You see one of these:
- A sensor is missing from the unit card, or its tile shows nothing.
- A report column shows a dash (—) for a unit.
- A sensor reads 0, or a number that cannot be right.
- In the maintenance reminder form, By odometer or By engine hours stays greyed out.
In reports, a dash and a zero mean different things. A dash means the unit has no sensor for that column, so there is no value. A zero means the sensor was there and measured nothing.
Most fixes on this page change the device's sensors. That needs a user who can edit the device, usually the dealer.
- The sensor is not mapped
- The parameter is not in the messages
- The unit has no sensor of that type
- The expression cannot be evaluated
- The value is outside the bounds and is discarded
- The calibration table returns 0 below its first point
- The sensor is hidden from the unit card
- A maintenance threshold is greyed out
A sensor reads its value from a device parameter through its telemetry fields. A sensor whose telemetry fields are all empty gives no values.
Check
- Open the device's Sensors tab.
- Look for a "Not mapped" tag in Reads from, and a warning stripe on the row.
The counts at the top also say how many sensors are not mapped.
Fix
- Select Edit on the sensor's row.
- Map at least one telemetry field to a device parameter. Choose lists the parameters of the device's last message.
- Select Save.
See Sensors tab and Sensor dialog.
The sensor reads a parameter, such as fuel_lvl, that the device does not send, or sends under another name. Which parameter carries a value depends on the device and its protocol.
Check
- Open the unit's messages for a recent period, with Message Type set to Raw.
See Inspect a unit's raw messages.
- Open a message and enter the parameter name in Search by field name....
Fix
- If the parameter has another name, change the sensor's telemetry field to that name.
- If the device does not send it at all, ask the installer to connect the input or enable it in the device.
Many reports and features need a sensor of a certain type. Fuel reports need a fuel level sensor, and engine hours from a counter need an engine hours sensor. A report then shows a dash for units without one, and the Generate screen warns about them.
Check
- On the template card in the report library, select the line "Available on n of m units".
It lists which units lack which sensor.
Fix
- Add the missing sensor to the device. See Add a sensor.
- Or exclude those units from the report.
See Where report data comes from.
A sensor field with an expression has no value for a message when:
- A parameter in arithmetic or in
>, >=, <, <= is missing from the message, or arrives as text.
- A sensor it refers to has no value itself.
- It uses
convertToInt. The server that computes sensor values has no such function.
A missing parameter inside == or != makes the comparison false instead, so {in4} == 1 ? 1 : 0 gives 0.
Check
- Open the sensor and read its expression.
- Compare each parameter it uses with a raw message.
Fix
- Correct the expression. See Expression reference.
- Select Save.
¶ The value is outside the bounds and is discarded
Lower Bound and Upper Bound on a field's calibration table discard readings outside the range. The app does not replace them with the nearest bound, although the dialog's hint says so. The field then has no value for that message.
Check
- Open the field's calibration table.
- Compare Lower Bound and Upper Bound with the raw readings. Check Apply after calculation: off, the bounds test the raw value; on, they test the converted one.
Fix
- Widen the bounds, or switch Apply after calculation to test the right value.
- Save the sensor.
See Calibration tables.
A calibration table gives 0 for any reading below its first point, whatever that point's value. A fuel probe that reads below the first measured point therefore shows an empty tank.
Fix
- Add a point for the lowest reading the probe can give.
- Save the sensor.
See Create a calibration table.
The Unit card switch on the Sensors tab decides whether the customer sees a sensor on the unit card. A hidden sensor still works: alerts, reports and other sensors use its value. The unit's Visibility Control also hides and orders sensors per unit.
Fix
- On the device's Sensors tab, set the sensor's Unit card switch to Shown.
The change saves at once.
- Or, in the unit's edit screen, open Visibility Control on the device card and turn the sensor on.
See Add or remove a unit's devices.
¶ A maintenance threshold is greyed out
By odometer and By engine hours work only for a unit with that sensor. Until you choose a unit, and for a unit without the sensor, the switch and its fields stay disabled. The form can then say "Device or sensor is not available in the unit". The form also cannot be saved while a threshold you switched on has no sensor chosen in Sensor.
Fix
- Choose the unit first in the reminder form.
- If the threshold stays greyed out, ask your dealer to add an odometer or engine-hours sensor to the unit's device.
- Until then, use the date threshold.
See Maintenance reminder form.
Contact support@getgps.eu with:
- The unit name, the device's IMEI and the sensor name.
- A time when the value was wrong or missing, with your time zone.
- The value you expected.