I think we need to learn more about your application. What instrument vendor and model are you using? When you say that the subVI connects for two seconds, is the two seconds spent inside of the ActiveX object, or are you doing something in the subVI to wait two seconds? If the two seconds is being spent in ActiveX, there's probably not much you can do about it (unless you are willing to not use the ActiveX object and just talk to the serial port directly). Note also that the measuring device itself may take two seconds to do any measurement. In that case, you can't go faster without replacing the device.
Brian
