USI Standard

USI: a Universal Standard for Instrumentation

Julien Gonthier, Nadir Belkhier, Eddy Lelièvre-Berna
Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France

The number of sample environment equipments grows and gets more and more complex. At a large facil- ity, their installations on the instruments require a rigorous organisation with well-known calibration curves, PID parameters, limits, communication protocols, etc. To reduce the costs, we employ as much as possible standard electronics that can be used with several equipments.

This organisation may lead to troubles: a sensor has been replaced but its calibration curve is not available in a known format; one has forgotten to change the limits and the indium seal will certainly melt in the coming days; the field requested is not the one expected because the power supply has been used with another magnet; etc.

We propose to limit these problems by developing and adopting a USI standard: a protocol that makes trans- parent the communication between equipments and electronics, analogous to the USB between peripherals and computers. A USI certified equipment contains the information necessary to reset a list of electronics. For example, it suffices to plug a cryostat to reset the temperature and cold-valve controllers and the level monitors.

To achieve this, one connects a USI controller to the existing electronics and adds a USI interface to each equipment. We present a draft of the USI protocol and its implementation. We also show how it can be inte- grated in a unified control software.