---------------------------------
Within the .pm module
---------------------

package Serial;

require Exporter;
Exporter->import('import'); 

#Now declare what we permit to be visible within this module.
our @EXPORT = qw( &Serial_Init &Serial_TrxRcv &Serial_Close);

---------------------------------
Within the test .pl program
---------------------------
use lib '.';      # The Serial.pm is in the current folder

use Serial;       # use a "1 off type of macro expansion" of the Serial module

Serial_Init();    # Initialise the interface

---------------------------------