Known Problems

When using the RS485 of the given CAN/Serial cape, there is a problem in using the RS485 transceiver. Because the Linux driver cannot switch back and forth between transmit and receive mode, applications may not work as expected.

Detailed description: The serial driver of the BeagleBone Black(OMAP) does not support the transmit/receive switching (DE/RE or RTS) necessary for the RS-485. Instead, it has an RS485 mode that uses a permanently assigned GPIO pin for checking the DE/RE lines and it has a modified structure (serial_rs485 struct) compared with the serial standard driver. You have to use ioctl on the corresponding devtty file in order to place the serial driver in RS-485 mode and tell it which pin it needs to use. Moreover, you have to take care of the multiplexing of the pin in GPIO mode.