Omega Engineering OMB-DBK-34A, User Manual

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4
2
Base Address set to 0001
Expansion Address set to 1111
Daq device System
or LogBook System
Sequencer
100 kHz
Clock
DBK card or module
JP1 channel
select jumper
2
MUX
4
0001
1111
MUX
P1 P1
CH15
CH1
CH1
ADC
PGA
PGA
Example Channel Selection
Signal Acquisition
Sequencer
The hardware sequencer performs several functions:
•
Allows each channel to have an independent gain.
•
Ensures that channels are scanned at exactly 10 µ s intervals.
•
Allows channels to be accessed randomly in the scan rather than “start channel to end channel”.
•
Provides high-speed access to expansion modules.
512-Step Random Access
Channel/Gain Sequencer
8 DE/16 SE
Analog Input
Multiplexer External
Multiplexer
Control Programmable
Gain Amplifier
×1, ×2, ×4, ×8
16 High-Speed
Digital Inputs
4 signals to be used as:
general purpose inputs
or
Sequencer Reset
Main Expanded
Ch
0
1
2
...
15
×1
×2
×8
...
×4
uni
uni
bi
...
bi bi
bi
...
uni
n/a ×60
×20
...
×40
n/a
16
17
...
271
272
Ch Ga Ga Set. Set.
Trigger
select
Analog input
from P1
Analog input
from P1
Trigger
input
Analog
trigger-in
comparator
Gain adjusted analog
input from P1
Computer output signal
through digital-to-analog
converters
Programmable
sequencer timebase,
10 s to 10 hours
µ
Signal from
PC (ISA)
Bus interface
100 kHz
clock
2 2 1
2
1
1
1 Aux. Counter Gate
1 TTL Trigger Input
2 Gain Select Outputs
(
) for expansion boards
Gain Adjust
Polarity setting: bipolar or unipolar
The LogBook or Daq device holds the scan information in its internal sequencer. On every timebase
“tick”, the sequencer steps through all the programmed channels and sets the gain for each channel (also
the unipolar/bipolar setting for the /2000 Series Devices). Thus, each sample in a scan is read optimally.
In addition to controlling the LogBook or the Daq device, the sequencer controls the programmable
features on expansion cards via the P1 connector.
This architecture ensures that the same 10 µ s sampling (5 µ s or 10 µ s for /2000 Series Devices) exists for
external channels as well as internal channels.
DBK Option Cards and Modules
886995
Signal Management 1-9