Control Signals; Clock; Data; Aut - Philips PM2517E Service Manual

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I
I
I
E x p l a n a t i o n o f s t a t e s
I
J
W A I T |
= F i x e d w a i t i n g , 9 6 c l o c k p u l s e s .
I
The time is used for input settling
I
W n t f Z
= V a r i a b l e w a i t i n g t i m e . T h e t i m i n g o f t h e i n p u t s i g n a l h a s t o m e e t a c e r t a i n c o n d i t i o n
b e f o r e a m e a s u r e m e n t i s s t a r t e d . ( l M a x . 1 0 c l o c k p u l s e s ) .
_ t .
I
l s t a n d 2 n d = 1 2 2 8 8 c l o c k p u l s e s d e t e r m i n e d
b y t h e t i m e r
J
f u l E A S U R I N G
_
P E R r O D
I
J
SfOp
= End of the measurement, reset U/D counter
R A N G I N G
= l v l a n u a l o r a u t o m a t i c r a n g i n g c o m m a n d
I
coNlt\rAND
J
R A N G I N G
= S e l e c t i n g t h e c o r r e c t m e a s u r i n g r a n g e .
I
J
3.3.4.3. Control signals (Fig. 54 and 22)
Clock
T h e c l o c k s i g n a l ( 8 0 H z . . . 1 2 0 k H z ) d e t e r m i n e s t h e t i m i n g i n t h e i n s t r u m e n t a n d i s c o u n t e d b y a - 1 2 8 8 8
t i m e r . T h e o u t p u t o f t h e t i m e r i s s u p p l i e d t o t h e c o n t r o l l o g i c . O n t h i s s i g n a l t h e c o n t r o l l o g i c w i l l t a k e a c t i o n
v i z : s w i t c h i n g o f t h e s i g n a l A Z , A Z b y w h i c h t h e i n p u t o f t h e A D C i s s w i t c h e d ( r e f e r t o A D C 3 . 3 . 3 . ) .
Data
T h e d u t y c y c l e o f t h e d a t a s i g n a l i s d e p e n d e n t t o t h e h e i g h t o f t h e i n p u t v o l t a g e s u p p l i e d t o t h e P M 2 5 1 7
( r e f e r t o A D C 3 . 3 . 3 . ) . T h e d a t a s i g n a l i s s u p p l i e d v i a t h e U P / D O W N c o n t r o l t o t h e U P / D O W N c o u n t e r . T h e
UP/DOWN counter is counting the clock F,ulses. Data signal logic 1 is count up, loqic 0 is count down.
D u r i n g t h e 2 n d m e a s u r i n g p e r i o d t h e D A T A s i g n a l i s i n v e r t e d i n s i d e t h e O O 0 0 5 9 U P / D O W N N / A .
. l n c a s e o f m a n u a l r a n g i n g U P o r D O W N p u l s e s f r o m t h e U P / D O W N c i r c u i t a r e s u p p l i e d t o t h e O O 0 0 5 9 . l n t h e
ranging counter the pulses are converted into the range code I x depress is one range up or down. In the ranges
V . . . and V \ the number of ranges is four. BV means of signal ,f) this is extended to six.
Aut
B y m e a n s o f a l o g i c 1 o t s i g n a l A U T ( a u t o r a n g i n g ) , w h i c h i s g e n e r a t e d b y t h e U P / D O W N / A U T c i r c u i t , t h e d i g i t a l
section is switched to auto ranging mode. When the result of the UP/DOWN counter is larger than 10.000 in a
range {V-_
, V- or k() ) then the control logic switched automatically to a higher range. This is repeated
untill the contents of the counter is less than 10.000.
The same happens during down ranging is the automode the down level for the UP/DOWN counter is 900.
D o w n r a n g i n g i s r e p e a t u n t i l l t h e c o n t e n t s o f t h e c o u n t e r i s l a r g e r t h a n 9 0 0 .
Up/down/aut ranging circuit
For automatic or manual ranging the following conditions have to be met:
D e p e n d e n t t o t h e f u n c t i o n s e l e c t e d , a s p e c i f i e d r a n q e b l o c k i s a v a i l a b l e ( V : - ; : V \ , = 4 r a n g e s , O = 6 r a n g e s
UP or DOWN pulses have no effect when the lowest or highest range is met in the specified range block. (Reler
to specification of the OO 0059, chapter 3.4.4.).
T h e r a n g i n g c i r c u i t c o n s i s t s o f a s w i t c h i n g p a r t s i t u a t e d o n N 1 a n d a n i n d i c a t i o n p a r t s i t u a t e d o n t h e d i s p l a y
u n i t N 2 .
Fis.24.
5 T 2 5 t 6