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Appendix B: Activate An External LED Message Above a
Preset Speed
Many speed signs have an external VMS type message that gets activated above a preset speed.
This message may spell out text like “SLOW DOWN” or any other message in a local language.
Emoticons like a “sad face” are also commonly used in certain countries. The schematic below
shows how to connect a string of LEDs that can be triggered by the PNL18 above a user set speed
limit. Additionally this message will blink if the user chooses.
Connect as many strings of LEDs as required to form a message. For simplification only two
strings are shown on the schematic. Then physically arrange the LED’s in the form of the
message or emoticon you desire. The message can be programmed to activate above any user-
selected speed. Furthermore this speed can be adjusted in the field through the rotary switch
located on the back of PNL18. For most configuration purposes this eliminates the need to
connect a computer in the field. If you wish to use a “SLOW DOWN” message we have an LED
only board available for purchase. A second “THANK YOU” message (or a “happy face”
emoticon) can be activated below the user-selected speed when connected to pin #1 of J10. Thus
you can build a “SLOW DOWN”/”THANK YOU” type of display easily. Please contact us for
details if you wish to utilize this feature
