Modular controllers for piezo-driven nanopositioning systems have been introduced by PI (Physik Instrumente) LP. The E-621.CR systems have high-bandwidth analog and networkable digital interfaces and comprise a low-noise piezo power amplifier, a high-speed servo controller, precision 20-bit A/D and D/A converters, and sensor electronics for absolute-measuring capacitive nanopositioning sensors. Three versions are available to support piezo positioning systems with strain gauge, inductive and capacitive sensors. They can be operated as stand-alone systems or can be plugged into a chassis with up to 12 slots for multiaxis applications. They also are suitable for scanning and alignment tasks in optics, semiconductor technology and photonics packaging.