Program changeable sequence controller

摘要

A programmable sequence controller is disclosed which includes a controller memory having at least one read-only memory unit for storing a sequence program comprising a series of instructions each including an operation code and address information. An operation control device is also provided for examining an external input in accordance with an appropriate instruction. An input network permits application of external inputs designated by the address information to the operation control device, and an output network is provided for transmitting a control signal based on the examination result from the operation control device. A program input network including a read-write memory is provided for storing a part of the sequence program, which part is loadable in one read-only memory unit. A program changing device is provided for changing the partial sequence program loaded in the read-write memory, and a transfer system is included for immediately transferring the changed sequence program into a read-only memory unit.