Star Micronics NP-225 - Manual (Page 13)

10
3. Interface specifications
3.1 Parallel interface (Centronics)
1) Data input
: 8 bit parallel method(DATA 0 – DATA 7)
2) Control signals : /ACK, BUSY, /STB, /ERROR, PE, SLCT, /INIT
3) Input signal to a printer
DATA 0 – 7 : 8 bit parallel signal(positive logic)
/STB : Signal to read 8 bit data(negative logic)
/INIT : Signal to reset an entire printer(negative logic)
/LF : Signal to feed paper to print mechanism(negative logic)
4) Output signal from a printer
/ACK : Enquiry signal for 8 bit data. It’s also pulse signal which is output after
BUSY signals (negative logic)
BUSY : Indicate BUSY status of the printer. Inputs new data at LOW status
(positive logic)
/ERROR : This signal becomes LOW when a printer is in the alarm status.
In the LOW status, all control circuits in the printer stops (negative logic)
PE : Outputs when roll paper becomes empty (positive logic)
SLCT : Signal to indicate on-line status (positive logic)
5) Input/Output signal level
Standard value
Code
Min. TYP. Max.
Unit
Input low level V
IL
- - 0.18Vcc V
Input high level V IH 0.7Vcc - - V
Output low level V OL - - 0.7Vcc V
Output high level V OH 0.7Vcc - - V
*I
OL
4mA
6) Input/Output conditions
VCC
10K
LF
IN PUT
VCC
VCC
74LV574
STROB
PD0~PD7
ACK, P E, SLCT, ERROR
BUSY
INIT IN
OUT PUT
OUT PUT
IN PUT
IN PUT
IN PUT
3.3K
100
470p
3.3k
3.3K
74LV14
74LV14
47
74LV32
47
1SS319
510