I've toyed with a gaggle of simulators and this one is one of the better ones I have found, glad to see you have resurrected and it lives on.
One issue that I notice that could be handled better is when testing in Modbus RTU mode, if the USB cable is unplugged, the module starts chucking with the error shown in the screenshot. It would be nice if when we plugged back in, the program would recover and perhaps the log would not be spammed during the disconnect. Right-now we have to restart the program to recover.

I've toyed with a gaggle of simulators and this one is one of the better ones I have found, glad to see you have resurrected and it lives on.
One issue that I notice that could be handled better is when testing in Modbus RTU mode, if the USB cable is unplugged, the module starts chucking with the error shown in the screenshot. It would be nice if when we plugged back in, the program would recover and perhaps the log would not be spammed during the disconnect. Right-now we have to restart the program to recover.