Synchronize only new and updated files

I want to synchronize the remote directory with the local directory in a script.
I am using the command
It appears if I run the command a second time (right after the first time), the same files get transferred. How do I configure the script so only new or updates files get transferred and unchanged files are ignored?

Thanks

Please start here:
https://winscp.net/eng/docs/faq_synchronize