Technical data

Basics of Creating Logic Blocks
10.5 Editing LAD Elements in the Code Section
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 257
• Coils which do not permit Boolean logic:
- Master Control Relay Activate _/(MCRA)
- Master Control Relay Deactivate _/(MCRD)
- Open Data Block _/(OPN)
- Master Control Relay Off _/(MCR>)
All other coils can either have Boolean logic operations or not.
The following coils must not be used as parallel outputs:
• Jump if Not _/(JMPN)
• Jump _/(JMP)
• Call from Coil _/(CALL)
• Return _/(RET)
Enable Input/Enable Output
The enable input "EN" and enable output "ENO" of boxes can be connected but this is not
obligatory.
Removing and Overwriting
If a branch consists of only one element, the whole branch is removed when the element is
deleted.
When a box is deleted, all branches which are connected to the Boolean inputs of the box are also
removed with the exception of the main branch.
The overwrite mode can be used to simply overwrite elements of the same type.
Parallel Branches
• Draw OR branches from left to right.
• Parallel branches are opened downwards and closed upwards.
• A parallel branch is always opened after the selected Ladder element.
• A parallel branch is always closed after the selected Ladder element.
• To delete a parallel branch, delete all the elements in the branch. When the last element in the
branch is deleted, the branch is removed automatically.
Constants
Binary links cannot be assigned constants (i.e. TRUE or FALSE). Instead, use addresses of the
data type BOOL.