Interface Circuit - Brother PT-2500PC Service Manual

3.3.4

Interface Circuit

Fig. 3.3-5 shows the interface circuit. This 8-pin interface port serially receives print data
from the connected PC.
Driver IC (ADM202, #1) converts the TTL logic level signals to the RS-232C compliant
signals (+12V and -12V), and vice versa.
RXD is an input signal line to receive print data from the connected PC, which enables
high transmission rate up to 115.2 Kbps. TXD and DTR are control signals to be
outputted to the PC.
When the machine is powered on, the POW signal line goes Low, turning transistor Q8
on and feeding Vcc power to the driver IC (#1).
Fig. 3.3-5 Interface Circuit
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