Data Communication - Panasonic KX-DT543-B Service Manual

KX-DT543/KX-DT543-B/KX-DT546/KX-DT546-B
4.2.3.

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 from PBX is input to the comparator (pin 27) built in IC300 through Pulse Trans T300. The threshold voltage of the
comparator is determined by R306, R307 and R308. It is input into pin 26 and 28 of IC300.
The data to PBX is output from pin 32 and 33 of IC300, drives T300 by Transistor Q301 and transmitted.
IC300
ASIC1
PDX0
PDX1
PVRH
PDR 27
PVRL
Between Hand L
JK300(H-L)
PDR
IC300(pin 27)
PDX0
IC300(pin 33)
PDX1
IC300(pin 32)
Cch
From Format
SYNC
C308
R305
33
1 6
VDD33
E1 C1
2 5
B1 B2
3 4
C2 E2
Q301
DG
C307
R304
32
VDD33 VDD33
28
DG
R311
26
DG DG
TIMING CHART FOR DPT DATA COMMUNICATION
Parity
Dch
MAM B1 ch B2 ch
Received Data from PBX
C303
C305
T300
R302
1 10
2 9
VDD33
D301
8
1 3
2
DG
4 7
R303
5
C304
C302
Cch Dch
SYNC MAM B1 ch
Transmitted Data to PBX
125us / frame
8
L
JK300
D300 L301
2
4
3
4 1
L302
2
- +
1
3
6
C301
H
R T
PG
Parity
B2 ch
TO PBX
5
DG