J1708 - J1587 multiple ECU simulator is a platform aiming to aid the professionals who are developing hardware for buses and other commercial vehicles. It can simulate 3 ECU's at a time, which broadcasts 5 adjustable parameters. When parameters pass below or above a threshold value, simulator starts to broadcast malfunction message. DTC's interact with each other and transport protocol is implemented for broadcasting large messages. These features allow the developer to work in a more strictly protocol compliant environment.