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The DOB outputs pulses that correspond to the five digital nibbles (1234512345...12345
etc.). This sequence is repeated 20 times (100 samples/5 data elements) to the DIG OUT
channel. The diagram below shows a portion of this output for the first five data
elements.
Triggering and Thresholds
Two types of triggering thresholds can be set in the CBL 2:
Hardware triggering is set to trigger on a specific voltage level established by the
trigger threshold parameter.
Software triggering is set to begin data collection on either the rising edge or
falling edge of the signal, depending on the trigger type and trigger threshold
selected.
The THRESHOLD parameter specified in Command 3 can be used for two purposes:
If the operation in Command 1 is frequency, period, or count (operation = 5, 6, or 7
on Channel 1 only), then the threshold parameter in Command 3 sets a voltage
level in the CBL 2 hardware. The signal on the Vin pin of CH 1 must pass through
this voltage for the CBL 2 to see the signal change states.
If the operation in Command 1 is anything other than 5, 6, or 7, then the threshold
parameter in Command 3 specifies a trigger level and is measured in the units of
the sensor selected.
When triggering, sampling does not start until the signal on the trigger channel (also
specified in Command 3) passes through this level once in the direction specified. This
comparison of trigger level and signal level occurs in software, so any level in the
proper range can be selected. Also, either the Vin or VinLow pin (on any of the analog
channels or the sonic channel) can be used as the trigger channel. CBL 2 knows
whether to use the Vin or VinLow pin by looking at which operation was set up in
Command 1.
18
Sample
Clock
D3
D2
D1
D0
1
2
3
Figure 1. Digital Output Example
4
1
5
CBL 2 Technical Reference
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