The Endat 2.2 subsystem consists of an encoder with serial transmission protocol at a maximum frequency of 16 MHz, a data transfer line, and a receiver with monitoring functions.  The ExN 425/427 and ExN 1325/1327 safety-related position encoders are inspected for compliance with ISO 13948-1 and IEC 61508. Reliable transmission of the position is based on two independently generated position values along with any corresponding error bits.