Insights in Controls and Automation

A step forward with Allen-Bradley High Availability Redundant I/O

  

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This posting’s Content: 

1. The Automation Fair
2. Redunant I/O

 Next posting’s content:

1. Two Ethernet ports, Ethernet Rings and Allen-Bradley

The Rockwell Automation Fair is one of the best places to see what the automation industry is “thinking”. 

My goal in attending Automation Fair 2010 was to provide our clients an unbiased opinion of new hardware, software, and services available to the manufacturing industry.  Our customers have found it very refreshing to hear from someone without an Allen-Bradley point of view which is what I will be doing here.

Each blog posting will highlight one specific area that I hope you find enlightening.  Please check the blog routinely to see added postings.

Redundancy.  There are two new items that Allen-Bradley is featuring related to control systems redundancy:

• Redundant I/O:
• Ethernet rings:

 Allen-Bradley has a good proven architecture for redundant PLCs with their ControlLogix platform.  More discussion on this in a future posting.

Whenever you consider the need for redundancy, there are always multiple points of possible failure that could be catastrophic to the system.  In this case, Rockwell is addressing two more of these points:

Redundant I/O, named “High Availablility”:  Picture an Ethernet cable (communicating via Ethernet IP) coming from a ControlLogix CPU to this new I/O cluster.  Lets assume you would normally have a 16-point discrete input module.  In this case you would have two input modules that act redundantly.

During normal operations, the first discrete module is functioning.  If it fails, the second module picks up functioning in a seamless manner.

The same functioning occurs for all conventional type I/O modules;

• Discrete output
• Analog input
• Analog output

You also have the flexibility to mix and match in the same cluster.  For example, you could have redundant discrete input modules, while at the same time have a non-redundant analog input module.

If you want our opinion if this would be cost effective in your application, contact me at salter@primarysys.com