I. INTRODUCTION
The
over long distances (4000 feet) within | noisy industrial |
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 |
noise . Optional | high speed transient suppressers may |
also be installed on the DS - 2000 to further reduce the | |
effects of environmental signal transients and surges. | |
The serial interface is | accomplished through a pair | ||||
of 16550 | Asynchronous Communication Elements (ACEs). The | ||||
16550 is | compatible with the | 8250 | and | 16450 ACEs used in | |
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 | ||||
additional FIFO mode that reduces | CPU | overhead | at higher | ||
data rates. |
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The | 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 )
including | the eight | addresses | designated SERIAL 1 through | |
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 | ||
channel. | CPU interrupt level | selections are also handled | ||
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. |
II. BOARD DESCRIPTION
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
locations of | the 16550 | ACEs, configuration | jumpers, and |
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 | ||
communication | channel is | controlled by the | 16550 labeled |
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 labeled CN1. The second channel uses the 16550 labeled U10, jumper J3, and is accessed through the connector labeled CN2. The clock rate divider for both channels is controlled by jumper J1.
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