Interface Circuit; Serial Interface Circuit - Brother PT-9200DX Service Manual

3.2.10 Interface Circuit

[1] Serial Interface Circuit

Fig. 3.2-12 shows the serial interface circuit.
This circuit is a 8-pin, RS-232C serial interface circuit for making connections
to a computer.
#2 is a RS-232C driver IC which converts logic level signals into RS-232C (+
and) signals.
The RXD signal is a print data input signal from the computer and transmitted
at a maximum baud rate of 115.2 Kbps.
The TXD and DTR signals are control output signals to the computer.
With the power on, P66 is switched to low to turn on Q6 (transistor) so that
the power Vcc is supplied to #2.
Fig. 3.2-12 Serial Interface Circuit
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