The execution of the function blocks contained in a structure block can be controlled by the bit input of the Enable-SB block. If the input signal P is 1, the target system functions of the contained blocks are called. At value 0 the block functions are skipped.
The Enable-SB block is placed at the lower right corner if it is dropped over the symbol of a structure block during inserting. The block is connected to the structure block until it is erased, i.e. operations like moving and copying are automatically executed with both blocks.
At disabled structure blocks the last calculated values are provided at the outputs.
By enabling and disabling structure blocks the runtime of programs can be reduced considerably. For example with sequence controls it is useful to enable or to disable program parts over the bit outputs of the step blocks