The system is used for the management of a radio amateur station. I can't use just one microcontroller because each Nano manages a different piece of equipment, an antenna switch to one side and a linear amplifier to another side. The Application2 manages via another USB port the radio exciter and is written by the radio manifacturer, so I can only set the COM port. The Application1 was written by me in VB and act as hub. The speed is important because involve protection functions.