Wireless protocol for machine safety
Among the innovations launched at the Hanover Fair was a wireless safety foot control based on a new communication protocol, bringing distinct advantages compared to conventional solutions.
The application of wireless switchgear offers advantages because these devices are flexible to position and easy to mount - wherever the operator can monitor the process most easily. Wireless devices can deliver benefits in two of the key machine operational modes - set-up and process monitoring. The machine engineer can also make use of these advantages for safety switchgear - applying safety foot switches, for example, which communicate via a safe wireless protocol.
Steute has just developed just such as safe protocol. The two-channel wireless technology, called sWave 2.4 GHz-safe, is characterised by high reliability and very good coexistence with other wireless systems. In addition, interference-free parallel operation with other systems at a high system density is possible. The basis for this high transmission safety is a pseudo-random frequency hopping procedure. The hopping pattern is only known by the corresponding transmitter and receiver. Radio signals are evaluated by a compact combination of wireless receiver and safety relay module which can be installed inside the control cabinet.
The first switchgear equipped with the sWave 2.4 GHz-safe technology is the RF GF(S)I 2.4 GHz-safe-b safety foot switch, which can be actuated tirelessly thanks to its ergonomic design. The version with a cable has already been tried and tested in many different machine safety applications. The new version that eliminates the cable means that the foot switch can be positioned with far more flexibility - wherever the operator can monitor the process most easily - and eliminates the potential tripping hazard of a trailing cable which could effectively restrict industrial safety.
A typical application for the new wireless safety foot switch is a safe setting mode for machines with an opened protective guard. As long as the machine operator is actuating the foot switch, the machine can be operated in setting mode while the protective guard is opened. Unlimited movement is possible because neither the operator nor any colleagues are disturbed by cables lying on the floor. This type of operation also has many advantages for the programming of robots, the operation of machines with big movable components like e.g. wire machines and presses, as well as for the exchange of appliances on big machine tools. The wireless connection is maintained as long as the operator is actuating the foot switch. Evaluation is performed by a compact combination of wireless receiver and safety relay module which can be housed in a switchgear cabinet.
The type test for the system comprising a wireless foot control and a receiver unit according to ISO EN 13849-1 in Performance Level (PL) d and Safety Integrated Level (SIL) 2 according to IEC 62061 is in preparation. This categorisation documents reliability of the safe wireless signal and suitability for safety-related applications.
Other sWave wireless products on show from Steute at the Hannover fair included the RF BF 74 control devices. Switching inserts and differently coloured types of push-button caps with inscription can all be combined with various push-buttons, key switches and rocker switches. Users can select housing versions for one, two or three switches. And if more than three control elements are required, larger housings are also available.
The RF GF(S)I 2.4 GHz-safe-b safety foot switch and other Steute products are available in the UK from ForTop.
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