The ACCES I/O M.2-COM-4SM features high performance 16C950-class UARTs. This card has 4-Ports and each port is capable of communication speeds up to 921.6kbps in RS-232 and has 128-byte deep transmit and receive FIFOs. Large FIFOs protect against data loss in multitasking operating systems, reduce CPU utilization, and improve data throughput, while reducing or eliminating inter-character or inter-packet pauses. The advanced integrated circuit with pre-scalar supports a wide variety of custom baud rates, and any rates not otherwise achievable can be supported via a custom factory-installed crystal oscillator. RS-232, RS-422, or RS-485 can be software selected, per port, and the selection is stored in non-volatile memory for future use. If you don’t need that much flexibility you can order versions with only RS422/485 or even pure RS232. The RS232 ports provided by the card are 100% compatible with every other industry-standard serial COM device, supporting TX, RX, RTS, and CTS. RS422 mode uses the same transceivers as the RS-485 specification, allowing perfect 4-wire RS-422 and RS-485 compatibility – and the device supports full-duplex RS-485 4-wire.