#This is the Raspberry Pi fork of libmodbus () with GPIO rx-tx functionality RS485 chips
#When it should be used :
If you're using an UART to RS485 conversion chip like 75176 or anything similar and using one of the RPi GPIO to switch rx - tx functionality of the chip.
In addition to standard libmodbus API, addtional APIs are included to support GPIO based rx-tx switching
#Additional APIs :
modbus_enable_rpi : Sets an enable Rpi integer in ctx data structure.
modbus_configure_rpi_bcm_pin : Configures GPIO BCM pin to be used for rx-tx switching
modbus_rpi_pin_export_direction : export configured GPIO, configures it as an output.
modbus_rpi_pin_unexport_direction : unexport configured GPIO, configures it as an input.
#Usage :
#While initializing :
modbus_enable_rpi(ctx);
modbus_configure_rpi_bcm_pin(ctx,18); // configures BCM pin # 18 for switching
modbus_rpi_pin_export_direction(ctx); // exports configured BCM pin #
#While clean up :
modbus_rpi_pin_unexport_direction(ctx); //unexport configured BCM pin #
#Examples
See test.c in rpi-test folder for template.