SNS STANDARD POWER SUPPLY INTERFACE

The SNS has developed a standard power supply interface for the approximately 350 magnet power supplies in the SNS accumulator ring, Linac and transport lines. Power supply manufacturers are providing supplies compatible with the standard interface. The SNS standard consists of a VME based power supply controller module (PSC) and a power supply interface unit (PSI) that mounts on the power supply. Communication between the two is via a pair of multimode fibers. This PSI/PSC system supports one 16-bit analog reference, four 16-bit analog readbacks, fifteen digital commands and sixteen digital status bits in a single fiber-isolated module. The system can send commands to the supplies and read data from them synchronized to an external signal at up to a 10KHz rate. The PSC time stamps and stores this data in a circular buffer so historical data leading up to a fault event can be analyzed. The PSC contains a serial port so that local testing of hardware can be accomplished with a laptop. This paper concentrates on the software for controlling the power supply. It includes an EPICS driver and the software to test hardware and power supplies via the serial port and VME interface.