Checklists for Redundancy Systems

The redundant chassis are the same size, for example, both are 1756-A7, 7-slot chassis.

Use one controller in each chassis.

Modules in the redundant chassis pair meet the requirements described in Redundant Chassis Requirements.

Each chassis of the pair is composed of identical modules that are of identical redundancy firmware revisions and catalog numbers.

Partner modules are placed in the same slots of both chassis of the redundant pair.

I/O modules are not placed in the redundant chassis.

I/O is not placed in redundant chassis.

I/O is connected to the redundant chassis by the same network as the redundant controller chassis without bridging.

For non-safety redundancy applications, if you do not use concurrent communication with I/O, all I/O and consumed tag connections in the I/O tree of the redundancy controller must be multicast connections. The I/O tree of the redundancy controller can contain produced unicast tags that remote devices consume.

Produced and consumed safety tags are not configured in Logix SIS applications.

One redundancy module is placed in the same slot of each redundant chassis.

Redundancy modules meet the requirements that are described in Redundancy Module Requirements.

A fiber-optic cable connects the redundancy modules in the redundant chassis pair. The following are catalog numbers of fiber-optic cables you can order from Rockwell Automation:

You can make your own fiber-optic cable that is up to 70 km (229,659 ft) for 1756-RM3 modules, depending on the SFP used. For more information, see the Redundancy Module Installation Instructions, publication 1756-IN095.

Identical ControlLogix® controllers are placed in the same slot of both chassis of the redundant pair.

Partnered controllers are identical in firmware revision.

Controllers meet the requirements that are described in Redundant Controller Requirements.

Identical

EtherNet/IP™

communication modules are placed in the same slot of both chassis of the redundant chassis pair.

EtherNet/IP™

communication modules meet the requirements that are described in Communication Module Requirements.

Produced and consumed tags meet the requirements that are described in Produced and Consumed Tags.

Produced and consumed safety tags are not supported in Logix SIS.

USB ports of communication modules in the redundant chassis are not used while the system is running (online).

IP addresses of devices on the

EtherNet/IP™

network are static and IP address swapping is enabled. Other IP address configurations are permitted, but require additional considerations. See IP Address Swapping.

The partner

EtherNet/IP™

communication modules must be able to communicate to each other over the Ethernet network.

Data server communication recovery time is the time during a switchover from primary to secondary, when tag data from the controller is unavailable for reading or writing. See Reduce Data Server Recovery Time.

HMI meets the requirements that are described in HMI.

The redundancy module date and time are synchronized via

CIP Sync™

or have been set by using the RMCT. This is not required, but recommended.

If using

CIP Sync™

, select Time Sync and Motion on the Module Definition dialog box for the communication module in the local chassis.

One project is created by using programming software and is downloaded to the primary controller.

Enable redundancy on the Redundancy tab of the Controller Properties dialog box. This is the only setting on the Controller Properties dialog box that is required for redundancy to function. The configurable settings on other tabs of the Controller Properties dialog box are optional, and not required for redundancy to function.

Time synchronization is not required for redundancy to function. If your application requires time synchronization, then do the following:

Task configuration is either:

The redundant controller program does not contain these tasks:

Programming for critical I/O that must be bumpless is placed in the highest-priority user task according to your task configuration.

If you use this task structure	Then programming for bumpless I/O is in
Multiple periodic tasks	The highest-priority periodic task where only that one task is at the highest priority.
One continuous task and one or more periodic tasks	The highest-priority periodic task where only that one task is at the highest priority.
One continuous task	The continuous task.

Scan time is minimized by using these techniques when possible:

For produced and consumed data, the communication module in the remote chassis that holds the consuming controller uses the Comm Format: None.

Critical messages from a remote chassis to a redundant chassis use cached connections.

Active tags on scan per controller are less than 10,000 tags/second.

Measure potential alarm bursts during system commissioning and modify the commissioned project if measured scan times are not acceptable.