Read Panasonic KX-DT321UA Service Manual online
12
KX-DT321UA/KX-DT321UA-B
4.2.7.
DXDP Communication
Function:
This circuit performs the same type of communication as between the DPT and PBX, but for a DXDP-compatible DPT con-
nected to the DXDP port.
In addition, power feed is also controlled.
nected to the DXDP port.
In addition, power feed is also controlled.
Circuit Operation:
The data to the slave DPT is output from pins 33 and 34 of IC2 and sent via the pulse transformer T2 to JK2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 31) built into IC2.
The threshold of the comparitor is determined by R101 to R103, which is input into to pins 30 and 32 of IC2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 31) built into IC2.
The threshold of the comparitor is determined by R101 to R103, which is input into to pins 30 and 32 of IC2.
Power is supplied to the Slave DPT by means of a constant current circuit Q5 and Q6 as below:
• IC2 pin 28 H: Constant current circuit ON.
• IC2 pin 28 L: Constant current circuit OFF.
• IC2 pin 27 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 27 L: 20mA feed (initial supply to Slave DPT).
• IC2 pin 28 L: Constant current circuit OFF.
• IC2 pin 27 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 27 L: 20mA feed (initial supply to Slave DPT).
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