I/O Block
WBPEEUI240751C0 3 - 9
its operating voltages. Each 24 VDC input is fused and moni-
tored. Figure 3-8 details the block power section.
Logic Power
Redundant 24 VDC block logic power (BLP) is bussed through
the mounting column to the I/O module. The redundant BLP
power is auctioneered through summing diodes into a single
24 VDC. Onboard DC-to-DC converters develop +5 VDC,
+15 VDC, and –15 VDC operating voltages from the integrated
24 VDC.
The I/O module tests itself for a +5 VDC out-of-range condi-
tion. When this voltage is outside its normal operating range, a
hardware fault (i.e., power on reset) will occur and the block
operation will halt.
Power Monitor
The power monitor circuits test and report the status of the
redundant 24 VDC BLP inputs. The inputs are only tested for
Figure 3-7. Block Diagram - I/O Module
MEMORY
I/O C HA N NE L
IN T E R FA C E
MACHINE
FAU LT T I M E R
CPU
SP ECIAL
OPERATIONS
SW ITCH (SW 2)
HNET
IN T E R FACE
LED
DRIVERS
I/O
CHA NNEL 1
I/O
CHANNEL N
STATUS
LEDS
SE RIAL LINK
IN T E R FACE
I/ O SECT IO N
I/O CH A NN E L B U S
DATA BUS
BLO CK
POW ER
+5 VDC
A
B
B
B
A
A
+15 VDC -15 VDC
REDUNDANCY
LINK
OR
STATION LIN K
IFP
LFP
+24 VDC BLP
HNET
FIELD POWER
SELE CT
T00559A
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