FTDI Community

General Category => Discussion - Hardware => Topic started by: mnecetinkaya on March 21, 2024, 01:18:18 PM

Title: FT2232HQ adds extra one byte
Post by: mnecetinkaya on March 21, 2024, 01:18:18 PM

Hi everyone,

I have a problem like I mention in title shortly. I designed a board to communicate between pc and a device which use RS485. I can communicate but every time receive a data it comes with a FE or FF byte as prefix. I'm using FT2232HQ with ADM3485EARZ-REEL7 on my board. Then I used USB-COM485-PLUS2 and I compared the waveform of the two converters. Even though the waveforms are same, I did not receive any extra byte while using USB-COM485-PLUS2. I wonder if I get schematic of COM485-PLUS2? Or does anyone have an idea about that situation?

Title: Re: FT2232HQ adds extra one byte
Post by: FTDI Community on March 21, 2024, 03:32:52 PM

Hello,

The extra bytes may be due to lack of biasing on the RS485 transceiver. If you could email into support1@ftdichip.com we can share the RS485 biasing schematic that will be able to help you.

Best Regards
FTDI Community