Re: [foxboro] FW: Modbus Multidrop
- From: <Jack.Easley@xxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Mon, 10 Sep 2007 11:24:34 -0500
Our only multi-drop Modbus implementation with an Integrator 30 uses an
RS-232 to RS-485 converter, not a modem.
Jack Easley
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of C. M. Airhart
Sent: Wednesday, September 05, 2007 9:21 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] FW: Modbus Multidrop
FW: Modbus Multidrop
I sent this earlier but wasn't sure it made it out. The IT Nazi's have
a
pretty good grip on our email and internet access. Any help with the
Modbus
would be appreciated.
______________________________________________
From: Airhart, Chad M.
Sent: Wednesday, September 05, 2007 2:36 PM
To: foxboro@xxxxxxxxxxxxx
Subject: 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)? Does everyone
put
in 232-485 converters on the devices and I-30? Our P0970VB
configuration
selector has a 25 pin connector connected to a cable connected to a
pigtail
to 9 pin 232 connected to our current device. Has anyone used a 25 pin
232
to 485 converter directly off the P0970VB configuration selector?
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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