Communication Protocol Between the Host (PC) and the USB1287 Gateway

The SH1 protocol is built to be tested/invoked from a terminal, that's the reason for all the ASCII characters. The package uses a:

• Fixed character as preamble to indicate start of package

• Destination address byte

• Source address byte

• Command byte

• Size byte

• Data payload

• Simple checksum byte, the sum of previous bytes

• Carriage return character

The package is minimum 7 bytes and maximum 262 bytes in size. DATA is transmitted only if NBYTES is nonzero.