Data Communication Circuit - Panasonic KX-T7730X Service Manual

KX-T7730X
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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