[foxboro] OPC in General (was: AIM OPC Server)
- From: "Johnson, Alex (Foxboro)" <ajohnson@xxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Mon, 7 Mar 2005 16:46:29 -0500
Re: OPC Future
Looks like OPC is moving to their Unified Architecture (OPC-UA) which is web
service based.
The impact is basically that we are back to the future (ASCII text files -
aka XML - moving using file transfer - aka HTTP/SOAP). :)
Gist of this is OPC is moving to less efficient, but more independent
delivery of data.
It's great for certain classes of problems, e.g., asset management of device
configuration data, but not so hot at others - HMI support. That is, as the
object becomes more complex and needs to update less often OPC UA shines.
I doubt that it will be used where OPC DA is today. Our small process
control objects (value, status, time tag) are pretty inefficient if you have
to convert them to and from ASCII to move them.
Re: OPC DA
I'm not a big fan of OPC DA becoming the lingua franca of our business which
it is. DCOM has no business in field equipment.
But OPC has a big advantage - status bits in a standard format and time tags
and lots of folks want them.
So, if one it going to do it (and vendors must) our FDSI FBM is the right
platform (lesser evil?) since it isolates the other system from the control
network which is full of Windows boxes.
I suspect that isolation will be very valuable over the next few years.
Re: EthernetIP or Alex displays his ignorance
I'm no expert. Does it offer status bits and time tags for its values?
Regards,
Alex Johnson
Invensys Process Systems
Invensys Systems, Inc.
10707 Haddington
Houston, TX 77043
713.722.2859 (voice)
713.722.2700 (switchboard)
713.932.0222 (fax)
ajohnson@xxxxxxxxxxx
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Corey R Clingo
Sent: Monday, March 07, 2005 2:55 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] AIM OPC Server
This kind of thing is why I really would like a more open, OS- and
application-independent, closer-to-the-wire protocol (say, something more
akin to Ethernet/IP, to provide one example) to supercede OPC. I'm no OPC
expert (I dabble in it just enough to get it working), but I fail to
understand why one needs a DCOM and RPC infrastructure just to get data
from a control system when a simple TCP socket will do. And anyone who
has ever tried to make Windows boxen work through firewalls knows how
a-cough-crappy-cough-dept Microsoft is at designing network protocols
(LANMAN, Netmeeting...).
Not to mention the issue of being at Micro$oft's mercy. I read recently
some comments from a member of the OPC Foundation. He saif that .NET is
not really fast enough to do real-time data access, based on some
experiments they've done (OPC-XML I think they call it), and is hoping
that gigabit Ethernet and "faster processors" (what? 8-way? Multi-core?
"Cell"?) mitigate the problem. He also stated a desire to move OPC in a
more platform-independent direction. Hmmm....
Corey Clingo
BASF Corp.
"Ken Heywood" <kheywood@xxxxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
03/03/2005 10:13 AM
Please respond to foxboro
To: foxboro
cc:
Subject: Re: [foxboro] AIM OPC Server
I'm always game for free advice. Application tunneling always makes life =
easier. But, it's kind of perverse when you have many workstations that =
expect to use the benefits of named OPC object access sourced from all =
kinds of devices, and you need to load the client apps for all the =
devices on every workstation. It's akin to telling Internet users that =
they can display any webpage as long as they have ActiveX loaded.
Barring any DCOM issues, 3 or 4 NIC cards shouldn't present a problem =
... I think. No?
* K
-----Original Message-----
From: Johnson, Alex (Foxboro) [mailto:ajohnson@xxxxxxxxxxx]=20
Sent: Wednesday, March 02, 2005 2:02 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] AIM OPC Server
Free advice?
Put the AIM*OPC DA Server on the client machines and use NetAIM*API to
connect to the source AW (AW70 or AW51). This is equivalent to =
Matrikon's
"OPC Tunnelling".
Why do it?
Easy - the setup is much simpler - no DCOM.
Worth the time and money, I promise.
Regards,
=20
Alex Johnson
Invensys Process Systems
Invensys Systems, Inc.
10707 Haddington
Houston, TX 77043
713.722.2859 (voice)
713.722.2700 (switchboard)
713.932.0222 (fax)
ajohnson@xxxxxxxxxxx
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Ken Heywood
Sent: Wednesday, March 02, 2005 12:26 PM
To: Foxboro Freelist (E-mail)
Subject: [foxboro] AIM OPC Server
Content-Type: text/plain;
charset=3D"iso-8859-1"
Content-Transfer-Encoding: quoted-printable
=3D20
I am planning an AIM OPC Server to serve data to two separate networks. =
=3D
The box will have 3 NIC cards; 1 for I/A, and one each fro each IT =3D
network. Are there any special AIM restrictions? Network addressing or =
=3D
network connection issues? Has anybody done this? Thanks.
=3D20
* K
=3D20
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