Parallel Centronics Interface - Epson C I - 4 0 4 User Manual

Appendix A System Interface Description

2. Parallel Centronics Interface

2.1 Interface Characteristics - Connector Pin Assignment / Signal
Definition
_______ Control Signal from the Host. Printer reads data line
*)
STROBE (Data 1 to Data 8) when going low.
Data 1 - 8 Data lines transfer the characters from the host to
the printer. Data 8 = most significant bit.
_____ Acknowledge - Negative going pulse from the printer
*)
ACKN indicates that the printer has received a character
and is ready for the next data transfer.
BUSY Control signal from the printer. A high level indicates
that the printer is unable to receive any more data.
PE Paper Empty - Control signal from the printer. This
signal goes high when paper runs out, i.e. load
upper or lower tractor, paper jam.
SELECT Control signal from the printer. A high level indicates
that the printer is ON-LINE and ready.
LG Logic Ground
-- not used
LG Logic Ground
CG Chassis Ground
VCC + 5 volt
SG Signal Ground
____ Control signal from the host. Does not reset the prin-
*)
INIT ter.
______ Control signal from the printer. A low level indicates
*)
FAULT that the printer has been switched off, or the serial
interface is active.
LG Logic Ground
-- not used
*)
Overlined signal names indicate that the signal is true when the signal level is
low.
**)
When the interface buffer is full except for the last character, BUSY will not be
reset. BUSY will be reset when buffer space is available again for least 512
characters in the interface buffer. While the printer is offline (Stop Mode)
BUSY remains active until the printer enters the online state again.
A-8
®
Signal Description
Pin No. Return line Direction
Pin No.
1 19
2 - 9 20 - 27
10 28
11 29
**)
12 --
13 --
14 --
15 --
16 --
17 --
18 --
19 - 20 --
31 --
32 --
33 --
34 - 35 --
Input
Input
Output
Output
Output
Output
Input
Output