Advantech RSB-4680, User Manual

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RSB-4680 User Manual 36
3.4 UART
The Android/Linux UART/serial port access from user is through the tty-devices. The
tty-devices have different names depending on UART driver on different board.
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 Device Node Remark
UART0 /dev/ttyS0 for BT Data
COM1 /dev/ttyS1
COM2 /dev/ttyS2 Debug Port/RS232
COM3 /dev/ttyS3
COM4 /dev/ttyS4 Support RS485
COM6 /dev/ttyUSB0 USB to UART
COM7 /dev/ttyUSB1 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)