The design of matrix board based on PXI bus

PXI (PCI eXtention for Instrument), a new and open bus architecture, has the characteristics such as the stable mechanical structure, the reliable electronic performance, and the easily expandable software. A lot of hardware, drivers, operation systems, and application programs adapted to PCI bus are available. Matrix board, a common module in industrial detection, can be used to monitor a large number of switch signals. In matrix board design, however, shielding disturbance and isolating signals are two main problems to be solved. A design method of matrix board based on PXI bus is recommended in this paper. In the design a special photoelectrical isolation circuit is employed to minimize the interference, and 81C196KC SCM (Single Chip Microprocessor) is used to control the module. The interface compounded of CPLD and ASIC between PXI bus and the matrix board makes full use of the current hardware resource available. In addition, the driver conforming to VISA (Virtual Instrument Software Architecture) is' programmed in Visual Basic and C. Taking full advantage of the good electric and easy extension characteristic of PXI bus, this module and realizes the data acquisition of 256 switch signals reliably.