Isolation is commonly used to deal with large common mode differentials. While
that can blow a 485 tranciever it does not happen alot unless there are vey
long cable runs or the cable runs between buildings. When running 485 for
distances of a few hundred feet connecting equipment powered off the same mains
transformer it's unlikely that enough differential will occur, but a quick
check with a voltmeter before connecting equipment is always a good idea.
So both comments are correct. In many cases 485 will run just fine without
isolators, but some applications definitely require isolation. I build 485
isolators, but they are rarely tested to their limits. Often the isolation is
more of an insurance policy-it ensures that a single device cannot take down an
entire network segment.
Javid
----- Original Message -----
From: Dean Hedin
To: Enhanced Machine Controller (EMC)
Sent: Sunday, February 03, 2008 9:15 PM
Subject: Re: [Emc-users] Modbus RS-485 Transceiver
At 6 bucks a pop, buy 2.
Seriously, I worked with 485 at a previous job and I never blew out a non
isolated converter.
Of course it might depend on what your doing I guess.
----- Original Message -----
From: [EMAIL PROTECTED]
To: Enhanced Machine Controller (EMC)
Sent: Sunday, February 03, 2008 8:42 PM
Subject: Re: [Emc-users] Modbus RS-485 Transceiver
Good advice is never to buy non-isolated converters.
You will replace them regularly if you do.
This does not seem to be isolated.
Kirk Wallace wrote:
On Sun, 2008-02-03 at 03:06 -0500, Dean Hedin wrote:
Interesting if you have the time..
But for six bucks and free shipping...
http://www.dealextreme.com/details.dx/sku.6040
Obviously, I didn't look hard enough when went looking for these. Thanks
for the link Dean.
----------------------------------------------------------------------------
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
----------------------------------------------------------------------------
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
------------------------------------------------------------------------------
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
------------------------------------------------------------------------------
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
