VC40XX.pdf – Hardware Documentation VC40XX Smart Cameras
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4.2.5 Electrical Specifications of Trigger- / Serial-/ Keypad Interface
The board 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.
Neither the trigger input nor the trigger output has
an inbuilt-in photo coupler. Please ensure
that the electrical specifications of this section are met and provide galvanic isolation to trigger
input and output if necessary.
!
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.
Technical data of trigger input:
input voltage:
3-5 V (TTL, CMOS)
input current:
3mA @ 3V / 5mA @ 5V
limiting resistor:
none
knee voltage:
1.5 V
reverse voltage protection:
none
switching delay:
Max. 2µsec + interrupt latency
Capture delay
Approx 40µsec (constant), for jitter
free operation
Note the modified circuit of the trigger input, due to the additional RS232 interface. Old trigger input
circuits need to be modified in order to prevent damaging the trigger input of the VC40XX camera. The
trigger input now needs to be connected to GND (camera GND). The use of a transistor in the trigger
input circuit is recommended as shown in the following figures.
!
Please also note that the GND of the Trigger/ RS232 interface is not identical with the Power Supply/
PLC GND, GND IN com. (refer to section 4.3).
Suggested Trigger Input Circuit PNP
The 1k
Ω
internal pull down resistor is not included in the initial hardware release (delivery until end of
2005). Please provide external pull down resistor in case the trigger input stays high.
5V Out, Pin 2
Trig In, Pin 6
GND, Pin 3
Trigger Input Circuit
Camera Circuit
1k
Ω
TTL Input
©
1996-2005 Vision Components GmbH Ettlingen, Germany
