VC72XX_HW.pdf – Hardware Documentation VC72XX Smart Cameras
1996-2016 Vision Components GmbH Ettlingen, Germany
3.2.5 Electrical Specifications of Trigger & Serial (RS232) Interface
The trigger interface features a dedicated fast TTL trigger input (for use as image capture trigger) and
a fast TTL trigger output (as strobe-light trigger). Since both signals are fast at a very low noise
margin, it is recommended to keep the cable as short as possible. Use shielded cable for this purpose.
Please note that input and output are not protected against over current. The output is neither
protected against short circuit nor reverse voltage spikes from inductive loads. The trigger input
assures constant delay without jitter.
The trigger input/output has been changed from 3.3V TTL to 5V TTL with board revision
1.2. Moreover these interfaces are now opto-isolated. The table below shows for each camera
model from which serial number the camera has board version 1.2.
Board revision 1.2 from serial number
Technical data of trigger input:
input current: 3mA @ 3V / 5mA @ 5V 3mA @ 3V
reverse voltage protection: None None
switching delay: Max. 2µsec + interrupt latency Max. 2µsec + interrupt latency
Capture delay Approx 40µsec (constant), for
jitter free operation
Approx 40µsec (constant), for
jitter free operation
The use of a transistor in the trigger input circuit is recommended as shown in the following figures.
These are sample circuits only – please check the final circuit layout as this depends largely on the
sensor / equipment connected.
Please also note that the GND of the Trigger / RS232 interface IS IDENTICAL to the Power Supply /
PLC GND, GND IN com. (different from the VC4XXX series).
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