Programmable control system test unit - provides fast access to signals on controller input-output connections

摘要

A test equipment for a programmable control system is designed for fast convenient examination of the signal conditions in the channels between the controller and the connected peripheral units. Each of the input and output connections of the programmable controller are selectable using a switch and logic circuit. The selected connection is gated to a display element on which its binary state is examined. The signals on the controller connections may be routed via a decoder circuit either to the display device or to a processing unit over a single bit channel controlled by a switch. The decoder is controlled either via address switches or from an instruction register as determined by a s et of switches operated in conjunction with the single bit channel switch.