John,
Thank you for taking the time to provide the information concerning Allen
Bradley PLCs. I thought it was very informative.
As of last week, my group will start to take on our facility's AB PLC
responsibilities in addition to our current Foxboro I/A support. I know little
about the Allen Bradley product so I have a steep learning curve ahead of me.
My goals are to some how network the PLCs together for information transfer and
remote support purposes, and to implement some software that makes the PLC
programming much easier (than the relay logic look) to implement and documents
the logic for non-experts to easily follow. I would appreciate any tips that
you and others can provide to me.
I do not even know what Allen Bradley product we have yet, but I think some of
them are SLC150, SLC5/04, PLC5/11, PLC5/20, and a Panel View (??) station. The
PLCs are scattered around the facility on process equipment that is controlled
various independent Foxboro systems and few, if any of them, are currently
networked together. We will want some of the Foxboro systems to somehow get
information from PLCs that are installed in their area, but we also want to be
able to access all of the PLCs from common designated locations (say designated
Office PCs with the correct security). One of the reasons to link the PLCs to
the Foxboro systems will be to provide PLC trip alarms, historization of the
contact states in PI, and a better means for the process operators and engineers
to somehow view the states of the PLC logic.
>From reading the AB emails, it sounds like some of our future directions should
be:
1. Work towards installing AB PLCs with an ethernet interface.
2. Use the Foxboro Micro I/A or an AW to provide desired interfaces to Foxboro
systems. We do not need PLC redundancy.
Some of my questions are:
1. What is the best way to provide process operators and engineers a view of
what is happening in the PLC in an easy to understand manner with minimal
upkeep.
2. We would like to implement some software that makes Allen Bradley PLC
programming as easy as possible and also that provides logic documentation that
is very easy for non relay logic experts to follow. Any suggestions?
3. The purpose of most of our PLCs is for external shutdowns (SIS). Will
Control Logix provide any real benefit? Is Control Logix considered to be
robust enough for SIS, or should it be used in conjunction with the PLCs?
4. If we network our PLCs together in some manner, will it keep us from also
using Micro I/A or an AW to somehow interface designated PLCs to designated
Foxboro systems?
5. Besides the purchase of the AW, what all do we need to purchase to use an AW
for the interface? Does it matter whether we use a Unix or NT AW?
Regards,
Neil Martin
Huntsman Petrochemical
____________________Reply Separator____________________
Subject: RE: Integrator 30's vs. AB Stations
Author: John Metsker <[EMAIL PROTECTED]>
Date: 05/08/2000 1:05 PM
Sorry for being late to the mix and continuing to drag out this issue. This
discussion should be linked to the e-mail flurry about AB Control Logix and
Ethernet connectivity from a month or so ago. (I would assume that your AB
connectivity strategies need to include support for the new AB product
directions.)
At General Mills, we are using AW51 Integrators to provide AB gateway
functionality. Yes, the Foxboro software bundling says that it is an AW and
it can act as an all in one machine, but they are being deployed as
"dedicated" Integrators. (Basic premise of distributed control; keep
"control" separate from everything else. We may be a food company, but
we're not stupid.)
How come? Seems like overkill doesn't it.
AB Interchange from Rockwell Software and Ethernet connectivity. (The AW 70
Integrator cousin uses RSLinx.)
Why would anybody want AB connectivity that doesn't utilize the standard
communication libraries that are developed and tested by Rockwell software?
Every other major software vendor (Wonderware, Intelluion, MDT, SAP, etc..)
that communicates with AB equipment develops applications that utilize
RSLinx or Interchange. Why should Foxboro be different? Foxboro is no
great lover of PLCs and Allen Bradley/Rockwell in particular. Their
products should have a headstart and take advantage of the connectivity that
is provided by Rockwell themselves.
Why not any of the other AB connectivity products from Foxboro?
ABGW or the ABGW30? The serial interfaces are too much of a bottle neck.
The food industry is largely a discrete industry, we need to communicate a
lot of data at Ethernet bandwidth to/from the PLCs. The ABGW and ABGW30
hardly allows a lot of PLC words to be communicated at high speed. (Don't
have redundant PLCs, don't need a redundant PLC interface.)
