ControlLogix Redundancy System

[gluca]

I'm developing a project for a ControlLogix Redundancy System, using 2 chassis with the 1757-SRM modules.

The redundant processors control some ControlNet remote I/O via a CNB module, and I would need to control several DeviceNet Soft Starters too.

The Redundancy System User Manual says you cannot install a DNB in the redundant chassis, and advises to use a Gateway (a chassis with a CNB and a DNB), in order to connect to the DeviceNet via the ControlNet (supportedby the SRM).

My questions are:

1) Is it possible to connect my ControlNet to the DeviceNet (in order to bumplessly control my Soft Starters) with a 1788-CN2DN Linking Device instead of using a Gateway? I would prefer this solution due to lower cost and dimensions.

2) Is it possible to develop a complete redundant solution using 2 gateways or Linking Devices, in order to bumplessly control my application in case of a Gateway failure?

Thank you,

Gianluca Caredda

 

[Bitmore]

gluca,
yes, your preferences are best....

http://domino.automation.rockwell.c...146467486DF1BE4A85256B8F00748EE6?OpenDocument


Hope that answers your question.

Bitmore

 

[Contr_Conn]

I think you can do redundant DeviceNet using dual Flexlogix PLCs with special firmware.
Look in the knowledge base.

 

[Ken Roach]

The 1788-CN2DN works fine with redundant ControlLogix CPU's on ControlNet.

As you suspect, though, you cannot put two 1788-CN2DN's onto a single DeviceNet and get master redundancy on the network.

The discussion can degenerate into an argument at this point; after all, what's the use of having redundant network masters if the network media, network slaves, and connected motors are all single points of failure.

It's an intriguing idea to use two FlexLogix running their "DeviceNet Warm Backup" feature. They would be about the same size as a CN2DN but a more expensive option.