External Trigger Modes - JAI CV-A11 Operation Manual

6.4. External Trigger Modes

This camera has 6 external asynchronous trigger modes, which can be set by RS-232C commands.
1. Edge Pre-select Mode.TR=1
2. Pulse Width Control Mode. TR=2
3. Frame Delay read out mode. TR=3
4. Long Time Exposure Mode. TR=4
5. Start/stop Mode. TR=5
6. Smearless Read out mode. TR=6
The default accumulation is HD synchronously accumulation (HC=0). The accumulation starts at
the first HD after the trigger leading edge. Details are shown in fig.15.
In PWC mode (TR =2) and Frame Delay readout (TR=3), the accumulation mode HC can be set to
asynchronous accumulation (HC=1). The exposure will start immediately at the leading edge of
the trigger pulse without waiting for the HD. Fig. 16. below shows the details.
In Edge pre-select TR=1 and smearless TR=6, the shutter mode can be SM=0 or SM=1.
Smearless read out will reduce the smear caused by highlighted zones seen in images taken with
a short shutter speed. Before the accumulation can start, a fast dump read out is performed. It
takes 28H from trigger leading edge to start of accumulation.
Important notes on using trigger modes
•
The HD synchronized accumulation starts at the first HD after the trigger leading edge.
To avoid the <1H jitter caused by this delay, synchronize the external trigger to HD as
shown in fig. 14. The trigger level translations should be placed inside A, which is 8 µsec.
•
Do not input a new trigger before the previous video is read out. (WEN is high).
Fig. 14. Trigger/HD timing.
t t
t t
1 1 2 2
HD HD HD
Trigger
Trigger Trigger
Accum Accum
Accum
Xsub Xsub Xsub
Xsg Xsg Xsg
EEN
EEN EEN
Fig. 15. Pulse Width H synchronous accumulation.
t t
t t
1 1
2 2
H D H D
T rig g e r T rig g e r
A cc u m A cc u m
X s u b X s u b
X sg X sg
E E N E E N
Fig. 16. Pulse Width H asynchronous accumulation.
CV-A11
Pre-selected exposure. (SM=0, SM=1)
Pulse width controlled exposure. (HC=0, HC=1)
PWC exposure read out by ext. VD. (HC=0, HC=1)
Exposure is interval between ext. VD.
Exposure start by trigger and stop by ext. VD
EPS Exp. after fast dump readout.(SM=0, SM=1)
t t t t t t
3 4
3 4 5 5
t t
t t
3 3
4 4
- 8 -
A=8 µsec
Note:
Xsg and Xsub are
internal signals in the
camera. They are shown
in the timing diagram
for better
understanding.