You mean you don't get Argument "12,23" isn't numeric in chr? I have very low tolerance for people don't help themselves by using use strict; use warnings;.

That code snippet you are using was used to demonstrate that utf8::downgrade works regardless of the internal format of a string. It's not a solution to your problem. If anything, the other snippet would be more relevant since you have text.

If $coords had contained bytes (already encoded text or packed/binary data, etc), the solution would have been utf8::downgrade.

Since $coords contains text, the solution is Encode's encode.

use Encode qw( encode );

$sftp->write( $waytemp, encode($enc, $coords) );
[download]

Replace $enc with the encoding you desire to use.