Re: [foxboro] Modbus Multidrop

We have quite a few multidrop setups going to Integrator 30's.  I have
used the Black Box ME837A, RS-232/RS-485 copper line drivers with good
success.  They are also optically isolated to help eliminate grounding
problems.
http://www.blackbox.com/Catalog/Detail.aspx?cid=3D381,1452,1465&mid=3D111=
9 =20

On a recent project I switched to ME540A fiber line drivers.  These
devices will connect to a copper RS-232 or RS-485 devices and then do
the multidrop on the fiber side.  Because the multidrop is done between
the modems it is a lot easier to deal with devices that don't handshake
well.  They are a little more expensive but worked so well that I am
planning to stick with this setup in the future.=20
http://www.blackbox.com/Catalog/Detail.aspx?cid=3D381,1452,1470&mid=3D118=
6=20

Regards,
Terry

Terry J. Deo
Infineum USA, L.P.
Bayway Chemical Plant
Linden, New Jersey 07036
Ph: 908-474-6179
Email to: terry.deo@xxxxxxxxxxxx


-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Johnson, Alex P (IPS)
Sent: Wednesday, September 05, 2007 8:51 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Modbus Multidrop

I've normally used Black Box. Their free technical support is awesome.
Just call them and they will tell you what you need.

www.blackbox.com

From their website: http://www.blackbox.com/Tech_Support/Index.aspx

   Telephone:
   724-746-5500
   Answered in 20 seconds or less!

   Fax:
   800-321-0746
   Answered in 15 minutes or less!

   e-mail:
   Send an e-mail.
   Answered in 15 minutes or less!

   Online:
   Talk to Tech
   Answered in 20 seconds or less!


Who says there is no money in hardware? :)


Regards,

Alex Johnson
Invensys Systems, Inc.
10900 Equity Drive
Houston, TX 77041
713.329.8472 (voice)
713.329.1700 (fax)
713.329.1600 (switchboard)
alex.johnson@xxxxxxxxxxxxxxxx


-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Airhart, Chad M.
Sent: Wednesday, September 05, 2007 2:36 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Modbus Multidrop

We have two Foxboro Integrator 30's for connection to devices with
Modbus.  I now have to connect multiple devices to each Modbus
integrator so I want to do a multidrop for each.  Each integrator
connects to a P0970VB configuration selector.  The manual shows that
card going to a J478 or J878 modem then modbus bus connected to a J478
or J878 modem at each device.  The only J478 or J878 modems I found on
the internet look like 1970's vintage boxes.  How are you guys doing
multidrop (where each connected device is via RS-232) and with which
equipment (vendor/model numbers)?  Looking for standard off the shelf
equipment if possible.  Any help would be appreciated.
Chad M. Airhart
Principal Engineer - Lyondell Chemical Co.
Instrument, Electrical and Control Systems Engineering
Victoria Plant
Ph. (361)572-2568
Fx. (361)572-2541
Cell. (361)935-3230




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