Invert UART RTS polarity to drive RS485 Converter

[jethro]

Hi all,

 

I'm trying to use an Orange Pi PC Plus to drive an RS485 serial converter and ultimately talk Modbus to a sensor device.  I have managed to get flow control enabled on the port, but the polarity of the RTS signal is active LOW, whereas the converter I have requires active HIGH. 

Is there any way to invert the polarity of the RTS pin for the UART? I think it can be done via ioctl call in C programs, but I need this applied at a system level to be compatible with some third party software.

 

Thanks in advance!