DESCRIPTION AND OPERATION
BLOCK DIAGRAM
2 - 2
I-E96-301B
®
Port RAM) with the current values of the inputs. The MFP can
read these values at any time, even if the IMASI03 is simulta-
neously writing to the dual port RAM.
Figure
shows a block diagram of the complete IMASI03
module.
Isolation Amplifier
Each of the 16 user-configurable input channels on the
IMASI03 consists of an isolation amplifier which is shown
in the slave block diagram, (Figure
). This isolation ampli-
fier contains:
•
Filtering stage.
•
Low drift channel voltage reference.
•
Programmable gain amplifier.
•
Signal isolation barrier.
•
Open input detection circuitry.
Input Multiplexer (MUX)
Once amplified, isolated, buffered and scaled, the input signal
is ready to be digitized. All the inputs, including the references
and cold junction input, are multiplexed through the same
analog to digital converter, as shown in Figure
.
Analog to Digital Conversion
Each input is multiplexed to the charge balanced analog to dig-
ital converter which converts the analog inputs to digital sig-
nals for the MFP. The A/D is software programmable for 16 to
24 bit resolution.
Figure 2-1. IMASI03 Functional Block Diagram
ISOLATION
AMPLIFIER 1
MULTI-
PLEXER
PROGRAMMABLE
A/D CONVERTER
PROM
SRAM
NVRAM
DUAL PORT
RAM
MEMORY
NONVOLATILE
RAM
DPRAM
MICRO-
CONTROLLER
LED
INDICATOR
8-POSITION
DIPSWITCH SW1
COLD JUNCTION
REFERENCE INPUT
ISOLATION
AMPLIFIER 2
ISOLATION
AMPLIFIER 3
ISOLATION
AMPLIFIER 16
P3 CONNECTOR
ON IMASI03
INPUTS FROM
TERMINATION
DEVICE
SLAVE
EXPANDER
BUS
INTERFACE
P2
CONNECTOR
ON IMASI03
TO/FROM
MFP
MASTER
TP35252A
SLAVE
EXPANDER
BUS
