# sensors

## Description
An array of sensor objects that make up the fan enclosure object. The sensors are what's monitored to determine the functional state of the fan.

A sensor's functional range is determined by the following equation(where *[target]* is current requested target of the fan):
* Minimum = ([target] * (100 - [`deviation`](deviation.md)) / 100) * `factor` + `offset`
* Maximum = ([target] * (100 + [`deviation`](deviation.md)) / 100) * `factor` + `offset`

Therefore, a fan sensor must be above the minimum and less than the maximum to be deemed functional.

## Attribute Value(s)
* `name` - string
  * The name of the fan tach sensors located under the
`/xyz/openbmc_project/sensors/fan_tach` D-Bus path.
* `has_target` - boolean
  * Whether this sensor D-Bus object contains the `Target` property or not.
* `target_interface` - string (Optional)
  * The D-Bus interface containing the `Target` property. This defaults to `xyz.openbmc_project.Control.FanSpeed` for RPM controlled fans or can be set to `xyz.openbmc_project.Control.FanPwm` for PWM controlled fans.
* `target_path` - string (Optional)
  * The D-Bus full object path containing the `Target` property. This defaults to `/xyz/openbmc_project/sensors/fan_tach`+`name`.
* `factor` - double (Optional)
  * A value to multiply the current target by to adjust the monitoring of this sensor due to how the hardware works. This sensor attribute is optional and defaults to 1.0.
* `offset` - integer (Optional)
  * A value to shift the current target by to adjust the monitoring of this sensor due to how the hardware works. This sensors attribute is optional and defaults to 0.

## Example
<pre><code>
{
  "fans": [
    {
      "inventory": "/system/chassis/motherboard/fan0",
      "allowed_out_of_range_time": 30,
      "functional_delay": 5,
      "deviation": 15,
      "num_sensors_nonfunc_for_fan_nonfunc": 1,
      "monitor_start_delay": 30,
      "fan_missing_error_delay": 20,
      "nonfunc_rotor_error_delay": 0,
      <b><i>"sensors": [
        {
          "name": "fan0_0",
          "has_target": true,
          "target_interface": "xyz.openbmc_project.Control.FanPwm",
          "target_path": "/xyz/openbmc_project/control/fanpwm/PWM0"
        },
        {
          "name": "fan0_1",
          "has_target": false,
          "factor": 1.45,
          "offset": -909
        }
      ]</i></b>
    }
  ]
}
</code></pre>