Safety technology will allow changes with no reprogramming
The Austrian company B&R Automation is working on a technology that, it says, will provide seamless safety for production lines. It will allow machines or individual components to be added or removed from a machine network without having to reprogram the safety application.
While flexible, modular production lines are already being implemented at the functional control level, achieving comparable flexibility for safety has so far seemed to be “an insurmountable hurdle”, says B&R. But, by combining OPC UA with the openSafety open-source safety protocol, B&R believes it can change this.
“In theory, it is certainly possible to join machines from different vendors in a single safety network," explains Franz Kaufleitner, the company’s product manager for integrated safety, “but doing so requires an extensive amount of factory-floor programming.” Once the line is up and running, any time you add, remove or modify equipment, you would need to reprogram and recheck the safety application. “That's just not a viable solution in real-world conditions.”
B&R’s new technology is based on self-organising safety networks using OPC UA and openSafety. When a new piece of equipment – a machine, a part, or even a robot – is added to the network, OPC UA security mechanisms establish a secure connection. An OPC UA server can obtain a complete map of the network without any code needing to be written.
Next, the safety application checks whether the new component is already known, or if it matches a previously validated configuration. If so, the machine operator does not need to do anything else.
If significant differences are identified, the user is asked to confirm, via an HMI, whether the new configuration is correct. This input is saved, so the same configuration will be recognised automatically the next time.
“This is where openSafety comes into play,” Kaufleitner explains. Each component checks the plausibility of the configuration in the same way as the checks that are performed when a machine starts up. This includes a test of whether the response and cycle times are fast enough for reliable execution of the safety functions. Once these checks have been completed, exchange of safety-relevant process data begins via openSafety and the production line can resume operation.
Each device needs to support openSafety's E-stop profile. If an E-stop button is pressed, all of the devices in the network are notified automatically and each decides independently whether to enter an E-stop state or to continue running.
B&R is developing a profile that will allow individual components of a machine or line to communicate directly with their neighbours. If one component enters a safe state, its neighbours will decide autonomously whether they need to enter a safe state as well, or if they can continue to run, possibly at reduced speed.
“All of the components, throughout the entire line, communicate with each other without any intervention from a higher-level system or operator,” says Kaufleitner. “It would even be conceivable to create a self-validating line.”