X64 Xcelera-HS PX8 User's Manual
Technical Specifications
•
75
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 34: External Trigger Input Validation & Delay
Let
t(et) = time of external trigger in
µ
s
t(vt) = time of validated trigger in
µ
s
t(oc) = time opto-coupler takes to change state
t(d) = debouncing duration from 1 to 255
µ
s
trigger high
For an active high external trigger, t(oc) = 0.5
µ
s:
t(vt) = t(et) + 0.5
µ
s + t(d)
trigger low
For an active low external trigger, t(oc) = 4.2
µ
s:
t(vt) = t(et) + 4.2
µ
s + t(d)
Table 33: External Trigger Timing Specifications
Note: Teledyne DALSA recommends using an active high external trigger to minimize the time it
takes for the opto-coupler to change state. Specifically, the opto-coupler response time is 0.5
µ
s
for active high compared to 4.2
µ
s for active low.
If the duration of the external trigger is > t(oc) + t(d), then a valid acquisition trigger is detected.
Therefore, the external pulse with active high polarity must be at least 1.5
µ
s (if debounce time is
set to 1) in order to be acknowledged. Any pulse larger than 5.2
µ
s is always considered valid.
It is possible to emulate an external trigger using the software trigger which is generated by a
function call from an application.
Note 4:Opto-Coupled Shaft Encoder Input Specifications
Dual Quadrature Shaft Encoder Inputs (phase A and phase B) are opto-coupled and able to connect
to differential signals (RS-422) or single ended TTL 5V source signals. The following figure is typical
for each input.
3v3
FB
FB
SE +
220
4.7K
nSE
SE -
Figure 35: Opto-Coupled Shaft Encoder Input Electrical Diagram
•
For single ended TTL 5V signals, the SE- pin is connected to ground. The switch point is ~2V.
•
Maximum input voltage that can be applied is 6V.
•
Each input has a ferrite bead plus a 220 ohm series resistor on the opto-coupler anode.
•
Maximum input signal frequency is 200 KHz.
