Advantech EPC-R4680, User Manual

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EPC-R4680 User Manual 22
3.4 UART
The Android/Linux UART/serial port access for the user is through the tty-devices.
The tty-devices have different names depending on the UART driver on different
boards.
RS-485 uses half-duplex communication, which means that one medium is shared
for transmitting and receiving data. Therefore the system needs to control the RS-
485 transceiver's transmit mode. Usually the UART RTS signal is used to switch the
transmitter on and off.
The COM2 defaults to the debug console, which can be switched to RS232 by pin-
header, short circuit CN18 1 and 3.
COM Name HW Schematic Device Node Remark
NA UART0 /dev/ttyS0 for BT Data
COM5 COM1 /dev/ttyS1 RS232
COM1 COM2 /dev/ttyS2 Debug Port/RS232
COM6 COM3 /dev/ttyS3 RS232
COM2 COM4 /dev/ttyS4 Support RS485
COM3 COM6 /dev/ttyUSB0 RS232 (USB to UART)
COM4 COM7 /dev/ttyUSB1 RS232 (USB to UART)
COM CN18 (1-3)
CONSLE CN18 (3-5)
COM4 RS485 Impedance On CN18 (4-6)
COM4 RS485 Impedance Off Cn18 (2-4)