Houston Radar PNL10 User Manual
Page 28 of 32
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 PNL10 above a user set speed
limit. The message is activated together with the on-board strobe. Additionally this message will
blink if the user chooses the on-board strobe to blink. The 10Hz strobing effect does not apply to
the message.
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. All LEDs will be lit when the on-board strobe is activated. 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 PNL10. 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 this 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 #4 of P2. 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.
