The GPP series models 
provides user with a 
programmable external 
trigger port, which is used 
to dock certain functions 
control. 
It can turn each Data Line 
(D0,D1,D2,D3,D4) into input signal 
respectively to have command of the 
following four functions: 
1. Control of channel On/Off 
2. Control of Tracking mode 
3. Toggle between PWR/Load modes 
4. Toggle between CC/CV/CR modes 
under Load