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CV-M77
6 Functions and Operation
Apart from the standard continuous operation, the CV-M77 features three external triggering
modes, Edge Pre-select, Pulse Width Control mode and Readout Delay mode. These 3 external
triggering modes operate with H non-reset. In H non-reset, the exposure will be synchronized to
the internal HD and the exposure will start at the first HD after the negative going edge of the
trigger (see figure 6-1).
Trigger
Exposure
EDGE PRE-SELECT
shutter time
Read out
int. HD
H non-reset
Figure 6-1: H non-reset relation
6.1 Input/Output of HD/VD Signal
6.1.1 Input of External HD/VD signals
This setting is factory pre-set. The video output is synchronized with external HD/VD signals if
applied. If no ext. HD signal is input the camera will switch to the internal X-tal controlled HD sync.
If no ext. VD is connected the camera will continue with its internal VD.
The external HD/VD signal is factory preset to TTL signals (2.0-5.0V). The external HD/VD signals
can be 75 ohm terminated by setting the S301-1,2 switches on the PK 8308 board to ON (see
switch settings) – the signal input level is then 4.0 Vp-p ±2.0V.
6.1.2 Output of Internal HD/VD signals
In order to output internal HD/VD signals the S303-1,2 switches on the PK 8308 board have to be
set to OFF. The output can be either TTL level or from a 75Ω source by setting the proper S301
switches on the PK 8308 board to OFF or ON (see switch settings).
6.2 Continuous operation
For applications that do not require asynchronous external trigger but run in continuous operation
this mode is used. On the camera rear panel SW1-5 to SW1-7 are set to OFF for normal internal
trigger mode. The shutter time (the exposure time) is selected by SW1-1 to SW1-4. The mode
setting and the shutter setting can be done via RS 232C control.
6.3 External Trigger Mode
The CV-M77 camera features 3 external triggering modes:
1 Edge Pre-select mode. (Asynchronous reset and exposure start by an ext. trigger pulse)
2 Pulse Width Control mode. (Exposure control by the low period of the ext. trigger pulse)
3 Readout Delay mode. (The readout is controlled by the ext. trigger and an ext. VD signal)
For all three triggering modes the exposure will start at the next internal HD as explained above (H
non-reset). The trigger input can be TTL level or 75 ohm terminated by setting the specific S301
switch on the PK 8308 board to OFF or ON (see switch settings). When 75 ohm terminated the
signal input level is 4.0 Vp-p ±2.0V.
6.3.1 Edge Pre-select Trigger Mode
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This trigger mode operates in H non-reset mode. In H non-reset mode the exposure will start at
the first internal HD after the trigger. The trigger input should be longer than or equal to 2 HD (102
µsec.) and shorter than 1msec. The external trigger pulse initiates the capture, and the exposure