The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "Ken Taylor"
Subject: Re: RS232 - daisy chain - switch
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 25 Nov 2002 19:57:18 +1300
NNTP-Posting-Date: Mon, 25 Nov 2002 19:55:53 NZDT
"Peter Bennett" wrote in message
> On Sat, 23 Nov 2002 16:30:17 +0100, "Nikolaj Christoffersen \(remove
> XPKZ\)" wrote:
> >I have a PC (windows) communicating with 36 hardware units through RS232.
> >The 36 units are daisy chained. The control program running at the PC
> >every unit a number.
> >Does anybody know if it is possible to get some sort of RS232 switch
> >can connect my 36 units in 4 groups of 8 and still have my control
> >and see all 36 units at one time. My problem is that communication to
> >35 is to slow.
> Sounds like you have each unit repeating the messages for the
> downstream units.
> I recently did a system with a dozen daisy-chained devices on RS-232 -
> Each device had a switch (which it controlled when it wanted to talk)
> that connected the input of its "to PC" MAX232 converter to either its
> own output, or to the input from the downstream units. Each unit
> simply tapped off PC->device path, on the TTL side of the MAX232s.
> This way, there was only a few microseconds of difference in timing
> between the first and last device - just gate and wiring delays - as
> the signals were not repeated by each device. This system requires
> that the devices only talk in response to a message from the PC.
> Peter Bennett, VE7CEI
That sounds very elegant, but it is *way* easier to use RS-485, which is
made for this. I do exactly what the OP is talking about using this
interface instead. I use small self-powered RS485-RS232 converters where
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup