Main And Interface Pcbs; Interface; Rs232C - Star Micronics TSP400 Series Technical Manual

2.

Main and Interface PCBs

The main PCB and interface PCB provide the drive circuitry for the TSP-400 printer series. The two boards are connected
via 40-pin connectors.

2-1. Interface

2-1-1. RS232C interface
CN3
DTR
R-CH
TXD
RXD
CTS
Data flow from host to printer: IC1 receives serial data from the host computer via RXD, converts the signal voltage
from RS232C level to TTL level, and passes the result to the CPU. The CPU converts the serial data to parallel and stores
it into buffer memory.
Data flow from printer to host: The CPU generates data, converts it into serial form, then passes it to IC1. IC1 converts
the signal voltage from TTL level to RS232C level, then outputs the result over the TXD line.
The CTS line is hardware-connected, but the connection is not recognized by software. (The printer does not monitor the
signal.)
IC1
D2O D2I B12
D1O D1I B14
R1I R1O A15
R2I R2O B15
HD151232FP
RS232C Interface PCB
Fig. 2-2 RS232C Interface
– 21 –
THEORY OF OPERATION
IC10
CN1 CN9
Gate array
B12
ACK
B14
A15
B15
Main PCB
IC5
CPU
TXD0
RXD0
RXD1