2-1-2.Rs-422A Interface - Star Micronics TUP400 Series Technical Manual

2-1-2. RS-422A Interface
CN3
RD (+)
RD (–)
CS (+)
CS (–)
RS (–)
RS (+)
SD (–)
SD (+)
Data flow from host to printer passes from the RD terminal to the IC1 on the interface board and is input to the CPU.
The IC1 converts the RS-422A and TTL voltage levels.
The CPU converts the input serial data to parallel data and stores that data in the memory buffer memory. It also converts
the internal parallel data to serial data and outputs that to the IC1.
IC1
+
R2I
+
D2O
–
R2I
–
+
R1I
+
D1O
–
R1I
–
D2EN
D2O
D2I
D2O
D1EN
D1O
D1I
D1O
MC34051
RS-422A Interface Board
Fig. 2-3 RS-422A Interface
CN1 CN9
A15 A15
B15 B15
A10 A10
B12 B12
B14 B14
– 19 –
IC10
Gate
Array
ERROR
ACK
IC5
CPU
RXD0
TXD0
RXD1
Main Logic Board