2-2
Functional Description
Figure 2-1. DAS-8 Series Functional Block Diagram
Analog Input Features
DAS-8 Series boards use a 12-bit, successive approximation
analog-to-digital converter (ADC) with integral sample and hold. The
ADC provides 12-bit resolution ±1 least significant bit (LSB), providing
an effective accuracy of 11 bits. The ADC converts one sample every
25
µ
s (25
µ
s max.), providing an average conversion frequency of more
than 4 kHz (machine and software dependent).
IBM PC AT Bus
Interrupt Select
Levels 2-7
(Jumper)
Address
Decode &
Bus Interface
Bus Power for
Expansion & Interface
+5V
+12V
-12V
COM
Status
Registers
Control
Registers
Interrupt
Control
I/O
Buffers
IP1
IP2
IP3
OP1
OP2
OP3
OP4
Digital I/O
Channel Select
& Scan Logic
Gain Control
DAS-8/PGA(G2)
MUX
Ch 0
Ch 7
Analog In
8 Channels
12 Bit A/D
with
Sample/Hold
Conversion
Control Logic
Internal Data Bus
Clock Generate
& Control Logic
Timer/
Counter
Clk 2
Gate 2
Out 2
Clk 1
Gate 1
Out 1
Clk 0
Gate 0
Out 0
Clk 1
Gate 1
Gate 2
Out 1
Out 2
Gate 0
Clk 0
Out 0
INT_IN
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