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List:       rxtx
Subject:    Re: [Rxtx] RS-485 echo processing
From:       John Charlton <j.d.charlton () ieee ! org>
Date:       2004-09-15 15:50:26
Message-ID: 200409151150.26175.j.d.charlton () ieee ! org
[Download RAW message or body]

Trent and all:

I did some more experimenting with enableReceiveThreshold() and 
enableReceiveTimeout() and have a combination that works now to consistently 
read the RS-485 echo without missing transmitted packets.  Just setting 
enableReceiveTimeout() alone does not seem to work because the read(buf, 0, 
len) returns before the timeout set in enableReceiveTimeout().  I tried 
various timeout settings up to 10000 ms and read(buf, 0, len) still returns 
prematurely before timeout is reached and before len characters are received.  
The code in the attached tgz file works consistently.  If I use both 
enableReceiveThreshold(len) and enableReceiveTimout(500), no packets are 
lost.

With a bit more testing, I am able to pickup the echo with timeout setting 
down to enableReceiveTimeout(10).  It does timeout with 
enableReceiveTimeout(1) which in encouraging since I am transmitting at 9600 
baud for this test and it should timeout at 1msec.

Thanks for the help,
--John

["echotest.tgz" (application/x-tgz)]

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