. See attachament.

I hope it helps you