Kern Communications Protocol (KCP) is a bi-directional protocol available on more and more Kern scales. Version 0.8.1 of 232key Pro allows you to select a “Kern KCP” device in the Input tab and to easily set the “SI” command (“send immediately”) in the Control tab to request the weight:
Further information on the Kern Communications Protocol can be found in this PDF document.
Kern has also produced a video showcasing the protocol (using their BalanceConnection software, not 232key Pro):
KERN Communication Protocol | KERN KCP