In case it helps the conversation, here's the piston I use to open and close nine shades. I use a loop. Some open all the way, others almost all the way. Before closing, it checks a window sensor to ensure the window is closed first. If not, it doesn't close the shade.
There's a list of shade devices, a text list of window sensors, and a list of open positions. The window sensors and open positions need to be in the same order as the devices. There's also a settable delay between commands. The more blinds I add, the more I need to increase this. Otherwise, I'll get a shade or two that don't respond. 
