Didn't I answer this last night? (With basically the same answer that someone else had already given?)

There isn't a way to do it with the serial models.

On Sun, Nov 18, 2012 at 6:28 PM, Juan Carlos Galarza Roca <jcgalarzar@hotmail.com> wrote:
Hi all
Is there a command line psrameter to get a Garmin Etrex serial number?
I ve tried gbsbabel.exe -D1 -i garmin -f com1 with no results

Please help