Switch signal input interface circuit

In order to realize 4-way process switching signals
and 4-way system setting switch signal input interface
circuit. The process switch or level signal passes through
the optical isolator ICl (TLP521-4). After level conversion, it enters the three-state isolation buffer IC2 (74LS244) together
with the system setting switch signal , and is controlled by the address interface to communicate with the data bus. Lotus connection. The CPU needs to execute an interface input command to read the status of the eight switch signals of PO-P3 and SO-S3 through the bus isolator. In the computer control system, the system setting switches that need to be designed include "hard manual and soft manual switches", "forward and reverse action control switches", "control mode selection switches", etc.