ASi-SaW

The AS-Interface Safety at Work safety bus system has been tried and tested for a long time. Both operational and safety-related signals can be transmitted via the yellow ASi ribbon cable. This has advantages for the manufacturer of the plant (less installation effort, more flexible configuration) and also for its operator, who can, for example, evaluate the operating states of the safety switchgear in more detail. Another advantage is the comprehensive diagnostic functions, which allow the source of the fault to be located quickly in the event of irregularities or malfunctions.

SD bus

The SD-Bus developed by Schmersal for collecting status and diagnostic data, such as limit and temperature warnings and internal faults, has also proven its worth. The control of the guard locking function and the adjustment of the locking force is also possible via the SD bus. This data is read or written cyclically by an SD gateway or by the Protect PSC1 modular safety controller. In the (near) future, the functions will be further expanded - for example, to include an electronic nameplate and additional status, diagnostic and operating data. This creates the prerequisite for a much simpler networking option with higher levels - via OPC UA as a standardized protocol for M2M communication.

Safety Fieldbox

An alternative to the AS-i SaW safety bus is the Safety Fieldbox System (SFB) developed by Schmersal. Each field box allows the connection of up to eight safety switchgear and operator panels (BDF series) of different designs in the field. Electromechanical and electronic safety sensors and solenoid interlocks each occupy only one device connection. Both the safety-related and the operational signals are collected and connected to higher-level control modules via Profinet/Profisafe.

Three solutions

These three wiring concepts are cost-effective and equally simple solutions that can be installed according to the plug&play principle. In addition, these solutions are very flexible when it comes to adapting to the individual safety requirements of complex systems and machines. Moreover, the additional transmission of all diagnostic signals from the connected devices provides optimum process transparency. And what is becoming increasingly important as an argument: Because fewer cables are needed, bus systems and network solutions save expensive (and scarce) resources such as plastic and copper.

Author: Christian Heller, Head of Product Management