Samsung SRP-350PG - SRP 350 B/W Direct Thermal Printer Service Manual page 56

7-4 RS-232C Communication Block Diagram
CPU
M30624FPFG
TRANSMIT (PRINTER)
DTR()
PC(HOST)
RXD(
)
RECEIVE (PRINTER)
DSR(
)
PC(HOST)
TXD()
Samsung Electro-Mechanics
TXD,RXD,DTR.DSR
Figure 7-7 RS-232C Communication Block Diagram
HOST BUSY HOST NOT BUSY
PRT transmits a data
PRT BUSY
PRT NOT BUSY
HOST transmits a data
HOST checks whether the Printer is BUSY.
Figure 7-8 RS-232C Communication Waveform
   




MAX232
DRIVER





 



         
         
HOST BUSY
Printer checks whether the host is BUSY.
PRT BUSY
7 Special Circuit Description
D-SUB25
FEMALE
DSR
PRINTER
TXD
DTR
PRINTER
RXD
7-5