Spurred by advancing technology and changes in industry standards, single-system platforms for safety and standard control have become more cost-effective than ever to design, implement and maintain, according to Rockwell Automation.
Economic factors are driving the evolution of safety systems from older hardwired to networked to contemporary integrated configurations. The more designers can integrate the innovative safety functions of a control system with non-safety functions, the better the opportunity to minimise equipment redundancies and costs while improving productivity. Hardware costs can be decreased because standard and safety portions of the application can share system components.
Integrated safety systems use a single programming software package which can eliminate the need to write and coordinate multiple programs on different controllers. This in turn can simplify application programming and help reduce training and support costs.
Furthermore, a single development environment helps eliminate expensive redevelopment. For example, if a control engineer needs to scale from one line to three, it’s as simple as porting the necessary application from one to the next. Fewer components also mean smaller panel enclosures, saving money on control cabinets and floor space.
CIP safety
Another important step is the introduction of CIP Safety. The Common Industrial Protocol (CIP) is independent of the physical network, providing a set of common services for control, configuration, collection and sharing across all of the CIP networks, DeviceNet, ControlNet and EtherNet/IP.
In the past, a safety event in one zone could result in the entire machine shutting down because the standard system had limited knowledge of it. CIP Safety allows the control and safety systems to coexist on the same network and share data between the safety and standard applications. This enables engineers, for example, to perform ‘zone control’ where one zone of the machine is brought to a safe state while others continue to operate.
Unlike conventional systems, the integration of the safety and standard control systems provides operators and maintenance personnel with visibility to all machine events – including safety – via the machine or system HMI. With the knowledge and insight provided by the integrated system, plant personnel can respond quickly to return the machine to full production. CIP Safety also helps eliminate the need to install expensive and difficult-to-maintain gateways between each network.
Before the development of safety networks, engineers often had to use smaller systems or minimise their performance requirements since it was difficult to hard-wire interlocks and relay-based safety logic into a complete automation system. Now, engineers can integrate their devices on common physical network segments and allow safety and standard information to flow between devices and controllers.
Next generation safety control
Recent developments in integrated safety involve leveraging the benefits of a common control platform and extending them into a more compact, scalable form factor. This gives users more design flexibility, allowing them to apply integrated safety functionality across a broader range of applications, including many in the midrange where a larger controller previously would have been excessive or cost-prohibitive.
The new Allen-Bradley Compact GuardLogix programmable automation controller (PAC) from Rockwell Automation performs all machine control functions – including drive, motion and high-speed sequential control – while simultaneously executing SIL 2 and SIL 3 safety functions. Suitable for midrange applications, this multi-discipline controller offers designers safety functionality previously found only in larger integrated systems.
Integrated safety offers the advantages of a common programming environment which helps reduce design, configuration, startup, and maintenance time and costs. With a single software program managing both safety and standard functionality, engineers no longer need to manually manage the separation of standard and safety memory or worry about partitioning logic to isolate safety.
Improved consistency
New software tools such as high-integrity add-on instructions (AOIs) are contributing to even more accurate and efficient safety system designs. AOIs encapsulate code for common routines into pre-validated modules that can be easily reused. This promotes consistency between projects, helps simplify debugging and troubleshooting and minimises the risk of coding errors.
These high-integrity AOIs employ a signature feature to help designers protect their data from being accidentally or intentionally altered. This revision control capability is critical in highly regulated industries where manufacturers need to maintain consistency to meet regulatory requirements and protect intellectual property.
As safety and standard components continue to become more seamlessly integrated into control system designs, implementing safety will no longer be a separate discipline but rather a concurrent and more natural part of the design process.
In turn, these innovations will help keep personnel and machines safer while boosting the bottom line.