AB Station? The 1 to 1 coupling of AB stations to PLCs tends to promote use
of "data concentrators" that add complexity to PLC troubleshooting. The
sideport on the PLC provides about 1/2 the throughput that the integrated
Ethernet port on PLC5E. (Ask to your knowledgeable AB rep to compare
Ethernet performance on an integrated PLC5E to an Ethernet sidecar.) The AB
coprocessor is has a Motorola 68030 chip in it. That is it for that product
from AB. They assume everybody utilizing host computers with RSLinx or
Interchange to accomplish the jobs once handled by the co-pro module.
How 'bout Micro I/A with AB Ethernet? The product is now going to be a
'late release' item with V6.2.1. Foxboro developed this product by
licensing source code from Rockwell and porting the low-level parts of it to
the VRTX O.S. that runs in Micro I/A. It is now a Foxboro proprietary
product. Also, be aware that Control Logix uses a different network
protocol stack than PLC5s. Foxboro's VRTX port of Interchange was prior to
a version that supported Control Logix. Foxboro is going to have to
completely start over with this product in order to work with CL. (The
forthcoming Micro I/A AB Ethernet interface for PLC5/SLC500 has now been in
the works for over 3 years.)
AW51 Integrator? It is able to support Control Logix with the
installation/configuration of the proper, underlying version of Interchange
(V6.2) It provides a 1 to many Ethernet interface to PLCs. Sure it has
draw backs, like a hard drive and not being redundant. The Ethernet
connectivity hopefully allows the box to sit in as decent an environment as
possible and as the prevailing chat on the email list would indicate, it is
not the stability of the hardware, but the stability of the software that is
afflicting the Foxboro User community. Redundant hardware can't help there,
but deploying the machine as simply an "Integrator 51" and reducing the
functionality of it improves it's stability greatly.
Oh yea, the price. Well, let me be the first one to tell you that the price
of cereal will be going up. Foxboro marketing needs to be involved. A full
AW station license should not be charged if a 51 series machine if is going
to be utilized as an "Integrator 51". A Gateway software bundle for the 51
was in the works as part of V6.2, but that was dropped like so many other
things have been. The hardware part of it will forever perplex me. Why can
Foxboro develop/manufacture there own proprietary DIN rail computer and sell
it at a somewhat desirable price, but they have to sell a Sun box at double
or more of the street price.
Anyway sorry for being long winded. I hope this provides some different
perspective on Foxboro/AB integration strategies. Your feedback is
appreciated.
Thanks,
John Metsker
General Mills, Inc
-----Original Message-----
From: Johnson,Alex [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 04, 2000 10:17 AM
To: Foxboro DCS Mail List
Subject: RE: Integrator 30's vs. AB Stations
Re: PSS
Check with your account rep or, you can get if from www.csc.foxboro.com
<http://www.csc.foxboro.com> . I just checked and if you search for "PSS
21H-6C6 B4" on the CSC page it will take you to a list and this document was
the second one on the list.
Re: Redundancy
The Micro I/A solution is not redundant that I am aware of, but you can
always go point to point just like with the DI30 and have only one PLC per
Micro I/A.
Regards,
Alex Johnson
The Foxboro Company
10707 Haddington
Houston, TX 77043
713.722.2859 (v)
713.722.2700 (sb)
713.932.0222 (f)
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
-----Original Message-----
From: Stan Brown [SMTP:[EMAIL PROTECTED]]
Sent: Thursday, May 04, 2000 8:40 AM
To: [EMAIL PROTECTED]
Subject: Re: Integrator 30's vs. AB Stations
On Wed May 3 17:20:05 2000 Johnson,Alex wrote...
>
>To learn about Micro I/A check out the following PSSs or contact
your
>Account Rep. I really think that Micro I/A is a good way to go for
>integrating the devices that it supports.
>
>PSS 21H-6C6 B4: Micro-I/A Allen-Bradley PLC5/E Remote I/O
Interface
>
Alex, I am having a hard time finding this PSS. Have you got
a link, or
something for it?
And a question, if we were to go with the Micro-IA PLC ->
Ethernet
solution what redunandcny could we incorporate?
--
Stan Brown [EMAIL PROTECTED]
843-745-3154
Charleston SC.
--
Windows 98: n.
useless extension to a minor patch release for 32-bit
extensions and
a graphical shell for a 16-bit patch to an 8-bit operating
system
originally coded for a 4-bit microprocessor, written by a
2-bit
company that can't stand for 1 bit of competition.
-
(c) 2000 Stan Brown. Redistribution via the Microsoft Network is
prohibited.
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