Arrow Board Operators Manual V1.2
Page 7 of 12
Controller Operation Modes for Arrow Board
The sequence for the control knob/s is as follows:
OFF
REAR
OFF
NON DIRECTIONAL
WARNING
DOUBLE ARROW
RIGHT ARROW
LEFT ARROW
Controller Operation Mode
ARROW BOARD DISPLAY
OFF
All lamps are OFF
LEFT ARROW
Lamps will display left arrow
RIGHT ARROW
Lamps will display right arrow
DOUBLE ARROW
Lamps will display double ended arrow
NON DIRECTIONAL WARNING (WIG WAG)
Lamps will alternate between top and bottom on
opposite sides.
Fail-Safe Techniques Employed:
Only 1 operation mode can be selected at once via the control knob. It is impossible to select
different flashing modes simultaneously. The flashing lamps of the Arrow Board is mimicked
on the controller display so the operator can see in real time what the sign is displaying.
During the normal operation of the system the AC4S controller communicates continually
with the Arrow Board computer, requesting the current status of the Arrow Board. Should a
non-corrected miscommunication be encountered, this will signal a fault to the AC4S display
to the operator.
The Arrow Board computer has a watchdog timer that will shut down all the lamps should
communication be interrupted, such as a disconnected or severed wire, or a catastrophic
failure of the system. This prevents any possible error of display of an incorrect symbol to
road users.
The Arrow Board computer has an operational voltage range of between 6 and 30 volts
without incorrect operation, and a watchdog timer will reset the computer in the event of a
software malfunction.
The AC4S controller likewise has a watchdog timer and an operational range of between 6
and 30 volts, thus the unit will provide normal function and failsafe operation over an
extended voltage range.
