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