RS-485 port for Modbus comunication with RTS toggle via SW on Lattepanda sigma

Hi,

we are testing your LattePanda Sigma with Windows 11 OS for Modbus communication using RS-485 interface but some problems occurred.

We toggle the RS-485 switch from RS-232 on the back of the board to test the communication with one Modbus device on COM1 using the internal pin.

We have to change our normal Modbus console application because it doesn't work without toggle on RTS to transmits and receive a message.

Moreover, we have to put a very little timespan (10ms) between port.Write and disable RTS to have the good response from our device (see below).

Normally, we have a lot of devices on the same bus that we send a request every 500ms and we don't use stopwatch system with delay depending on the message in a release version because it is not optimized. 

Do you have any idea to solve the problem by BIOS settings without using RTS toggle via SW?

I checked the BIOS and I find only the Console Redirection (not EMS) settings disable (see below). Is this our setting to enable? Is there some way to enable it?

Our actual BIOS version is LP-BS-WTADLC1R210-16G-D and on your website it's the last one.

Thanks in advance for the cooperation.

Best regards,

A.C.