Epson U375 - TM B/W Dot-matrix Printer, Technical Manual

Page: 26 / 179

1-11
Table 1-7. Interface Connector Specifications and
Functions (continued)
Pin Signal
Number Name
2) When XON/XOFF control is
selected, the signal indicates
whether the printer is correctly
connected and is ready to re-
ceive data.
SPACE indicates "ready". The
signal is always SPACE ex-
cept in the following two
cases:
• During the interval from
power-on until the printer is
ready to receive data.
• During the self-test.
25 INIT I Changing the DIP switch setting
enables this signal to be used as
a reset signal for the printer.
The printer is reset when the
signal remains SPACE for 1 ms
or more.
(
✽
1) The “buffer full” condition in this case starts when
remaining buffer space falls to 10 bytes or less and
ends when it becomes 20 bytes or more.
The printer ignores the data when the remaining
space in the receive buffer is 0 bytes.
Note
Pins 8 - 19 and 21 - 24 are not used.
1.3.4 Interface
See Chapter 7 for the TM-U375P interface.
Data transfer principle: Serial (RS-232C interface)
Synchronization: Asynchronous
Handshake (
✽
): DTR/DSR or XON/XOFF
Signal level:
MARK: -3 to -15 V (logical “1”/OFF)
SPACE: +3 to +15 V (logical “0”/ON)
(Voltage measured at connector, referenced to SG)
Baud rate (
✽
): 1200, 2400, 4800, 9600 bps
Data length (
✽
): 7 or 8 bit
Parity (
✽
): None, even, odd
Number of stop bits: 1 or more (Stop bit at printer side
is fixed to “1”.)
Connector type: D-SUB 25 female or equivalent
(
✽
) Can be set with DIP switches on the bottom of the
printer (see Tables 1-9 and 1-10.)
Table 1-7. Interface Connector Specifications and
Functions
Pin Signal
Number Name
1 FG — Frame ground
2 TXD O Transmit data
3 RXD I Receive data
4 RTS O Same as DTR signal
6 DSR I Indicates whether the host is
ready to receive data. SPACE
indicates "ready," and MARK in-
dicates "not ready." If DTR/DSR
control is used, the printer checks
this signal before sending data
(except data sent by DLE EOT
and GS a). If XON/OFF control is
used, this signal is not checked.
This signal can be used to reset
the printer according to the DIP
switch settings. (Refer to Table
1-10.)
The printer is reset when the
signal is MARK with more than 1
ms pulse width.
7 SG — Signal ground
20 DTR O 1) When DTR/DSR control is se-
lected, this signal indicates
whether the printer is busy.
MARK indicates busy, and
SPACE indicates not busy.
The busy condition is changed
using DIP switch 3 on bank 2
as follows:
I/O Function
During the interval from power-
on (reset using the interface) until
the printer is ready to receive data.
During the self-test
When the cover is open.
During paper feeding with the
PAPER FEED button.
When printing has stopped due to
a paper-end.
When an error has occurred.
When the receive buffer becomes
full (
✽
1).
DIP SW 2-3 Status
ON OFF
BUSY BUSY
BUSY BUSY
— BUSY
— BUSY
— BUSY
— BUSY
BUSY BUSY
Printer Status
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Off line
Function I/O
CONFIDENTIAL