Service manual

Rev. 2.00
- 44 -
SRP-275
3-5-1(c) Cable Connection
(F.G) 1
(TXD) 2
(RXD) 3
(RTS) 4
(CTS) 5
(DSR) 6
(S.G) 7
(DTR) 20
1 (F.G)
2 (RXD)
3 (TXD)
4 (DTR)
5 (S.G)
6 (DSR)
7 (RTS)
8 (CTS)
PRINTER
SIDE
(25Pin)
HOST
SIDE
(9Pin)
3-5-1(d) Signal Description
Pin No. Signal name Signal direction Function
Body Frame GND - Frame ground
2 TXD Output Transmit data
3 RXD Input Receive data
6 DSR Input
This signal indicates whether the host computer can receive
data. (H/W flow control)
MARK(Logic 1) : The host can not receive a data.①
SPACE(Logic 0) : The host can receive a da② ta.
The printer transmits a data to the host, after confirming ③
this signal.
When XON/XOFF flow control is selected, the printer ④
does not check this signal.
7 Signal GND - Signal ground
20 DTR Output
This signal indicates whether the printer is busy.
(H/W flow control)
MARK(Logic 1) : The printer is busy.①
SPACE(Logic 0) : The printer is not busy.②
The host transmits a data to the printer, after confirming ③
this signal.
When XON/XOFF flow control is selected, the host does ④
not check this signal.
3-5-1(e) H/W Flow Control
When DTR/DSR flow control is select, before transmitting a data, the Printer checks whether the host is
BUSY or not. If the host is BUSY, the Printer does not transmit a data to the host. If the host is not BUSY, the
Printer transmits a data to the Host. The host is the same.
3-5-1(f) S/W Flow Control
When XON/XOFF flow control is selected, the printer transmits XON(ASCII 11h) or XOFF(ASCII 13h) signal
through the TXD line. If the printer is busy, the printer transmits XOFF(ASCII 13h) to host through the TXD
line. Then the host recognize that the printer is busy. So, the host does not transmit a data to the printer. If
printer is released from busy, the printer transmits XON(ASCII 11h) to host through the TXD line. Then the
host recognize that the printer is not busy. And the host transmit a data to the printer.