1 Introduction
Safety systems that transmit safety signals over Ethernet networks such as POWERLINK offer several advantages over hard-wired safety circuits. These advantages include cost savings by reducing the amount of wiring required, as extensive wiring is a well-known source of error, especially in complex modular machines. Traditional safety wiring also delays system deployment because it requires prior knowledge of all options to be used. However, safety systems with direct communication capabilities bypass controller routing, allowing for higher data transmission speeds and significantly increased data throughput. Drive components with SmartSafeReaction functionality, mounted directly on the motor, reduce stopping distances, optimize safety clearances, and facilitate machine miniaturization and low-cost manufacturing.
2 From Machine to Production Line
In the printing and packaging industries, high levels of automated production are achieved through interconnected machines and robotic arms. Therefore, there is a strong interest in extending networked security technologies across the entire production line and leveraging their advantages across all relevant machines. However, organizational and technical barriers have consistently hindered the exchange of security signals between machines and robotic arms via Industrial Ethernet.
The organizational issue is that no machinery manufacturer can anticipate and plan for all potential connectivity needs of external devices, let alone foresee how to implement them. Furthermore, individual safety devices outside the machine cannot trigger a deeper safety response compared to those inside the machine.
Technical barriers arise from incompatibility between various safety-oriented control systems. Apart from openSAFETY, they can only work with control hardware and fieldbus systems from specific vendors. Therefore, even today, it remains very common to connect machines by sharing emergency stop circuits.
3. Security interfaces mean interoperability
Regardless of the system bus used for data transmission, openSAFETY is the only system capable of integrating into a network for transmitting and processing security-related data. Therefore, even if individual machines come from different manufacturers or are equipped with different security features, the same security technology can be easily adopted among these machines. Regardless of the fieldbus used, secure data transmission across multiple units can be achieved through openSAFETY, as shown in Figure 1.
Figure 1
Despite the high degree of independence of such systems, it remains unlikely that a unified security standard will be established and accepted by every machine supplier.
“For this reason, it is essential to handle interoperability between different security systems at the network layer so that their full functionality within the network can be utilized,” explains Miodrag Veselic, openSAFETY Technical Manager at B&R. “B&R and OMAC are working together to develop a specification for an interface protocol designed to allow machines using different systems to easily network security-oriented systems,” as shown in Figure 2.
Figure 2 Market Share: openSAFETY can handle 91% of industrial Ethernet applications.
4. Machine configuration files are key.
A unified profile is a core element of machine and system safety-oriented networks, describing the basic design of safety-related components on each machine or manipulator. “This relates to a well-defined set of status signals throughout the system and equipment, including emergency stop, installation mode, deviation from limits, etc.,” Veselic explains. “The machine profile specifies for each signal whether it is transmitted by the device or whether the device needs that signal for its own safety response.”
The configuration file features a simple data structure that allows security systems from different manufacturers to be integrated into a single network, enabling the sharing of basic security-related information. This allows each individual machine in different locations to respond to security-related operating mode settings, thereby improving device and system availability. Because openSAFETY employs a "black channel" mechanism, transmitting security signals relies solely on the network communication layer, allowing the creation of this type of network using any Ethernet topology. A key aspect of the generic security interface specification is its ability to add or remove devices without disrupting or shutting down the rest of the network.
5. What is the main purpose? Ease of implementation.
The interface protocol and the processing method for machine configuration file data have not yet been finalized. However, the specification is still expected to be completed sometime in 2012. "The success of the interface will ultimately depend on how easy it is to implement," Veselic explained. "Therefore, the configuration dataset must be converted into software to make integration with security system vendors as easy as possible. For simple devices or equipment without built-in security controls, B&R will provide adapters with this functionality, and other manufacturers are likely to offer similar products as well."
Once the standard interface profile structure based on secure Ethernet data transmission is released, machine manufacturers only need to complete the one-time development of the machine profile to ensure compatibility. Furthermore, they can focus their attention on the safety features within individual machines and do not need to constantly consider evolving customizations, including robotic arms. Because development and certification are one-time processes, this shortens the time-to-market period.
6. Network-based security systems improve productivity
Another advantage for customers is the high availability of machines, robots, and robotic arms, which can be used as modular building blocks to easily create complex production systems in advanced, universal safety environments. These systems offer a wealth of easily manageable tasks, and their configurations can be modified at any time to increase productivity—something previously impossible with traditional technologies.
SmartSafeReaction, such as the "Safe Reduction" (SRS) function, can be enabled simultaneously on multiple machines, providing a safe state without completely halting the system—a way to improve productivity. Employing a comprehensive safety mechanism across the entire production line to protect the entire system can also increase productivity. This not only shortens the route and time for safety data transmission but also saves space because safety responses on adjacent machines no longer require separate maintenance channels.
“Another advantage of network-layer-based secure systems is that it can perform high-quality and consistent diagnostics across all machines,” said Franz Kaufleitner, Product Manager of Integrated Security Technologies at B&R. openSAFETY is a unified security solution for all industries, as shown in Figure 3.
Figure 3
“Another advantage of network-layer-based secure systems is that it can perform high-quality and uniform diagnostics across all machines,” said Franz Kaufleitner, Product Manager of Integrated Security Technologies at B&R.
