M. H. Corbin, LLC OBD-II Vehicle Distance Translator
Technical Manual
Version 3.0
Page 3 of 9
2. Overview
2.1.
Summary
The M. H. Corbin OBD-II Vehicle Distance Translator (VDT) is designed to translate OBD-2
vehicle speed data into a frequency of digital pulses for use by the NuMetrics NiteStar Distance
Measuring Instrument System (DMI).
2.2.
Concept of Operations
The VDT board connects via OBD-II port to the ve
hicle’s ECU, and via a cable to the
DMI.
Approximately every 500ms, the VDT polls the vehicle’s speed from the ECU via the
OBD-2 port.
o
VDT calculates rate of distance being travelled using this speed data from the
ECU
o
VDT triggers periodic digital pulses (1 pulse per .9113444 feet travelled) to the
DMI based on the vehicle speed.
o
As the vehicle decelerates/accelerates, the period of the digital pulses is adjusted
to reflect this change in rate at which distance is travelled.
DMI utilizes digital pulses to record total distance traveled.
VDT detects when vehicle has been turned off/on so that user can leave device plugged
in without draining battery.
3. Vehicle Distance Translator Installation
Many vehicles only allow the ECU to communicate when the ignition key is in the ON position.
For best results, the first time the unit is connected to the vehicle, ensure the vehicle is on and
the engine running. This ensures the vehicle’s ECU is fully operational before the VDT begins
attempting communications. Once the un
it has been verified to work with the user’s vehicle, the
VDT may be left plugged into the OBD-II port when the vehicle is shut off. To use the VDT:
1. Start vehicle.
2. Pair the OBD-
II DMI Translator with the vehicle by connecting it to the vehicle’s OBD-II
port, shown in Figure 1.
Figure 1.
OBD-2 port in vehicle.
Summary of Contents for LLC OBD-II
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