70
•
Technical Specifications
Xtium-CL PX4 User's Manual
Input Level
Switch Point
Propagation Delay
(rising edge signal
↑
)
Propagation Delay
(falling edge signal
↓
)
TTL/RS-422
1.6V
1.75
µ
s
5.5
µ
s
12V
6V
2.6
µ
s
2.6
µ
s
24V
12V
1.9
µ
s
3.1
µ
s
For External Trigger usage:
•
Input signal is “debounced” to ensure that no voltage glitch is detected as a valid transition.
This debounce circuit time constant can be programmed from 1
µ
s to 255
µ
s. Any pulse smaller
than the programmed value is blocked and therefore not seen by the board. If no debounce
value is specified (value of 0
µ
s), the minimum value of 1
µ
s will be used.
•
Refer to Sapera parameters:
CORACQ_PRM_EXT_TRIGGER_SOURCE
CORACQ_PRM_EXT_TRIGGER_ENABLE
CORACQ_PRM_EXT_TRIGGER_LEVEL
CORACQ_PRM_EXT_FRAME_TRIGGER_LEVEL
CORACQ_PRM_EXT_TRIGGER_DETECTION
CORACQ_PRM_EXT_TRIGGER_DURATION
•
See also *.cvi file entries:
External Trigger Level, External Frame Trigger Level, External Trigger Enable, External Trigger
Detection.
•
External Trigger Input 2 used for two pulse external trigger with variable frame length line scan
acquisition.
Trigger Signal Total Delay
Opto-Coupler
t(oc)
Debouncer
1..255 us
t(d)
External Trigger
t(et)
Validated Trigger
t(vt) = t(et) + t(oc) + t(d)
Figure 25: External Trigger Input Validation & Delay
Let
t(et) = time of external trigger in
µ
s
t(oc) = time opto-coupler takes to change state (time varies dependent on
input voltage)
t(d) = user set debounce duration from 1 to 255
µ
s
t(vt) = time of validated trigger in
µ
s
Table 31: External Trigger Timing Specifications
Note: Teledyne DALSA recommends using the fastest transition to minimize the time it takes for
the opto-coupler to change state.
If the duration of the external trigger is > t(oc) + t(d), then a valid acquisition trigger is detected.
It is possible to emulate an external trigger using the software trigger which is generated by a
function call from an application.
