Have you spoken to the manufacturer of the camera to see what your options are? Maybe they have a tool to accomplish this already or another way to trigger the function.
Also it may help if we knew the make/model of the cameras and the function you are trying to trigger.
On windows I think its possible to open a url in a browser and at least keep it minimized. You could then create a scheduled task to fire it off at whatever interval you like.
Once triggered, does the function require that the url/browser stay open to complete?
EDIT: to clarify are you on Windows or Linux from which you need to do this?