connect scale machine to dynamic nav 2009 proplem ayncronusly

Hi guys can any one help me i have scale weighting machine i need to connect dynamic nav 2009 with this machine .meaning when i take weight to machine showing in dynamic nav purchase order can i do this .

I can do this by .net serial port (c#) using timer but i don’t know how to connect this asynchronously with dynamic nav 2009

my code is .

thanks