Chapter 3 Functional Details; Pci-Das4020/12 Block Diagram; Analog Input Signal Path - Measurement Computing PCI-DAS4020/12 User Manual

Functional Details

PCI-DAS4020/12 block diagram

PCI-DAS4020/12 functions are illustrated in the block diagram shown here.
Four analog input channels per board
BNC
50 Ohm
S
External Pacer
TRIG1, TRIG2,
or GATE
BNC
Analog
Dual12-bit
Outputs
DAC
Digital I/0
24 I/O
(82C55)

Analog input signal path

Four single-ended analog input channels, connect from BNC connectors to individual amplifiers and then
connect to dedicated ADC's. Each path allows for:

50 ohm or high-Z termination, selected by solder gap

±1 V or ±5 V bipolar ranges, software-selectable (refer to the table below)

Auto-calibration for offset and gain adjustments for each channel and each range
Full Scale Input Range
+5 V to -5 V
+1 V to -1 V
Attenuator/
Amplifier
Input
MUX
Gain & Offset
AUTOCAL
Analog
Clock/
Trigger
PCI Bus Connector
(5V, 32 BIT, 33 MHZ)
Figure 8. PCI-DAS4020/12 functional block diagram
Local Bus
PC Bus
Controller
Input range
Attenuation
5
1
17
Chapter 3
ADC
Four
Channels
IN
VREF
CONV
12
System
Timing
Controller
Dual
32K x 24
SRAM
Divider Output
±1 V
±1 V