Panasonic KX-T7565AL, Service Manual

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8.4. DATA COMMUNICATION CIRCUIT
(1) FUNCTION
The data communication circuit serves the following functions:
Information exchanger between the DSHS and DSHS proprietary telephone, key input information as well as data for the LED
control, LCD control, etc. This information is continuously exchanged at all times.
(2) CIRCUIT OPERATION
When the DSHS proprietary telephone receives an IRQ signal from the DSHS and after sending the key input information to
the DSHS and receiving data for the LED control, etc., the DSHS proprietary telephone will return to the DSHS an acknowledge
signal.
(3) RECEPTION
The data from the EMSS is received via the H and L lines along the path shown below.
(4) TRANSMISSION
The data to the EMSS proprietary telephone is transmitted along the following path.
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KX-T7565AL / KX-T7565AL-B