Can i use the USB port of P1, instead of the Tx - Rx of UART1 port, to communicate with the Modbus slave unit? Attached is a block diagram of interfaces. In Modbus Master library the UART Tx - Rx and the D7 are used. I suppose that the same library could be used and for the slave (server) with some modifications? USB setup examples are included in Particle Docs-->Reference-->Firmware-->Serial. Do you think that i could have troubles with USB?