Method for addressing variables in a distributed automation system

摘要

The method involves transmitting a variable (ANNA) as address data to a program controlled sub device (SPS) by another program controlled sub device (HMI). A characteristic value (ID1) associated to the variable is automatically generated during defining the variable from the former sub device. A test value (CRC) about the address data of the variable is determined and compared with another test value transmitted by the latter sub device. A value of the former variable is released by the former sub device only when the value correlates with the former test value.