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REV.-A
2.3.2
I n t e r f a c e
This printer has both an 8-bit parallel interface and an RS-232C serial interface.
2.3.2.1 8-Bit Parallel Interface
Operating Principles
Figure 2-42 shows the 8-bit parallel interface data transmission timing. Data is transferred between
a host computer and the printer using the following sequence:
a)
b)
c)
d)
BUSY
/
$
DATA
,
STROBE
Figure 2-42. 8-Bit Parallel Data Transmission Timing
First, the host computer confirms that the BUSY signal from the printer is low or that the
signal from the printer is high. When the BUSY signal is low, the printer is ready to receive data.
When it is high, the printer can not receive data from the host computer since the printer is
data. Therefore, the host computer does not transfer data until the BUSY signal changes
from high to low. (Some host computers check both the BUSY and
signals, and others just
check either the BUSY or
signal.)
After the host computer has confirmed that the BUSY signal is low, it places data (8 bits per word)
in parallel on the data bus (DO - D7), and the printer reads the data
edge of the STROBE
pulse.
After receiving a data word from the host computer, the printer sets the BUSY signal high to inform
the host computer that the printer is
data and is not ready to receive any more data.
After
the data, the printer sets the
signal low, allowing the host computer to
transfer data again. The printer sets the BUSY signal low approximately 5
after setting the
signal low, then sets the
signal high after approximately 5
informing that the
host computer that the printer is ready to receive data.
2-48
Summary of Contents for LQ-2550
Page 1: ...L Q 2 5 5 0 TECHNICAL MANUAL EPSON ...
Page 240: ...REV A P r cl Figure 6 3 LQ 2550 Lubrication and Adhesive Application Points Diagram 2 6 3 ...
Page 241: ...REV A 7 i_ Figure 6 4 LQ 2550 Lubrication and Adhesive Application Points Diagram 3 6 4 ...
Page 252: ...REV A I 1 I 7 v m o m x b Figure A 6 PPD781OHG Block Diagram A 7 ...
Page 297: ...REV A 1 L I Irl N I i t 1 I I x Figure A 50 ROPSE Board Circuit Diagram A 52 ...