RS-485 adaptation with a PC
- Thread starter Imy7
- Start date
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.
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.
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Hello,
Thank you so much for your help it's very interesting and helpful!
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