Data-enabling safety relays add value to simple machines

Inside Machines: Safety relay advances help machine builders cost-effectively meet customers’ compliance goals while addressing needs for a connected enterprise.


Machine builders asked to meet customers' requirements for safety compliancy and provide access to production information in one safety component have had very few cost-effective options; depending on the application, an advanced safety relay may meet those needs. Sophisticated integrated-safety controllers can manage safety functions and seamlessly share information enterprise-wide, but they are cost-prohibitive for simple safety functions. Cost-effective safety relays and simple controls manage safety functions but do not share production and diagnostic information.

Rockwell Automation safety solutions include the Allen-Bradley Guardmaster 440C-CR30 configurable safety relay (shown). These relays are configured via the Connected Components Workbench software from Rockwell Automation and can be used in conjunction wit

In the past, safety relays had to be hardwired back to the controller for any diagnostic information. Multiple safety functions were addressed by adding multiple safety relays, taking up additional panel space and complicating troubleshooting.

Safety diagnostics are not just for safety. Information end users can gain from recent advances in safety relays that can help protect those on the plant floor and also help keep production levels high, ease troubleshooting, and reduce downtime.

With the growth of—and priorities around—networked connectivity, the automation industry has responded to machine builders' needs. Machine builders of simple machines now can gain diagnostics and network safety functions without implementing overly sophisticated safety systems. They can keep safety functions and standard control separate, but use one network to share data for one system view. 

More options for implementing safety

Two options now available to machine builders and end users are safety relays on a network and configurable safety relays. Machine builders can choose the safety solution and standard control for any level of complexity that meets the required safety functions and budget.

The first option is putting a safety relay on an ODVA EtherNet/IP network, connected to the controller. For the lowest level of complexity, networking safety relays allows machine builders to stay at fewer I/O points by providing more production-data insights by using an Ethernet protocol.

Machine builders who want to stick with standard control and simple safety can also gain diagnostics with configurable safety relays. These relays only require a network connection to the controller, easing setup and troubleshooting. With one communications interface for standard control and safety, users can see extensive diagnostics and status information.

Some configurable safety relays can now be programmed in the same software environment as the standard control, reducing costs for initial wiring of safety and safety diagnostics. The flexible configuration also allows end users to re-engineer and more rapidly integrate application changes without incurring the high cost of rewiring. 

Faster restarts, application example

Networking simple safety functions-through either a safety relay or a configurable safety relay-provides machine-production insights to end users, eases wiring and troubleshooting, and improves uptime and productivity. It keeps safety simple, separate, and flexible.

For example, consider a food manufacturer that has a bread-slicing and bagging production line. The bread slicer is contained within an enclosed area, with an e-stop and guarding functions. Once the bread is sliced, it moves down the line to a separate machine for bagging. If the door to the slicer opens, the e-stop is triggered and the line shuts down.

Until recently, the facility operator would have to manually check all parts of the line to confirm what had happened, extending downtime costs.

Now, machine builders can provide bread-slicing machines with networked safety functions. Diagnostics are communicated to a human-machine interface (HMI) for easier viewing. The operator can see that the door is open, shut it, and more quickly and safely restart the line.

Safety scales, information flows

The same benefits can be gained across industries, from consumer packaging goods to automotive-in any machine with a simple safety system. Machine builders also can retrofit machines with configurable safety relays for end users, removing numerous safety relays from the panel and adding insights.

Leading automation providers know that safety scales, but information always flows. Builders of simple machines now have options for diagnostics at any level of complexity and control.

For example, a configurable safety relay can communicate via Ethernet with an EtherNet/IP network interface designed for safety applications. The safety relay, configured with software from the same vendor, can serve as the standard control.

- Thomas Helpenstein is product manager, Rockwell Automation; edited by Mark T. Hoske, content manager, CFE Media, Control Engineering,

ONLINE October has additional information and links.

Key concepts

  • Advanced safety relays help machine builders cost-effectively meet customers' compliance goals while improving networked communications in the enterprise.
  • Machine builders can retrofit machines with configurable safety relays for end users, removing numerous safety relays from the panel and adding insights.
  • Simple safety functions, when networked, provide machine-production insights to end users, ease wiring and troubleshooting, and improve uptime and productivity.

Consider this

Have you re-examined the efficiency of your machine safety designs in light of updated machine safety technologies? 

ONLINE extra

See a related safety product below. Also see the Machine Safety page from Control Engineering and the Machine Safety Blog. 

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