A odometer is something that measures the total distance a vehicle has traveled. There are two types of odometers in GpsGate. One that is handled by the device. And another that is a server side odometer.
Device Odometer. Many but not all GPS trackers have a built in odometer. The main advantage of having a odometer in the device is that it typically measure distance every second. And if the device let's say sends a position up to the server every minute, the distance calculation will be more accurate compared to if the server did it only by using the position updates.
First of all you need to enable the odometer for the device. This is typically done by sending a command to the device. Please check the device documentation.
And as a second step you enable the Device Odometer in the Device Mapper. You find the Device Mappers in the Admin menu. Step Device Odometer in Step 2. when editing the Device Mapper.
Server side _Odometer is a GpsGate Accumulator, that is a new type of variable introduced in GpsGate Server v3.1.
It will accumulate the distance traveled for a vehicle over time. You activate it under "Accumulators" when editing a vehicle/device. Right click on the vehicle and select "Edit User". You can also set a new _Odometer value at any time.
If device odometer is active, the _Odometer will use the device odometer. Otherwise GPS distance will be used. GPS distance is the distance between every position update sent from the device to the server.
_Odometer is used in Driver Journal. It can be used in all Event Rules, and you see the value in the Status tab.
Reports and tracks
All reports and tracks will use the enabled odometer. If server _Odometer is used it will be used for tracks and reports. If only device odometer is enabled it will be used for tracks and reports. If no odometer is enabled GPS distance will be used. That is the distance between all position saved by the server.
When you change odometer, you need to reprocess reports and tracks for the change to take effect on historical data. New data will always use the current selected odometer.
Use the "Developer Tools" to reprocess historical data. Note that reprocessing takes a long time and slows down your server. It should be used sparsely: