Can someone explain to me how "Download without Reinitialization" works?
I believe it allows me to keep my retained information when making changes to the DB without initialization to the start values. However, I have the box checked and it does not appear to work.
What can I change and not change without have to force reinitialization?
How do I get this to work?
The big trick with DL W/O Reinit is that you need to activate it and download it BEFORE you need to use it. Essentially the system is pre-creating a bunch of spare tags for you to use later, and hiding them from you until you actually use them, except that you get to use whatever data type you want.
As a side note, you said you want to keep "retained" information. If you meant "retentive", you need to create a special retentive memory reserve, with the 2nd field in your screenshot. If by "retained" you mean "whatever data my PLC currently has" then carry on.
Workflow could be something like:
1) Nearing end of project, turn on feature to minimize future impacts to production. Make one more DL.
2) You can no longer make changes to tags in DBs where it is activated, but you can add new tags.
3) at some point in the future, you need to add a couple tags. You add the tags to the DB, download, and your existing tags aren't affected. You have X amount less memory reserve available for that DB.
4) at some point in the future, you reinitialize the DB to get all the memory reserve back.
However, the most common thing that I run into is that people don't usually need to add a few tags to a DB. What I usually need to do is add a few tags to a data type, or expand an array of something. It's less helpful there.
In my view, this feature isn't good for a system being comissioned. It's helpful to activate when a system is being put into production and PROBABLY won't need more changes, but if it does they'll hopefully be small and you won't want to impact production.