DeviceHub is a tool which is supplied as part of the ASCOM Platform. It is a powerful tool for both routine use as well as disgnostic testing. It has many useful features such as traffic logging and its own set of "handset" controls for the telescope, dome, and focuser. There is a detailed help file for DeviceHub, accessible from the Start menu and DeviceHub's Help menu. You can find DeviceHub under the Windows Start Button, ASCOM Platform, Scope-Dome Hubs. We have Hall of Famer Rick Burke to thank for DeviceHub. Let's look at a block diagram of a typical usage:
In the illustration above, MaxIm DL's telescope controls are fed into DeviceHub, which calculates the proper dome slit azimuth for the mount geometry. DeviceHub passes commands from connected programs through to the drivers, allowing the programs to share the devices. Both MaxIm DL and Cartes du Ciel are controlling the telescdope and reading back its coordinates, etc. A slew from either MaxIm DL or Cartes du Ciel will cause the dome to immediately move to the proper new slit azimuth while the scope slews, maybe flips (without the dome stupidly following the scope around the wrong way). In the diagram, FocusMax could be attached to the focuser and telescope (for AcquireStar) as well. Of course a dome monitor could see through DeviceHub and report the status of dome rotation and shutter.
Any of the client programs on the left can be either 64-bit or 32-bit. DeviceHub itself is a 32-bit program, so it supports only 32-bit DLL type drivers. The device driver can be either a DLL type or an EXE type. Drivers that are EXE types may be either 32-bit or 64-bit. Most newer devices have EXE type drivers. If you encounter a 64 bit DLL driver (which device hub wouldn't be able to use), ask the device maker if they have a 32-bit version.