How to FTP only non empty files

Good day

I hope you can help me please.

I have an existing FTP script in place on my linux server that exports our csv data files from our RPAS MFP extract folder to another server

I need to include a check of file size to ensure that we never FTP 0 (empty) files across as it wipes out data on the server

Can you please advise on command to achieve that in our existing command below :

Thank you

#!/bin/sh

set -x

ftp -n -v $FTPHOST $FTPPORT << EOT

binary

user $FTPUSER $FTPPASSWD

prompt

put $1 $1

bye

EOT