Fluke 8502A - Theory of Operation Overview; Block Diagram Description; Bus Structure Explanation

3-1.
INTRODUCTION
3-2. This section of the
manual describes the theory
of
operation for the 8502A
mainframe, which includes the
modules necessary for
DC Volts and DC Ratio
measure-
ments. Block Diagram
descriptions give an overview of the
operation of the
modules and an explanation of
the bus
structure.
Circuit Analyses give a
more detailed
description
of the circuitry.
Optional modules are
described in Sect. 6.
3-3.
BLOCK
DIAGRAM DESCRIPTION
3-4.
Bus Structure
3-5.
The
8502A
is constructed
with
a
bus archi-
tecture similar to a
computer. Figure
3-1
is an
overall block
diagram of the instrument with optional
modules drawn in
dashed lines.
Figure
3-2
is a
block diagram
illustrating signal
flow. A
microprocessor-based controller
module controls
information flow on the
three buses. The controller
sets up
each of the analog modules
for
a
measurement by address-
ing
the modules as memory locations. An
unguarded digi-
tal
interbus
is
used to connect the controller to the
front
panel and to digital
option modules such as the calibration
memory and a remote I/O
(input/output) interface.
3-6.
The unguarded
digital
bus consists of the followini
lines:
1 .
Address/Control (IC) lines
—7.
2.
Bidirectional
data (ID)
lines —8.
3..
Real time (RT) lines —7.
4.
Handshake lines (INT—interrupt,
ACK—acknow-
ledge,
INA—interrupt acknowledge).
5 . Power
Supply lines
.
3
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