Detection System, Based On The Can Bus Of The Superconducting Magnet Power Supply Temperature

Superconducting Solenoid Magnet(SSM) is one of the most important components of BESIII. It provides an axial magnetic field of 1.0T with a good field uniformity over the tracking volume. Particle detectors within this volume will measure the trajectories of charged particles emerging from the collisions. A Power Supply is needed to provide current for SSM.The Power Supply of SSM provides 4000A current for the magnet.The temperature almost reaches 70℃. It is necessary to monitor the state of the power supply. This paper discusses the advantages of CAN-bus, analyses the interface and function of each main sensor, brings forward the methods of multi-channel and multiple point temperature measurement using of 1_wire bus. Based on the CAN-bus, the monitor system was designed and realized the automation of data collection.Sensors are the key part of the monitor system. In this paper, interface and function of sensors was analyzed, as the foundation of electronic circuit and the programming.In the part of the electronic circuit design, the main processor is Microchip PIC18F248, there is an ISO CAN-bus module inside this chip based on CAN 2.0B protocal. Adjustable circuit for sensors was designed and a proper method was adopted to improve I/O driven ability. Common-mode coil was added to decrease noise. A circuit to measure the rotation speed of cooling fans, a real-time clock and the interface of CAN-bus was also designed. The functions were programmed.By using Lab VIEW and with a CAN-bus interface card in the computer, all the data are acquired. The histogram and warnings are displayed and refreshed in real-time.