Gambit

As for field wiring i like CC-Link IE Field maybe not as popular as most but you can use star and line topology together as much as you like so you don't really need to take care. It's 1GBps uses standard CAT cables and you don't need switches.

Yep, but you only need to clear the memory if you run into memory problems. It's ok if the other file exists 

With Tree you mean thr tree in your software ? because there you will only have Station 1 But in the PLC it will contain both MAIN0 and STATION1. (It's just another file and not over written as it has a different name) As @Crossbowmentioned this does take memory in the PLC so it is better to clear the PLC (remove the old files)  before you download the new files. Juts look at it like a PC. if you copy a word document to your C drive but there is already a word document with the same name than it will overwrite that file. If it has another name then you will have two word documents.  Remember the PLC will only run the program files which are in the PLC parameters.  

Can you make a screen capture with the monitored values so we can see the settings?

The structured program can't be downloaded into an FX3S only the PLC code. But you should be able to upload that and open it

It's the same like a harddrive if your file is called prog 1 on the drive and copy a new file call prog 2 then they both exist on the drive. In case of the PLC only the program(s) set in the parameters will be executed. 

You will have to rename them and write them to the PLC. These names are set in your PLC Parameters!!!. Also if you rename these files and download them to your system Q your files will not be overwritten as these have other names so they will still be on the system Q.  

If you have registered your current version at the Mitsubishi site than you should be able to download the update. Otherwise contact the Mitsubishi Dealer in South Africa -  adroit http://www.adroit.co.za/

Have you taken a look at chapter 24(High speed input/output functions)  of the iQ-F user manual application. It's in the e-manual viewer  

Download the latest version

Do you mean 12.1?

I think the Keyence vision system supports MC protocol. Than all you need to do is set up an ethernet port and set up the devices in the keyence

Sounds like you didn't configure any devices to your variables in GX Works 2

So your question is how to convert an integer value to a string? INT_TO_STRING(_E)

A download or online change of the compiled program should be enough.  When it's a new program file you will have to download the parameter and reset the PLC as the PLC parameters have changed.