Hi, it’s been a while 
How you do it is via the Rest API of the ISY. Essentially a URL with variable numbers assigned via ISY. example - http://userIPorDomain/isy/1/2/1 with the numbers being variables and commands being sent to those URLs. I realize this isn’t giving you a whole bunch to go off of but that’s all I can do a the moment (at work) but this should point you in the right direction. On Smarthings you do a Get HTTP command via webCore or via SmartThings app to trigger ISY actions.