HP 7470A Interfacing And Programming Manual page 109

Oo eration
While o p e r a t i n g in t h i s e n v i r o n m e n t , the plotter m a y b e in one of three
states: on-line, programmed-off; on-line, programmed-on; or monitor
mode.
O n - L i n e , P r o g r a m m e d - O f f S t a t e
T h e plotter c a n only be in t h i s s t a t e if t h e Y/D switch o n t h e r e a r p a n e l
is set to Y (used w i t h Y-cable). W h e n this switch is set to Y, t h e plotter is
placed i n t h e on-line, p r o g r a m m e d - o f f s t a t e by e i t h e r t u r n i n g t h e
plotter's LINE switch to ON or by receipt of a plotter off instruction from
t h e computer or of a t e r m i n a l - g e n e r a t e d Break s i g n a l while t h e plotter
is in t h e on-line, p r o g r a m m e d - o n state. I n t h e on-line, programmed-off
state, t h e plotter's processor p a s s e s d a t a between t h e c o m p u t e r a n d t h e
t e r m i n a l a s s h o w n i n t h e following d i a g r a m . T h e plotter will respond
only to a plotter o n instruction from t h e h o s t computer.
TERMINAL
COMPUTER
1 — *
HI
as
,
Y-CABLE
CONNECTOR
If
1H
F
iH
s
■MM t
ROCESSOR
CANS FOR
PLOTTER ON'
NSTRUCTION
PLOTTER
Plotter in On-Line, Programmed-Off State
io-6 RS-232-C/CCITT V.24 INTERFACING
O n - L i n e , P r o g r a m m e d - O n S t a t e
When t h e rear-panel switch labeled Y/D is set to D, t h e plotter is placed
in t h e on-line, p r o g r a m m e d - o n s t a t e by t u r n i n g on t h e plotter. W h e n t h e
Y / D s w i t c h is s e t t o Y, t h e p l o t t e r is s w i t c h e d f r o m t h e o n - l i n e ,
programmed-off s t a t e to t h e on-line, p r o g r a m m e d - o n s t a t e w h e n a
plotter on instruction, E S C . ( or E S C . Y, is received from t h e computer.
W h e n in this state, t h e plotter operates i n r e s p o n s e to i n s t r u c t i o n s
received from t h e c o m p u t e r a s s h o w n in t h e following figure. W h e n t h e
plotter instructions request output, it is provided a s s h o w n . T h e commu­
n i c a t i o n c h a n n e l from t h e t e r m i n a l to t h e c o m p u t e r , t h r o u g h t h e
plotter, is m a i n t a i n e d to provide operator e n t r y into t h e computer.
T h e plotter's processor m o n i t o r s t h e c h a n n e l from t h e t e r m i n a l to t h e
computer for a t e r m i n a l - g e n e r a t e d B r e a k s i g n a l . T h e p l o t t e r will inter­
pret a n y t h i n g g r e a t e r t h a n a 130-millisecond s p a c e a s a Break. T h i s
B r e a k s i g n a l is r e t r a n s m i t t e d t o t h e c o m p u t e r a n d in-process plotter
o u t p u t s are aborted, b u t p l o t t i n g c o n t i n u e s until s t o r e d buffer d a t a is
completed. A n e w plotter o n i n s t r u c t i o n from t h e c o m p u t e r i s required
to r e s u m e plotting o p e r a t i o n s . T h e plotter will i g n o r e a B r e a k s i g n a l if
t h e Y/D switch is set to D.
It s h o u l d be noted t h a t i n t h e on-line, p r o g r a m m e d - o n s t a t e (but n o t in
m o n i t o r mode w h i c h is described in t h e n e x t p a r a g r a p h ) all d a t a
g e n e r a t e d by t h e t e r m i n a l a r e routed t h r o u g h to t h e c o m p u t e r on a
noninterference b a s i s w h e n t h e plotter is n o t d o i n g o u t p u t s . D a t a
g e n e r a t e d by t h e t e r m i n a l a r e ignored while o u t p u t is o c c u r r i n g . How­
ever, all d a t a g e n e r a t e d b y t h e c o m p u t e r a r e intercepted b y t h e plotter
a n d n o t p a s s e d to t h e t e r m i n a l .
COMPUTER
OUTPUTS \
, , PROCESSOR
PLOTTER SCANS FOR
INSTRUCTIONS " B R E A K "
Plotter in On-Line, Programmed-On State
RS-232-C/CCITT V.24 INTERFACING 10-7