Advancing technology and changes in industry standards have resulted in single-system platforms for safety and standard control becoming easier and more cost-effective to design, implement and maintain. Economic factors are driving the evolution of safety systems from older ‘hard-wired’ to networked integrated configurations. The more designers can integrate the safety with the non-safety functions of a control system, the better the opportunity to minimise equipment redundancies, improve productivity and minimise costs.
Along with eliminating the need for a separate safety controller, integrated safety systems also use single programming software. This means no need to write and coordinate multiple programs on different controllers, thus simplifying application programming and reducing training and support costs.
CIP Safety allows integration
Another important step in the evolution of integrated safety occurred with the introduction of common industrial protocol (CIP) Safety. Seamless communication in the past was near impossible because no single network was able to integrate safety and standard control systems, while enabling the seamless transport of data across multiple plant-floor physical networks. That changed with the CIP, an application protocol for industrial networking that is independent of the physical network. CIP provides a set of common services for control, configuration, collection and sharing across all the CIP networks, DeviceNet, ControlNet and EtherNet/IP.
CIP Safety allows the control and safety systems to coexist on the same network and to 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.
CIP Safety also helps eliminate the need to install expensive and often difficult to maintain gateways between networks. 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 mid-range applications where a larger controller previously would have been excessive or cost-prohibitive.
The Allen-Bradley Compact GuardLogix programmable automation controller (PAC) provides the ultimate in integration by performing all machine control functions – including drive, motion and high-speed sequential control – while simultaneously executing SIL 2 and SIL 3 safety functions. Compact GuardLogix is ideal for mid-range applications where it offers safety functionality previously found only in larger integrated systems.
Integrated safety also offers the advantages of a common programming environment, which helps reduce design, configuration, start-up and maintenance costs. With a single software program managing both safety and standard functionality, engineers no longer need to manage the separation of standard and safety memory or worry about partitioning logic to isolate safety.
Improved control, 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 that is capable of being pre-validated and easily reused. This promotes consistency between projects, helps simplify debugging and troubleshooting, and minimises the risk of coding errors.
The future of integrated safety points to more options and more flexibility to apply safety technology to meet specific needs. As safety and standard components continue to become integrated more seamlessly into control system designs, implementing safety will no longer be a separate discipline, but rather a concurrent and natural part of the design process. In turn, these innovations will help keep personnel and machines safer while boosting the bottom line.
For more information contact Adrian van Wyk, Rockwell Automation, +27 (0)11 654 9700, [email protected], www.rockwellautomation.co.za
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