Beckhoff has developed a safety PLC that fits into a standard 12mm-wide EtherCat I/O terminal block housing, thus saving space and giving positioning flexibility. The EL6900 safety PLC terminal offers 256 programmable function blocks and can be connected to up to 128 bus-based safety devices.

The safety PLC is suitable for applications up to SIL 3 and conforms to IEC 61508 and EN ISO 13849-1 PL e. Installations can be expanded using more of the safety PLCs, allowing safety control tasks to be implemented either locally or centrally.

The safety PLC can be used as a safety controller for Beckhoff’s AX5000 servo drives, which use EtherCAT as a motion bus. Safety sensors and actuators can be connected using 24V DC digital input and output terminals. The safety function blocks can be configured to offer functions such as emergency stops, safety door monitoring, muting and two-hand control.

The safety PLC terminal can be replaced easily without needing to reload and verify the program. The configuration is loaded automatically and verified by the system. A tool is provided for calculating and determining the SIL or PL level. The system uses the open Safety over EtherCAT protocol to exchange data securely using a choice of media.