This is a question I get asked quite a bit.
And that's probably because it's not the easiest question to answer.
Option 1: The Application Archive
If you have this file, most of the time you'll be able to extract it back to a project using the Application Manager.
However, there are a few things that could stop this from working successfully.
First, if your View Studio ME software is older than the version used to create the APA, well then you're not going to be able to open and edit that project.
In that case your best option is to get software at least as new as version used to create the .APA.
The second problem you may run into is when you try to open an old pre-6.1 project created on a Windows 32bit OS on a new Windows 64 bit OS.
Unfortunately, the old project database can't be exported on a 64 bit OS, so if you're in this situation you'll want to read my previous articles on this subject:
Option 2: Runtime Files
Old runtimes files that are pre-version 5.0 just don't have all the project components saved in the .MER file.
In other words, while there is a way to recover tags and graphics, as I discuss in this article there is no way to recover Alarms, Parameters, Macros, and the RSLinx Enterprise communications setting from these legacy .MER files.
However, if you are fortunate enough to have a .MER file created with version 5.0 or greater, there is a chance you can restore the application from the .MER file using the Application Manager.
The determining factor is whether the person who created the .MER file (1) allowed conversion, and (2) passworded the file.
If the .MER was created without allowing conversion, there's no way to recover the project from the .MER file.
If the .MER file requires a password, you must have that password in order to recover the project from the .MER file.
On top of those considerations, you'll also have the same 32 bit / 64 bit OS issue with .MER files that I mentioned above with .APA files.
So if your .MER file was created in a pre-6.1 version of View Studio on a 32 bit Windows OS, you'll need to first use the Application Manager to recover the .MER file on a 32 bit Windows OS before following the 32 bit to 64 bit conversion process I discuss in the articles I link to above.
I hope you've found today's article helpful.
If you have any questions about what I've written please don't hesitate to post them using the “post a comment or question” link below.