DeltaV SIS Expands Scope, Boosts Speed

Oct. 1, 2009
Sometimes Bigger Really Is Better

Giving one application or process the ability to shut down safely is good. Extending and coordinating safety instrumented system (SIS) capabilities to an entire plant or other large facility is better. And making this facility-wide SIS more secure at the same time is even better.

"We've changed DeltaV SIS's ability to integrate its logic across logic solvers, so it doesn't just handle logic solvers located on the same backplane, but can expand its communications across a whole facility. This means users can employ DeltaV SIS to incorporate their fire and gas logic, emergency shutdown and other functions across their entire site," says Mike Boudreaux, Emerson's DeltaV SIS product manager. "And we've given users the ability to create a protected DeltaV SIS template in a master system, so they can distribute their SIS anywhere they want it, but still protect it."

This is the essence of two major enhancements that Emerson Process Management made to its DeltaV SIS safety management system, which were unveiled this week at its Emerson Global Users Exchange in Orlando, Fla. These new features were made available for sale September 28, and will be delivered in mid-2010.

"DeltaV SIS now can communicate across an entire facility." Emerson's Mike Boudreaux explained the new ability to integrate logic across geographically distributed logic solvers, rather than just those on the same backplane.The main architectural change in how DeltaV SIS can be used and distributed is called SISNet Domains. Aided by advances contained in the DeltaV's new Version 11 software, SISNet Domains increases DeltaV SIS's communications ability by 15 times by changing and expanding the number of logic solvers with which DeltaV SIS is able to communicate from one to 15. This is accomplished by using redundant CPUs with integrated I/O points to read input signals, process logic, and then write to output channels, explains Boudreaux. "Each logic solver in DeltaV SIS now has 16 I/O channels, and these channels can be configured to the different I/O points that need to be wired up to it," he said.

DeltaV SIS was released in 2004, and it has consisted of a distributed modular architecture with distributed logic solving since that time. This architecture was used to fit the IEC 61511 standard's model that calls for Safety Instrumented Functions (SIFs). "However, there were some limits on communication between logic solvers in the 2004 release, and this was an itch that we really wanted to scratch for a long time," said Boudreaux. "So, in DeltaV Version 10, we doubled the communication bandwidth between logic solvers from Version 9, and now, with help from Version 11, we've increased these communication abilities another 15 times."

The main beneficiaries of the much-improved communications that SISNet Domains brings to DeltaV SIS are expected to be large oil and gas refineries, petrochemical plants and other geographically large facilities with correspondingly huge process control systems. These sites usually have separate operations units going to different safety areas. "They can now fit their SIS to their overall process, and put safety where and how they want it," said Boudreaux. "If they need a global shutdown in response to a fire and alarm or an e-stop, then SISNet Domains and DeltaV SIS makes it much easier for them to do it."

Likewise, while Version 10 could wire more than 16,000 I/O points and hook 32 safety nodes together, Version 11 allows up to 30,000 I/O points and can connect up to 100 safety nodes together. "This means there is no practical limit to the size of the system that DeltaV SIS can be applied to protect. We can scale it to applications of virtually any size," added Boudreaux. "SISNet Domains gives us the confidence that DeltaV SIS can meet the scalability requirements of even the largest projects."

In addition to SISNet Domains, the second big improvement to DeltaV SIS is its Protected SIS Composite. This new feature allows DeltaV SIS users to create software templates in a master system that can be distributed—but still protected—anywhere that users need them to go. "These templates have no password, and so they can't become unprotected, and they can't be altered because they are custom function blocks," explained Boudreaux. "As a result, if a safety engineer or other user wants to create an internal safety standard, then they can create their own function blocks and write their own standard around them. They all employ logic in the same way."

In addition, DeltaV SIS also supports the HART Version 7 protocol, which will help users prevent unauthorized calibration or other changes to instruments in the field. "These kinds of changes might come from technicians using handheld devices in the field, and so this feature will help them use handhelds more safely," added Boudreaux.

Finally, DeltaV SIS will now have a faster I/O update speed, which is the time it takes for I/O data from the SIS to be read by the DeltaV controller on the control side. Previously, Delta V SIS had one update per second, but now it will allow one update per 100 milliseconds. "Some applications may need quicker updates from their I/O points to a control module in their process control system," added Boudreaux.