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???
06/11/09 17:11
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 		 #166020 - RS485 Converter
Responding to: ???'s previous message
Hi Joseph,

My device takes data from USB port and converts it to RS485. The RS485 side is optically isolated from USB side. And yes, it has a connector for RS485 line and I connect a short RS485 cable while testing the communication.

The device was initially designed as self-powered. After lots of tests I converted the design to bus-powered. Changing from self-powered to bus-powered hasn't improved its EMI performance, at least I couldn't see a noticeable change.

The only thing that made a serious improvement in EMI performance was using a shielded USB cable instead of a shield-less one. (The funny thing is that I was thinking that I'm using a shielded cable from very beginning, until I actually measured it!)

A picture of my device can be found here:
http://www.8052.com/forum/read/165885

List of 30 messages in thread
TopicAuthorDate
FT232R USB to Serial            01/01/70 00:00      
   Something silly ?            01/01/70 00:00      
      Capacitive Coupling            01/01/70 00:00      
         Ideas            01/01/70 00:00      
         there is always SOME coupling...            01/01/70 00:00      
   crash and reset the USB connection            01/01/70 00:00      
      Very unlikely            01/01/70 00:00      
         PC USB crash            01/01/70 00:00      
            Isolated hub?            01/01/70 00:00      
         PC Isolation?            01/01/70 00:00      
   just blame the chip.            01/01/70 00:00      
      Please see my other post with image (nt)            01/01/70 00:00      
   is connector grounded on Your side?            01/01/70 00:00      
      Huh?            01/01/70 00:00      
         yes            01/01/70 00:00      
            Floating the end of the cable shielding            01/01/70 00:00      
      Was using wrong cable            01/01/70 00:00      
   More information            01/01/70 00:00      
      Hmm            01/01/70 00:00      
      isolation            01/01/70 00:00      
   Update...            01/01/70 00:00      
      USB and RS485            01/01/70 00:00      
         could this be it            01/01/70 00:00      
            Tested both self-powered and bus-powered            01/01/70 00:00      
         RS485 Converter            01/01/70 00:00      
      el.circui?            01/01/70 00:00      
      re: why?            01/01/70 00:00      
         USB 1.1            01/01/70 00:00      
            re: USB 1.1            01/01/70 00:00      
               popular culture            01/01/70 00:00      

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