One Panasonic SF-C21 can do the work of four safety relay units.Simple to wire the units in the control panel! Compact with a height 97 mm 3.819 in × width 45 mm 1.772 in. It's easy to find installation space for the SF-C21 unit. Four auxiliary outputs (PNP semiconductor output) are provided. Using RS-485 communications (MODBUS RTU), various general-purpose control units (PLC, HMI, etc.) can monitor the SF-C21 information such as the status, the selected logic, and any error status. Eight preset logics, safety-certified and compatible up to control category 4 PLe, can be selected by simply turning the rotary switch. Use our "Configurator SF-C" software to build your own safety circuits of connected devices, control logic, output modes, etc. No programming skills required! All possible logic combinations created with the "Configurator SF-C" software are already safety-certified by the certification bodies. The software also has a "simulation mode" to test if the prepared logic and safety circuit operates as intended. If the logic is not complete, the software will block its transfer to the SF-C21 unit.