Programmable controller having interrupt controller for determining priority for interrupt requests from a plurality of I/O devices and generating interrupt vector

摘要

Data lines constituting a data bus for connecting a plurality of parallel I/O devices are assigned in a one-­to-one correspondence with the I/O devices. Each I/O device outputs an interrupt request to a CPU (1) through an interrupt request line. In response to an interrupt enable signal from the CPU, each 1/0 device (30a, 30b) supplies information indicating its mounting position to an interface circuit as interrupt data through a data line of the data bus assigned to itself. The interface circuit has a latch circuit (100) for latching interrupt data from the plurality of I/O devices, a circuit (102) for setting the priority of interrupt data latched by the latch circuit, and a circuit (104) for generating an interrupt vector on the basis of interrupt data having the highest priority in accordance with the set priority order.