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LIS - LED in sign Home > Systems > System Optic Master > LED in sign Application range | Features | System description | Function description | Technical Data | PDF-Download
Explanation of type designation The appellation LIS is used for the complete system consisting of the components LIS-LC (LIS-Lamp-Controller), several LIS-SB (LIS-Switchboard) und the power units PSK (Power-Supply-Chain) and PSS (Power-Supply-System), including assembly board and wiring. 
System descriptionThe LED-Control in Sign (LIS) is a control unit particularly designed for the drive of variable traffic sign messages with LED-chains for applications in the field of traffic-engineering. It is installed in the variable traffic sign and consists mainly of the above depicted components LIS-LC and LIS-SB. The extent of the complete build-up of the control unit depends basically on the number of necessary switching outputs and therefore on the number of LIS-SBs. The system build-up with 2 LIS-SB (2x32 switching outputs) is depicted in "LIS system build-up". The system shown is installed in the variable traffic sign. The function of the LIS is to control and monitor the LED-chains according to the given switching command, e.g. from a sub-center. The controller manages the correct allocation of the LED-chains to the positioning code by means of parameters, as well as the adjustment of the brightness of the diodes and of the operational current of the LED-chains depending on their colour, in accordance with the requirements of the traffic sign manufacturer. The currents and voltages on the LED-chains are monitored in order to avoid that fragmentary sign-messages are displayed caused by a blackout of LED-chains, or that unwanted LED-chains go into operation because of malfunctions, changing the message of the sign. If a non-tolerable malfunction happens, the system switches off the energy supply of all LED-chains and sends a corresponding error message to the superordinate controller from where the control commands are being sent. The LIS-LC is designed in the way that an independently functioning system is created. All necessary system-components such as program and data memory, I/O-interfaces, watch-dog with integrated voltage-monitoring for RESET-activation, are located on the circuit board. An operational voltage of 5 V is to be used for the LIS-LC.
Function description The control unit switches and monitors LED-chains in the variable traffic signs according to the commands of the superordinate IOC of the function group 4. The LIS has an RS485 standard interface which complies with the requirements of the "Technical Terms of delivery for Road Stations" (TLS) (local bus). The control unit can be built with up to maximally 32 switchboards. The LED-chains are constantly checked for UGE ( unwanted switch-on) and UGA (unwanted switch-off). The LIS-LC reacts to an UGA-error with the switch-off of the fragmentary rest-symbol. An UGE-error is responded to in several levels, from switching off the according symbols to switching off the complete variable traffic sign. The functionality of the LEDs is monitored in off-mode as well by using the so called "cold chain test". Damaged chains are immediately reported to the superordinate system. The brightness of the variable traffic sign can be adjusted in 16 levels. In stand-alone systems, the day/night changeover can optionally be controlled via an external brightness sensor. In the signs LEDs in the colours red, yellow, green, blue and white are used and serially wired in so called LED-chains. Depending on their colour, the LED-chains are built of differing numbers of LEDs. The number of LEDs in each chain is evaluated according to the "Directive for the Evaluation of LED-chains controlled by the LED-control LIS_V02" and depends mainly on the flux-voltage of the diodes, which is different according to the wavelength of the radiated light. |
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PDF download Download this document as PDF 
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