Function blocks (FBs) belong to the blocks that you program yourself. A function block is a block "with memory." It is assigned a data block as its memory . The parameters that are transferred to the FB and the static variables are saved in the instance DB. Temporary variables are saved in the local data stack. Data saved in the instance DB are not lost when execution of the FB is complete. Data saved in the local data stack are, however, lost when execution of the FB is completed.