Parallel centronics interface, Interface characteristics, A-8 2. parallel centronics interface – Output Solutions C I - 8 0 6 0 User Manual

Page 130

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Appendix A System Interface Description

A-8

2.

Parallel Centronics Interface

®

2.1

Interface Characteristics - Connector Pin Assignment / Signal
Definition

Signal Description

Pin No. Return line Direction

Pin No.

_______

Control Signal from the Host. Printer reads data line

1

19

Input

STROBE

(Data 1 to Data 8) when going low.

*)

Data 1 - 8

Data lines transfer the characters from the host to

2 - 9

20 - 27

Input

the printer. Data 8 = most significant bit.

_____

Acknowledge - Negative going pulse from the printer 10

28

Output

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 11

29

Output

that the printer is unable to receive any more data.

**)

PE

Paper Empty - Control signal from the printer. This

12

--

Output

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 13

--

Output

that the printer is ON-LINE and ready.

LG

Logic Ground

14

--

--

not used

15

--

LG

Logic Ground

16

--

CG

Chassis Ground

17

--

VCC

+ 5 volt

18

--

SG

Signal Ground

19 - 20 --

____

Control signal from the host. Does not reset the prin- 31

--

Input

INIT

ter.

*)

______

Control signal from the printer. A low level indicates

32

--

Output

FAULT

that the printer has been switched off, or the serial

*)

interface is active.

LG

Logic Ground

33

--

--

not used

34 - 35 --

_________

Compatible mode (low) 1284 nibble mode (high)

36

30

Input

SELECT IN

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), or
BUSY remains active until the printer enters the online state again.

IEEE Std 1284 Nibble mode including Device ID are supported.
The maximum throughput for data transfer is 42,000 characters per second.

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