I . I N T R O D U C T I O N
T h e D S - 2 0 0 0 i s a d u a l c h a n n e l a s y n c h r o n o u s s e r i a l
c o m m u n i c a t i o n a d a p t e r w h i c h u t i l i z e s b a l a n c e d
d i f f e r e n t i a l d r i v e r s a n d r e c e i v e r s t o p r o v i d e R S - 4 2 2 - A
c o m m u n i c a t i o n s . I t i s c a p a b l e o f r e l i a b l e c o m m u n i c a t i o n s
o v e r l o n g d i s t a n c e s ( 4 0 0 0 f e e t ) w i t h i n n o i s y i n d u s t r i a l
e n v i r o n m e n t . D a t a i s c o m m u n i c a t e d t h r o u g h t w o D - 9
c o n n e c t o r s w h i c h p r o v i d e s h i e l d i n g f r o m e n v i r o n m e n t a l
n o i s e . O p t i o n a l h i g h s p e e d t r a n s i e n t s u p p r e s s e r s m a y
a l s o b e i n s t a l l e d o n t h e D S - 2 0 0 0 t o f u r t h e r r e d u c e t h e
effects of environmental signal transients and surges.
The serial interface is accomplished through a pair
o f 1 6 5 5 0 A s y n c h r o n o u s C o m m u n i c a t i o n E l e m e n t s ( A C E s ) . T h e
1 6 5 5 0 i s c o m p a t i b l e w i t h t h e 8 2 5 0 a n d 1 6 4 5 0 A C E s u s e d i n
t h e I B M P C / X T / A T m o d e l s . T h e 1 6 5 5 0 a l s o h a s a n
a d d i t i o n a l F I F O m o d e t h a t r e d u c e s C P U o v e r h e a d a t h i g h e r
data rates.
The DS-2000 supports sixteen base addresses for each
A C E t h r o u g h t h e P r o g r a m m a b l e O p t i o n S e l e c t ( P O S )
i n c l u d i n g t h e e i g h t a d d r e s s e s d e s i g n a t e d S E R I A L 1 t h r o u g h
S E R I A L 8 . T h e a d d r e s s e s a r e i n d e p e n d e n t f o r e a c h
c h a n n e l . C P U i n t e r r u p t l e v e l s e l e c t i o n s a r e a l s o h a n d l e d
t h r o u g h t h e P O S . E a c h c h a n n e l m a y s e l e c t a s e p a r a t e
interrupt or share an interrupt level with other devices.
I I . B O A R D D E S C R I P T I O N
A c o m p o n e n t d i a g r a m o f t h e D S - 2 0 0 0 s h o w i n g t h e
l o c a t i o n s o f t h e 1 6 5 5 0 A C E s , c o n f i g u r a t i o n j u m p e r s , a n d
D - 9 c o n n e c t o r s i s s h o w n i n f i g u r e 1 . T h e f i r s t
c o m m u n i c a t i o n c h a n n e l i s c o n t r o l l e d b y t h e 1 6 5 5 0 l a b e l e d
U 9 , j u m p e r J 2 , a n d i s a c c e s s e d t h r o u g h t h e c o n n e c t o r
l a b e l e d C N 1 . T h e s e c o n d c h a n n e l u s e s t h e 1 6 5 5 0 l a b e l e d
U 1 0 , j u m p e r J 3 , a n d i s a c c e s s e d t h r o u g h t h e c o n n e c t o r
labeled CN2. The clock rate divider for both channels is
controlled by jumper J1.
iii
