Philips PM2517E Service Manual page 56

5 0
Description
Data input
Auto zero
lnverse of auto zero
Polarity
Data Hold
Overrange
B C D i n f o r m a t i o n
G R o u N D +
1 4
1 5
t o
1 1
A Z
DATA
P O L
O V F
Incoming data with a duty-cycle depending on the input voltage
of the ADC. During the second measuring period the DATA signal
is anverted,
Auto zero outputs are used for commutating the input voltage of
t h e V - l c o n v e r t o r f o r a u t o m a t i c z e r o c o m p e n s a t i o n .
The state of signal PO L is determined by the input voltage of the
Pl\4 2517, which is measured by the ADC.
L O G t C 0 = _ p o t a r i t y
L O G I C I = + p o l a r i t y
Logic 0 normal measuring.
Logic 1 the present value of the last completed measuring cycle
w i l l b e h e l d .
l f D H b e c o m e s 1 t h e m e a s u r i n g c y c l e w i l l b e e n d e d , t h e r e i s n o
transfer of measured data.
T h e c o n t r o l l o g i c w i l t b e w a i t i n g u n t i l D H b e c o m e s 0 , a n d a n e w
measuring cycle will be started.
When a measuring result is ) 9999 in the highest permisseable
r a n g e ( i n m a n u a l o r a u t o m a t i c r a n g i n g m o d e ) t h e n s i g n a l O V R
w i l l b e c o m e l o g i c l . S i g n a l O V R i s s u p p l i e d t o t h e d i s p l a y .
In case of overload only digit
'l02
and also the corresponding
decimal point is ignited.
BCD coded result.
B i t p a r a l l e l - w o r d
s e r i a l .
Together with the signals DS1 and DS2 (digit select) the correct
digits in the correct order can be made visible.
S u p p l y Z e r o . 0 V ü
20
2 1
2 3
24
A2
A 1
AO
G N D