DESCRIPTION AND OPERATION
MODULE BLOCK DIAGRAM
2 - 2
I-E96-313A
®
The data selector block drives the output circuits and lights the
front panel output status LEDs. It uses data from the output
register or default register to do this. During normal operation,
it selects the output register data.
Output Control Logic
An output register holds the data that controls the outputs.
The slave expander bus interface writes master module data to
this register. This data, sent to the data selector, determines
the output states (ON or OFF).
Default data from the master module is sent to the default reg-
ister. The master module configuration sets the default values
(Function Code (FC) 128). The default register is reset to logic
zeros during power up to drive the outputs to a de-energized
state. FC 128 in the master module configuration selects the
output values used to drive the output circuits in the event of a
master module failure (
time-out
). If FC 128 is not defined, the
outputs will go to a de-energized state during a
time-out
. Refer
to the
in this section for further explana-
tion of
time-out.
Figure 2-1. Digital Slave Output Module Block Diagram
LOGIC
POWER
GROUP A
GROUP B
DIGITAL
OUTPUTS
SLAVE
EXPANDER
BUS
TP27132A
SLAVE
EXPANDER BUS
INTERFACE
BUS FAULT
DETECTOR
MODULE
STATUS
DATA
SELECTOR
STATUS
BUFFER
DEFAULT
CONTROL
LOGIC
OUTPUT
REGISTER
DEFAULT
REGISTER
P2
P3
P1
ADDRESS SWITCH
MODULE
STATUS LED
DIGITAL
OUTPUT
1
8
OPEN
S1
GROUP A
LEDs
GROUP B
LEDs
Figure 2-2. Digital Output Circuit
TP27136A
+5 V
FIELD
OUTPUT
–
+
FROM
OUTPUT
CIRCUITRY
