merker bit vs Data blocks

what is the difference between merker bit and data block.

Merker is german for "marker" and used as a memory BIT. A Data BLOCK is a block that can store a value. In a sense, a merker BIT (such as any other bit) is digital, while a data block in a sense, is analog.

M bits are like software duct tape! Only use them when you are doing trouble shooting or quick fixes.

Depending on processor the first 16 or so bytes of m bits will be retentive.

On higher level CPU's all Datablock values are retained (300's and 1500's) but I don't believe they are on the 1200's.

As a best practice use DB bits whenever possible. They are much more portable.

I think the more correct translation for Merker is Flag and it escapes me how you see things in a Data Block as analog.

It has bits like DB1.DBX0.1 and bytes like DB1.DBB2 and words like DB1.DBW4, basically.

Just like you use "internal" PLC memory.

on top of that you can use convenient things like structures, arrays and User Defined Types.

When using FB's, DB's are used to store its In, Out and Stat addresses

Thank you so much guys