Machine Expert – Safety provides help on firmware functions/function blocks.
Specific (context-sensitive) help on FB/FU can be called
from the context menu of blocks which are already inserted in a worksheet ('Help on FB/FU' item).
using the Edit Wizard: in the Edit Wizard selection area, right-click on the desired FB/FU and select 'Help on FB/FU' from the context menu.
in the 'Function/Function Block' dialog: in the dialog drop-down combo box, select the desired FU/FB and click the '?' button.