1
MAN #650398:B
GPS-50-1
GPS Speed and Bus Interface Module
BAT
TER
Y
GRO
UN
D
I/O
I/O
SPEE
D 2
ACC
PW
R
SPEE
D 1
www.dakotadigital.com
605-332-6513
GPS-50-1
GPS INTERFACE
CRUI
SE
To gauge control box
or another BIM
Connect to main
chassis ground
+12V
CONSTANT BATTERY POWER
(fused 5 - 20 AMP max)
+12V
KEY ON POWER
(fused 5 - 20 AMP max)
setup/status switch
AC speedometer output.
Standard speedometer output.
Cruise control speed output.
This Bus Interface Module can be used to provide an accurate speedometer signal with most manufacturer
s’ gauges and
also with a Dakota Digital system to provide speed, compass, clock, and altimeter functions. There are two speedometer
outputs to work with standard speedometers and a dedicated cruise control output. There are two interface (I/O) ports on
the module for use with a Dakota Digital gauge system. Either one can be connected to the gauge system or to another
module, allowing several units to be daisy chained together. Do not connect the I/O port to anything other than a Dakota
Digital gauge or BIM. Do not mount the module in the engine compartment; it should be mounted in interior of the vehicle.
Make sure the module is securely mounted and not hanging loose.
It uses an internal acceleration sensor which
cannot accurately track the vehicle acceleration if it is loose.
The speed data does not use one of the
16 available bus ID’s like other Dakota Digital BIM units do. Speed data is
transmitted and updated every 0.1 second. The remaining data is sent one at a time in sequence along with any other
BIM modules present on the system.
The GPS speed signal can be momentarily incorrect due to interference from overpasses, tunnels, and nearby structures.
To avoid this problem, the system stabilizes the speedometer reading by constantly comparing it with an internal
acceleration sensor. When the key is off, the system goes into a very low power standby mode and only occasionally
wakes up to update GPS readings so that it is ready to start operating as soon as the key is turned on.
Initial setup
Once the module is mounted securely and wired, there are a few internal tasks the GPS module will complete on its own.
First,
the module needs time to acquire and track the satellites. This typically won’t work inside a steel building, so have
the vehicle outside to speed up the process. There is a dot in the upper right of the display that will be on steady or on
and flashing any time the key is on. The dot in the top center of the display will be on steady once it has gotten a GPS
satellite fix. The unit won’t operate until it gets a fix and this may take 1 – 15 minutes depending on various things. This
delay is only for the initial GPS fix. After this it will typically begin operating within a few seconds of turning the key on.
The second step is to let the internal acceleration sensor learn how it is mounted in the vehicle. You can mount it
securely in any position you want. When you are sitting still it learns which way is up. In order to learn which way is the
front of the vehicle you need to accelerate or decelerate on a straight stretch of road. Accelerate or decelerate for at least
2.5 seconds and make sure your speed changes by at least 10 mph. This procedure only needs to be done initially and
doesn’t need to be repeated unless you move the module to a different mounting location.
If you move it to a new mounting location or a different vehicle, enter the setup menu and select the
option to speed
up learning the new mounting position.
IMPORTANT NOTE!
When used to operate a cruise control, see the special
mounting requirements on the bottom of page 4.
