Step 7 - Why have a block without Multi-Instance Capability?

When you create a Function Block in step 7 there is a ticky box for Multiple Instance Capability.

I understand what it is but wondered why you would ever declare a block without this ??

i.e. why is this even an option and not just enabled for every FB ??

Anyone any ideas?

Cheers

;-)

I think the main reason is backwards compatibility. Multi-instance capability have not always been around

Another reason is that Step 7 uses AR2 when calling a multiinstance block. When you declare an FB without Multi-instance capability address register 2 can be used more freely inside the FB.

ahhh... that makes sense. Thanks for the info Bratt. ;-)