Measurement Computing DaqScan 2000 Series - Manual (Page 54)

8-4 Taking Measurements 898095 DaqScan/2000 Series
Channel Sampling Interval
In regard to analog input, DaqScan/2001 and DaqScan/2005 allow for programmable
sampling intervals of 5 us, 10 us, or 1000 us on a per channel basis. This mode allows some
DBK expansion channels [that change slowly for a higher degree of accuracy] to be sampled at
a longer interval, and channels that change more rapidly to be sampled at a shorter interval.
Each 5 µs, 10 µs, or 1000 µs interval reduces the maximum aggregate acquisition rate for the
entire scan by that amount.
Digital I/O Channels
There are 40 Digital I/O channels available to DaqScan/2000 Series devices. The channels are
grouped as follows:
8 Channels, A0 through A7 from P2 Port A
8 Channels, B0 through B7 from P2 Port B
8 Channels, C0 through C7 from P2 Port C
16 Channels, Digital 0 through Digital 15 from P3
The devices allow for either synchronous scanning of digital input channels or asynchronous
I/O operations for all configured digital channels.
Counter Input Channels
Counter 0, 1, 2, 3 (CTR0, CTR1, CTR2, CTR3)
DaqScan/2000 Series devices allow synchronous scanning of four16-bit counter input
channels. The 4 channels can be cascaded into two 32-bit counter channels. For either
cascaded or non-cascaded counter channels each channel can be configured for:
• Pulse Counting Mode – specifies that each counter should be cleared upon being
read and placed into the input scan.
• Totalize Counting Mode – specifies that each counter is to free-run and not be
cleared during the input acquisition.
Synchronous Input Acquisition Clocking
A /I Clock
DaqScan/2000 Series devices allow clocking of the synchronized inputs either by an internal,
programmable pacer clock or by external clocking. These products use a sequencer to
implement a multiplexing approach to gathering the input data. This means that with either
internal or external clocking the entire channel scan (including the sampling time for each
channel) may not exceed the maximum aggregate rate of 200 kHz.
Synchronous Output Operations
DaqScan/2001 and DaqScan/2004 allow synchronous output of any available D/A channels
at up to 100 kHz for each channel. All D/A channels may have output clocked out
synchronously.
Output Channel Configuration
Analog Output Channels (DaqScan/2001 and DaqScan/2004 only)
Each of the four D/A channels for DaqScan/2001 and DaqScan/2004 can be configured for
waveform output individually. If the D/A channel is not configured for waveform output it
then is available for asynchronous output operations.
Synchronous Output Clocking (DaqScan/2001 and DaqScan/2004 only)
A / O Clock
DaqScan/2001 and DaqScan/2004 allow clocking of the synchronized output by the acquisition
clock source, an internal, programmable pacer clock or by an external clock source. When the
clock source generates a new clock signal all outputs are updated concurrently. Regardless of
the clock source, the clock may not exceed the maximum update rate of 100 kHz.