We have Offered our GE Fanuc System to one of our Client, Basically having 5 PLC to be connected together on Ethernet and Monitored and Control from One HMI Station,

But The Toplogy They have Suggested is Ring toplogy With Redudant Ethernet Control Card,

We have Doubt after going to Web Site Whether this Ehernet will support this Ring Toplogy using Ethernet Connection, If so what are Extra Components to be Considered Like Special Hub or any other Software for

Your Quick Response will be appreciated .....URGENT

 

The Hirschmann (http://www.hirschmann.com) line of industrial switches are built with this topoligy in mind. You build a complete loop and one of the switches acts as a virtual open. On loss of one segment it auto switches to a straight through switch sitting in the middle of a open trunk line. It will feed to both ends of the line and when you repair the loop it will go back to being the virtual open in the line.

Kinda cool. We like them since we don't have to worry about a break taking us down.

Lance Jones
Automation Programmer
Sara Lee Coffee and Tea
Suffolk, VA

 

Any Ethernet device can support ring topology. The ring topology is transparent to the device so it cannot tell the difference. The device has a single TCP/IP stack and IP address. The Ethernet is split into a clockwise and counter-clockwise path in small splitter-T connections or in multiport switched or shared hubs. The network hardware manages the 'redundancy' in a similar way to the spanning tree algorithm, but much faster. This ensures
that messages are not endlessly circulating in the ring, yet a broken ring recovers within milliseconds.

Note that ring topology is not complete redundancy. If you use one ring your device still only has a single Ethernet port, and for a short distance there is just one wire, and the failure of the hub/switch will affect all
connected devices. I.e. with ring topology there is still some single points of failure.

For full fault tolerance you need two independent networks (these independent networks can be either star or ring topology) with separate hubs/switches and where devices have redundant ports with redundant TCP/IP
stacks and address. The application protocol used in the system must support such redundancy mechanism that detects faulty paths and route messages another way. FoundationT Fieldbus HSE is the only open industrial Ethernet solution that supports this kind of "DCS style" redundancy.

Indeed combining dual LAN and ring topology is a very good solution. Take a look at this article:
http://ethernet.industrial-networking.com/articles/i04_oilplatform.asp

To learn more about industrial Ethernet and redundancy, see chapter 3 and 10 of the book "Fieldbuses for Process Control: Engineering, Operation, and Maintenance" (buy online in hardcopy or download immediately in softcopy):
http://www.isa.org/fieldbuses

If you can't buy the book now, you can download chapter 1 (overview) for free in softcopy form. It's free, but you must register an account. If your email does not support this hyperlink feature correctly, please copy the entire link and paste it into your Internet browser. Mind the line wrap, make sure to get the complete path all the way to the 4585:
http://www.isa.org/Template.cfm?Section=Shop_ISA&template=/Ecommerce/Product
Display.cfm&ProductID=4585

Jonas Berge
SMAR
===========
[email protected]
www.smar.com
Learn fieldbus at your own pace: www.isa.org/fieldbuses

 

pravin,

Ethernet is not meant for ring topology. You might be able to suggest a
better solution to the customer, if you know why the customer wants a ring
topology?. What are they trying to achieve?. Do they want network fault
detection and want an alternate path to the device?. or they have some other
such requirement?.

Sincerely,

--------------------------------------
Prasanth Gopalakrishnan
Kalki Communication Technologies Private Limited
Phone: 91-80-25721263/4
Mobile: 91-98454 50872
Fax: 91-80-2572 5473
E-mail: [email protected]
Web: http://www.kalkitech.com

 

You will need special switches. Try Hirschmann or Moxa.

-James Ingraham
Sage Automation, Inc.

 

Pravin, Does the customer happen to be a Utility (electrical generation / distribution) company ? They use Ring topology for Medium voltage distribution, so they think it's the way to go with Ethernet. Now seriously, you can have it with Hirschmann Fiber Optic switches (also sold under private label by Schneider Electric) - they "self heal" a broken ring quite fast. Look for HIPER ring here http://portal.hirschmann.com/ Meir