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Author Topic: FT2232HQ adds extra one byte  (Read 19637 times)


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FT2232HQ adds extra one byte
« 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?

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Re: FT2232HQ adds extra one byte
« Reply #1 on: March 21, 2024, 03:32:52 pm »


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.

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