Epson Apex-80 - Manual (Page 142)

Table F-2. Printing enabled/disabled signals and control conditions
On Line
(Indicator on)
SLCT IN
DC1/DC3
(Data on/off contr.)
ERROR BUSY ACKNLG
ON LINE
LOW DC1 /DC3
(S
W
. 2-1/interface) (no effect)
HIGH HIGH/LOW PULSED EA. CHAR.
ON LINE HIGH DC1 RECV’D HIGH HIGH/LOW PULSED EA. CHAR
ON LINE HIGH DC3 RECV’D HIGH HIGH/LOW PULSED EA. CHAR.
OFF LINE
HIGH/LOW DC1/DC3
(no effect) (no effect)
LOW HIGH NOT GENERATED
Printing
(Disabled/enabled)
ENABLED
(normal cond.)
ENABLED
*DISABLED
DISABLED
*Even though printing is disabled, data characters are received and acknowledged, since the printer is looking for another DC1 character,
which would allow it to resume printing.