While providing compatible software functions, there are two different hardware versions due to IC short supply, and they will be delivered randomly, we don't know in advance which one will be delivered for your order. Please make sure you don't mind it before placing order. ^^ Modbus is not supported M0 series 32-bit ARM processor, fast speed, high efficiency. 10/100M Auto-MDI/MDIX ethernet interface, regardless of cross-over or straight-through cable ^^ Auto-reconnecting, provides a reliable TCP connection ^^ Supports time-out reboot (no-data reboot), configurable reboot time ^^ Flexible serial port data framing, allows kinds of customized packeting