2-10
Functional Description
Burst mode can also be used for pseudo-simultaneous
sample-and-hold (SSH) in conjunction with DMA or interrupt
operations.
Figure 2-2 shows the timing relationships of the paced and burst modes
for a queue of channel 4 to channel 7.
Figure 2-2. Timing of Conversion Modes for a Queue of Channels 4 to 7
Clock Sources
DAS-1800HC Series boards provide two clocks: a pacer clock and a burst
mode conversion clock. In paced mode, the pacer clock works alone to
time interrupt-mode and DMA-mode operations, as shown in Figure 2-2.
In burst mode and burst mode with SSH, the pacer clock and the burst
mode conversion clock work together to time interrupt-mode and
DMA-mode operations, as shown in Figure 2-2. These clock sources are
described in the following subsections.
Pacer Clock
Paced Mode Conversions
Burst Mode Conversions
Burst Mode Conversions
(with SSH)
Burst Clock
CH4
CH5
CH4 CH5 CH6 CH7
CH4 CH5 CH6
CH7
CH7
CH6
CH5
CH4
Hold
CH7
CH6
CH5
CH4
Hold
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