Digital Input Module Circuitry - ABB Symphony Harmony Series Instruction

Logic Power
IN P U T C IR C U ITRY
A
D I+
A
1
A , C
A , B
JU M P E R
D I–
N OT E :
A = M O U N T E D O N IM D S I2 2
B = M O U N T E D O N IM D S I1 4
C = M O U N T E D O N IM D S I1 3
Figure 2-2. Digital Input Module Circuitry
the DSI module. This data is output by the buffer circuits (con-
trol logic) to the I/O expander bus interface (Fig. 2-1). The I/O
address in function code 84 must be the same as the address
set on address dipswitch (S1).
Point Data Byte
Point data is two eight-bit bytes. Each byte corresponds to
group A or group B inputs. Each bit of data represents one
input. The bit value reflects the state of that input, either open
(logic zero) or closed (logic one).
Status Byte
The status byte ensures module integrity. It makes sure I/O
expander bus communication and controller configuration are
correct. The controller reads the status byte and compares it
to an expected value. If a mismatch occurs, it flags the error
and marks the point as bad quality.
Logic Power
Logic power (+5 VDC) drives the DSI module circuits. It con-
nects through the 12-pin card edge connector (P1) shown in
Figure 2-1.
2 - 4
A , B
+ 5 V D C
JU M P E R
R E S IS TO R S
1
A
JU M P E R
IS O L ATIO N
T H R E S H O L D A N D
FILTE R IN G B LO C K
V R E F
+
–
+ 5 V D C
LE D
D IG ITA L
IN P U T
+ 5 V D C
V R E F
T 04 1 45 A
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