PCI-DAS6030 & PCI-DAS6032 User's Guide
Functional Details
22
t
w
t
w
=23 ns minimum
t
p
t
w
t
p
=50 ns minimum
Figure 16. A/D EXTERNAL TIME BASE signal timing
A/D STOP signal
The A/D STOP signal indicates a completed acquisition sequence. You can program this signal to be available
at any of the AUXOUT pins. The A/D STOP output signal is a 50 ns wide pulse whose leading edge indicates a
DAQ done condition. Figure 17 shows the timing for the A/D STOP signal.
t
w
t
w
= 50 ns
Figure 17. A/D STOP signal timing
ATRIG signal
In addition to standard digital trigger features, the PCI-DAS6030 and PCI-DAS6032 also provide analog
triggering capability. When using the analog trigger, acquisitions may be started and controlled via an analog
signal. There are four trigger/gate modes available using the analog trigger feature:
Trigger – positive or negative slope.
Gate – above reference or below reference.
Hysteresis – positive or negative hysteresis.
Window – inside or outside window.
The Trigger mode is used to start an acquisition sequence. The remaining modes provide gating functions
during an acquisition sequence which start and stop the acquisition based on the gate condition.
There are two possible inputs for the analog trigger source (see Figure 18). The first is the AUXIN0/ATRIG pin
on the 100-pin I/O connector. This is a software selectable dual-purpose pin that supports either digital or
analog trigger inputs. The source selection defaults to analog trigger on power-up and may be modified at any
time using
Insta
Cal. The input range on the ATRIG pin is always ±10 V. 12-bit DACs are used to set the HI and
LO levels for the threshold(s). The threshold resolution in this mode is 4.88 mV per step.
Caution!
Remove all analog inputs before configuring this pin as a digital input. Any voltage levels above
±15V in this configuration may cause damage to the product!
The second possible analog trigger source is the post-gain version of any one of the 16 analog inputs. In this
mode, the voltage present on the first channel in the scan may be used to initiate the acquisition sequence.
Since the input to the analog trigger circuit has been scaled by the selected range, the effective resolution of the
thresholds is equal to the A/D's full-scale-range (±2.5V) divided by 4096. For example, the ±2.5V range allows
for 5V/4096, or 1.2 mV of threshold resolution.
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