The mark of true safety
When TRUMPF began development of their mobile marking laser, they planned to develop the safety solution in-house as well. Those plans changed, however, when B&R introduced its low-cost, integrated safety solution – SafeLOGIC-X. It was exactly what the laser specialists had been looking for.
The broad spectrum of applications for TRUMPF industrial lasers include welding, cutting, microprocessing, surface treatment and marking. When engineer Matthias Kauffmann began working at TRUMPF in 2013, his first development project was a new mobile marking laser. The goal was to outperform the small number of other devices on the market in terms of quality and safety. This would be no small feat, considering it was the first marking laser TRUMPF had ever produced.
A matter of safety
Unlike stationary marking lasers, with a mobile unit the user can't simply shut a safety door. TRUMPF would therefore have to use a partial vacuum to ensure that the hand-held marking head is pressed securely against the surface to be marked. In the event of incomplete contact, the laser must either shut off or be prevented from firing in the first place. "The big questions were therefore: Which sensor signals should we use on the hand-held unit, and how should we use them? What do we need to monitor, and what conditions do we need to rule out in advance? These questions framed the entire development process, especially since a primary goal was to achieve Laser Protection Class 1 certification for the marker. This means that users aren't required to use protective eyewear, even when working with the laser," explains Kauffmann.
Develop our own safety controller?
"B&R did a large portion of the development – actually, more than we had initially planned. Our starting game plan was to use a B&R controller, but just the logic. We would develop the safety inputs – the board in the hand-held unit – ourselves. In other words, our team would handle everything that had to do with POWERLINK and openSAFETY. We have some really good electronics and safety engineers, and the certified safety cutoff solution for our lasers achieves the highest performance level. So we definitely have the know-how," says Kaufmann.
Pleasant surprise: SafeLogic-X arrives on the market
Know-how alone was not enough, however – the clock was ticking. One of the main reasons TRUMPF had even begun the in-house development in the first place was that the market at the time didn't offer a low-cost safety PLC for small-scale safety applications. Still, TRUMPF was on the lookout for alternatives. According to Kaufmann, since the application's pressure sensors meant the use of analog inputs, the field narrowed quickly. Automation specialist B&R stood at the very top of the list of safety technology providers. When B&R introduced the first prototypes of its SafeLOGIC-X in 2013, the new solution was a perfect fit for TRUMPF's project. The software-based safety controller offered all the advantages of the integrated safety solutions that had previously been out of reach due to their price.
"With B&R's SafeLOGIC-X, all the advantages of integrated safety technology are finally available to smaller applications as well. This solution covers it all – from safe I/O and drive technology to integrated diagnostics, safe line integration and safe machine options." Paolo Salvagno, Managing Director, B&R Switzerland
Surprisingly simple safety solution
Behind the SafeLOGIC-X lies a solution that can compete with a conventional hard-wired safety relay in its simplicity. The X in the name hints at the big secret: this safety controller doesn't need any hardware. All of the safety functions are distributed across hardware components that already exist on the network. The safety application itself runs on a safe input module, while all parameter and configuration management tasks are handled on the standard controller. Safe user interface functionality is even handled by the HMI application. The unique architecture of the SafeLOGIC-X is made possible by the openSAFETY standard. This safety protocol provides communication services that comply with SIL 3 requirements and ensures that parameters and configuration data are safely distributed and monitored over the entire network. Since it doesn't require a hardware safety controller, this solution is also referred to as a "virtual safety controller".
"The word 'virtual' can mean everything – or nothing at all."
B&R's virtual safety solution – SafeLOGIC-X – now brings all the advantages of integrated safety technology to smaller, cost-sensitive applications as well. Implemented entirely in software form, SafeLOGIC-X eliminates the need for a hardware safety controller. The safety functions are distributed across hardware components already found on the network – like input modules, standard controllers and HMI devices. When a system outgrows its SafeLOGIC-X solution, it is no trouble at all to switch to a dedicated SafeLOGIC controller without any reprogramming. This scalability guarantees system continuity while also ensuring a uniform approach to engineering and diagnostics
Interview with Matthias Kaufmann, development engineer at TRUMPF
Mr. Kaufmann, what was your impression when you first heard about this virtual safety solution?
"Well, the word 'virtual' is thrown around a lot. It can mean everything – or nothing at all. In this case, though, with the safety controller distributed over multiple components so that you no longer need a physical device, it makes a lot of sense. Knowing what must have been involved in developing such a solution, it is certainly quite an accomplishment. I've got to say, what B&R has done here is impressive."
As a pilot customer, you were one of the first developers to work with SafeLOGIC-X.
"That's right, and it's pretty interesting how it all happened. When we first got serious about SafeLOGIC-X, we had all the most important information and technical data, but still no physical product. So I developed the software on a SafeLOGIC first and then ported it. For us, the important thing was knowing that the module was indeed coming and what it would be capable of. Of course, there are some products where you don't want to be a pilot customer, but with a safety controller we knew it would be certified and were confident that it would work as promised. Based on our past experience with B&R, we knew we would be happy with the results."
Did you consider going with B&R's classic safety PLC, the SafeLOGIC?
"To be honest, the SafeLOGIC would never have fit into our housing. That's why we were so pleased to know the smaller and cheaper SafeLOGIC-X was on the way. It's exactly the right product for us. Our marking laser doesn't need more than a small safety solution. Sure, we have the analog value to deal with, but only four safe digital inputs, which is very little compared to other machines. From a computational standpoint, a SafeLOGIC controller would have been overkill."
How the mobile marker works
The first thing you notice about the TruMark 5010 Mobile Marker – TRUMPF's new mobile marking laser – is its hand-held marking head, which the operator simply presses against the desired component in order to mark it. The TruMark 5010 Mobile Marker complies with Laser Protection Class 1. The safety solution monitors and assesses a variety of physical parameters.
The airtight seal on the hand-held marking head ensures that no laser radiation can escape. When the operator presses the marking head against the desired component, a partial vacuum ensures a tight seal, which is monitored by the safety application. If the head is not pressed properly against the component, the intelligent built-in sensors detect the poor seal and prevent the laser from firing.
A further advantage is the exhaust that is integrated in the head, which removes any vapors or loose material generated in the course of marking. The laser beam is transmitted to the scanner unit via a fiber optic laser cable. At the core of the TruMark 5010 Mobile Marker is a pulsed fiber laser with a high peak power in the infrared range. Together with the base unit, which houses the controllers for both the laser and the safety technology as well as the exhaust unit, it is mounted on a mobile cart. (Source: TRUMPF)
The advantages of SafeLOGIC and SafeLOGIC-X
The SafeLOGIC-X solution is programmed using the SafeDESIGNER editor in Automation Studio, just like the hardware-based SafeLOGIC solution. This means that when a system outgrows its SafeLOGIC-X solution, it is no trouble at all to switch to a dedicated SafeLOGIC controller. The safety applications can be scaled and configured to meet the requirements of systems of any size. As safe input and output modules are added to a SafeLOGIC safety controller, existing programming code can simply be reused without having to make a single change. Switching over also doesn't require recertification, another benefit that saves both time and money.
This type of unlimited scalability guarantees system continuity right from the start while also ensuring a uniform approach to engineering and diagnostics – two factors vital to increasing the availability of systems and machines.
The architecture used with SafeLOGIC-X is made possible by the openSAFETY standard. This safety protocol provides communication services that comply with SIL 3 requirements and ensures that parameters and configuration data are safely distributed and monitored over the entire network.