The odometer reading in Vertex IFMS is calculated in two distinct ways:

1. OBD based

If the vehicle is fitted with an OBD compliant vehicle tracker, the reading from the vehicle odometer as available in the dashboard of the vehicle can be obtained from its Engine Control Module through the OBD or CANBUS network and shown in the software.

2. GPS based

This method is used where the tracker or the vehicle is not OBD compliant. In this case, the movement of the vehicle as calculated by the GPS coordinates obtained from the GPS satellite system is used to calculate the actual distance travelled by the vehicle on the surface of the earth. This distance is added to the initial odometer reading of the vehicle during the installation of tracker and shown as the current odometer reading in Vertex IFMS. 

The odometer reading obtained from the second method above will not be the same as the meter reading on the dashboard of a vehicle at any given point of time. There are several reasons for this anomaly. The vehicle speedometer gets its readings from a sensor which reads the rotation of the wheel. Based on the rotation and the circumference of the wheel, the distance traveled is calculated. Various factors such as the slip of the wheels, the tyre pressure, wear and tear, the side of the vehicle the sensor is reading etc can influence the reading and we can see that the odometer reading reported by the GPS system is different from that of the vehicle meter.

It is advisable to correct this periodically if accurate odometer readings are important for your operations. In order to do the correction, you have to periodically take manual readings of the vehicle meters and send to us so that we can do the corrections. Based on the historical data we obtain from these corrections, we then apply a correction factor for each vehicle which will help to reduce the variance considerably. After some time, the correction factor ensures that the difference between the odometer readings reported by the GPS and the vehicle are negligible.