7.3. DATA COMMUNICATION CIRCUIT
Function:
The data communication circuit serves the following functions:
Information exchanger between the PBX and proprietary telephone, key input information as well
as data for the LED control, LCD control, etc. This information is continuously exchanged at all
times.
Circuit Operation:
When the proprietary telephone receives an IRQ signal from the PBX and after sending the key
input information (19 pulses) to the PBX and receiving data (47 pulses) for the LED control, etc.,
the proprietary telephone will return to the PBX an acknowledge signal.
1) Reception
The data from the PBX is received via the H and L lines along the path shown below.
H, L Line D2 T2 R106 Q102 IC2 IC1 Pin 18
2) Transmission
The data to the proprietary telephone is transmitted along the following path.
IC1 Pin 16 IC2 Q101 T2 D2 H, L Line
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