Try with changing the parameter 'UseDTR' in the Arduino model. Some boards like the Arduino Leonardo need this parameter set to 'true', other boards need to be set to 'false'.

In the Firmata web page ( http://firmata.org/wiki/Main_Page ) you can find the 'FirmataTest' program. You can use it to check if your board is working properly. If the board does not work with 'FirmataTest' it may not be a problem with the ModelPlug.

Hi Bro. Hope you are well. I am facing the EXACT same problem. But I do not have an Uno :P

Were you able to make it work on 2560?

Anxiously waiting for reply!!

Thanks

Thanks for your fast reply! I am using a trial-version of SystemModeler 4.1. for my work with ModelPlug. And I hope that it should not matter that I use a license for 30 days. The SystemModeler is running under the operation system Windows7. Of course I tried to solve my problem with rechecking the COM-port and the other ports. I also synchronized it with real-time. I verified all of your troubleshooting hints from the "GettingStarted" tutorial. Everything sould be fine. The next step I want to do is using an Arduino Uno instead of an Arduino Mega 2560, to make sure that the problem is with SystemModeler. I am quite sure, that my Arduino Mega 2560 is working correctly, because I worked with it in the last few days.