I am running m90/91 unitronic plc in 4 thermoforming machines. Up til now I have never had a problem accessing the controller with my laptop. Today I am unable to access any of the controllers! I am getting the following error. Unable to open com1. It says to check communication settings and check wire and to reboot. This has now happened on 2 seperate computers. I can't get in to dump program and I am stuck as I now need to get a new machine up and running. Help Please.