SYSTEM TECHNICAL MANUAL
HARDWARE DESCRIPTION
Figure 2.45 Centronics interface tim ing
STROBE/
Pulse is used to clock read data in. The pulse w idth must
be more than 1 Msec at receiving printer. Read in of data
is performed at the " lo w " level of this signal.
A C K N LG /
Indicates th at data has been received by the printer. New
data cannot be received before AC K N LG is reset. Pulse
w idth 2.5 Msec to 10 Msec.
BUSY
When " H IG H " the printer indicates that it cannot receive
data. The signal becomes "H IG H " in the fo llo w ing cases:
- During data entry (depending on printer)
- During printing operation
- In o ff-line state
- During printer error status
- During line feed
D A T A 1-8 Signals represent inform ation o f parallel data "H IG H " =
log 1; "L O W " = log 0.
PE "H IG H " signal indicates th at the printer is out of paper.
SLCT
(Input) Printer is in selected mode (option).
AU TO FEED/ (O utput) Auto line feed (option).
IN IT / (Output) Printer reset (optio n).
ER R O R/
(Input) Indicates printer error (option) fo r example at
paper end, off-line , safety switch open, failure status.
TEST 1-4 O ptional loop test inputs.
Figure 2.46 Centronics signals
2-65
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