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Additional Information
After Power-ON DTR and RTS are activated and the printer is ready to receive
data.
XOFF is sent, when the interface buffer has only space left for 256 more charac-
ters. XOFF is sent again, at a level of 128 characters buffer space. Further
incoming data will be stored until the interface buffer is full. All data sent in
addition will get lost.
XON is sent when the interface buffer provides space for a minimum of 512
characters.
XON/XOFF can only be sent successfully when CTS and (DSR) is at active
state.
XOFF will be sent immediately if local mode is entered.
XON is sent again, if local mode is left and a minimum of 512 byte interface
buffer is available.
Appendix A System Interface Description
A-7
Appendix A System Interface Description
®
3 Parallel Centronics Interface
Interface Characteristics - Connector pin assignment / signal definition
Signal Description
_______
Control Signal from the Host.
*)
STROBE
Printer reads data line (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 - Control signal from the printer. Logi-
*)
ACKN
cal 0 indicates that the printer has received a print/-
control character and is ready for the next data
transfer.
BUSY
Control signal from the printer. Logical 1 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. Always logical 1.
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
*)
INIT
printer but generates an acknowledge pulse (logical
1).
______
Control signal from the printer. Always logical 1. If it
*)
FAULT
goes to logical 0 the printer has been switched off.
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 space is available again for least 256 charac-
ters in the interface buffer. While the printer is offline (Stop Mode) BUSY
remains active until the printer enters the online state again.
A-8
Pin No.
Return
Direction
line Pin
No.
1
19
Input
2 - 9
20 - 27
Input
10
28
Output
11
29
Output
12
--
Output
13
--
Output
14
--
15
--
16
--
17
--
18
--
19 - 30
--
31
--
Input
32
--
Output
33
--
34 - 36
--
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