Hello,
can you please help me to get a paragraph which explains RS-485 adaptation with computer and how we should use USB converter to establish communication.
thank you in advance.

 

You buy a USB/RS-485 adapter.

I prefer those with an FTDI chipset, because FTDI registers their products with Microsoft which makes installation on the PC easy, I've never had to load a driver because Windows has the driver for FTDI.

A USB/RS-485 adapter installs on a virtual COM port. You need to find the COM port number to use in your application. The virtual COM port is found in Control Panel > Device Manager > Ports.

Enter the COM port number in the application that uses RS-485 communications.

Assuming it's half-duplex 2 wire communciations, if there's a 3rd wire for signal ground connect signal ground on both ends, but some devices only supply the 2 connections for the driver lines.

Be aware that there is no enforced 'standard' for labeling RS-485 driver lines. Connections are theoretically supposed to be (+) to (+)/(-) to (-) or A to A/B to B, or Rx+ to Tx+/Rx- to Tx- or whatever, but some vendors define the driver functions the opposite of the others. Connecting the driver lines backwards will not damage the driver lines, but communications will never happen. If you can't get comm up and running try swapping the driver lines on one end.

 

Hello ,
Thank you for your help sir that really helped and I managed to work with it it gave excellent results ! Thank you again

 

Hello ,
Thank you for your help sir that really helped and I managed to work with it it gave excellent results ! Thank you again

Here a circuit for Modbus RTU with FT232RL and Optokopplers :
Best Regards [email protected]

 

Here a Pic of the Board:

 

Here a circuit for Modbus RTU with FT232RL and Optokopplers :
Best Regards [email protected]

Hello,
Thank you so much for your help it's very interesting and helpful!