Raspbian Software Serial Implementations; Rs-485 Control Commands; Xsmn - Rs-485 Tx-Enable Mode (*) - Sferalabs Strato Pi Base Advanced Configuration Manual

There is a 5 seconds character timeout when receiving commands. If a character is not
received for 5 seconds since the previous character, the command buffer will be reset, and
the PIC will start looking for a new "X" ASCII command header character.
All commands use upper case characters only. Lower case characters won't match.
The configuration parameters corresponding to commands marked with (*) are retained
only until the next power-cycle, unless persisted in memory. If not persisted, the
parameters will be reset to the original factory defaults, or to the previously saved user
configuration. Refer to the "Permanently saving the current configuration" chapter for more
details.

Raspbian software serial implementations

There are a few software serial Linux modules implementations for Raspbian. An open-
source module is available on GitHub at: https://github.com/sfera-labs/soft_uart
After the module is compiled and installed, it can be loaded and configured to use the
appropriate GPIO pins, for example:
sudo insmod soft_uart.ko gpio_tx=13 gpio_rx=19
To load the module automatically at boot, add the line:
soft-uart
to /etc/modules, and create a new file /etc/modprobe.d/soft_uart.conf to set the module
options, with the appropriate GPIO numbers, for example:
options soft_uart gpio_tx=13 gpio_rx=19
The protocol is human readable, you can test it with minicom or any other terminal
program:
minicom -b 1200 -D /dev/ttySOFT0
On a Raspberry Pi Model 3 B+ and Raspbian, it has been tested successfully at speeds
up to 19200. Data transfer becomes unreliable at or above 38400.
A different software serial implementation is the pigpio Python module: http://abyz.me.uk/
rpi/pigpio/python.html

RS-485 control commands

XSMn - RS-485 TX-Enable Mode (*)

Set the TX-Enable operations mode.
5 Strato Pi Logic Controller