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10.6. DATA COMMUNICATION
Function
The data communication circuit serves the following functions:
Information exchanger between PBX and proprietary telephone, key input information as well as
data for the LED control, LCD control, voice data, etc. This information is continuously
exchanged at all times.
Circuit Operation
The data received from PBX is inputted to the comparator (pin 36) built in IC2 through Pulse
Trans T1. The threshold voltage of the comparator is determined by R101 to 103 and inputted to
pin 37 and 35 of IC2.
The data to PBX is outputted from pin 38 and 39 of IC2, drives T1 by Transistor Q1 and
transmitted.
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