A programmable controller has a main processor and a scanner circuit in a unit that is connected through a multi-channel, multi-drop serial data link to a plurality of remotely located I/O racks. The I/O racks are adapted for connection to I/O devices connected to control a machine or process. The I/O...http://www.google.de/patents/US4413319?utm_source=gb-gplus-sharePatent US4413319 - Programmable controller for executing block transfer with remote I/O interface racks
