PI (Physik Instrumente) LP (Auburn, MA) offers the C-884 4-axis digital servo controller for motorized linear translation stages and rotary positioners with very high accuracy and repeatability. The high-speed encoder interface allows the use of direct-metrology linear and angular scales with resolutions down to the nanometer and microrad realm and below. The controller is equipped with a dual-core architecture for fast servo handling and command interpretation. Software tools are provided, including PIMikroMove software that does not require writing code.The General Command Set (GCS) simplifies the development of custom applications. The GCS commands are available at the controller terminal, in macros, and in the form of a universal driver set for LabVIEW (VIs), Windows dynamic link libraries (DLL), and Linux libraries. The controller supports several motion profiles, linear vector motion, and point-to-point motion. PID parameters can be changed on the fly, and the servo update rate is 20 kHz. Communication is through industry-standard TCP/IP, USB, and RS-232 interfaces.