STEP 7 Online Help

Type check for addresses

With this option you can toggle the type check for addresses as you enter them on and off (for example, with comparison or math instructions). The type check cannot be deactivated for bit logic operations and blocks and is independent of this setting.

CAUTION

The type check should only be deactivated by experienced users who are very familiar with the STEP 7 data types. Deactivating the type check does not mean that the addresses in the system are converted automatically to a suitable data type.
The type check is generally only deactivated in order to enter specific addresses which would not permit the type check in this form. If you open blocks saved originally without a type check at a later stage with the type check activated, the faulty locations in the block are not marked as being faulty. You cannot therefore tell by looking at a block whether it was saved with or without a type check.

 I hope this helps,

Hamid Hosseini