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Firmware version 1.10 - Document version 1.06 - eng
LTDVE1CH-40F | INSTRUCTIONS MANUAL
4. General description
Any machine vision application employs some kind of light controller. Light controllers are widely
used to both optimize illumination intensity and obtain repeatable trigger sequencing between lights
and vision cameras.
This controller is a compact unit that includes power supply conditioning, intensity control, timing
generation and advanced triggering functions.
The controller can be set up using a PC with serial RS485 or Ethernet interfaces. Configurations are
saved in non-volatile memory so that the controller will resume operation after a power cycle.
For older firmware versions, please contact us on
manual.
4.1. Benefits of current control
Most LED manufacturers suggest their products to be driven using a constant current source, not a
constant voltage source. This is because, using a constant voltage driving, small variations in
temperature or voltage at the LEDs can cause a noticeable change in their brightness.
Brightness control with voltage is also very difficult because of the non-linearity of brightness with
voltage. On the contrary, the brightness is approximately linear with current, so by driving the LEDs
with a known current, intensity control is linear.
4.2. Operating mode
This strobe controller has one programmable, current-controlled light output. The light output can be
used in pulsed or continuous mode.
In pulsed mode the light is switched on only when necessary. A digital input is used as a trigger
source. When a rising or falling edge on the trigger signal is detected the output is pulsed for the
programmed amount of time.
Using this technique, it is possible to obtain excellent steady images of moving objects. The camera
can be set for an arbitrary long exposure time and the light turned on for a shorter time, just enough
to freeze the motion. This helps to overcome the uncertainty issues usually related with integration
start which, to some degree, afflict most commercial cameras.
The delay from the trigger to the output pulse, the width of the output pulse and the intensity of the
output pulse are all independently configurable. The pulse delay can range from 0 µs to 1 s. The
pulse width can range from 1 µs to 1 s.
In continuous mode the light is always switched on, independently from the trigger signal. Using this
technique, the maximum current value for the channel has to be limited in order to prevent the
overheating of the controller.
The current ranges are:
•
Low current, up to 500 mA (with a resolution of 2 mA)
•
High current, up to 40 A (with a resolution of 40 mA)
The controller must be powered with a fixed supply voltage of 24 V DC. There is an internal DC/DC
converter that can be programmed to provide any voltage between 5 V and 190 V for supplying the
output drivers. This allows a large number of different lights to be efficiently driven.
The DC/DC converter is power limited to around 60 W. Limit maximum continuous current to:
•
4 A at a maximum voltage of 15 V
•
2 A at a maximum voltage of 30 V
In any case, if the light is driven continuously limit the DC/DC converter output voltage to a maximum
