MC70 Pistol Grip

We have many MC70xx units in the field, I'm attempting to update our software but cant figer out how to control/read the pistol grip trigger

 

I assumed it automatically triggered a soft key press when the scanner module is active but I get nothing from the unit. pressing the soft scan buttons act as normal and the scan head scans correctly

I'm currently working with EMKD 2.9 under VB2008

is their any code of test software to prove the units are not faulty

 

many Thanks

Derek