docs:monitor: Fill in sensors attribute details
The `sensors` attribute contains a list of sensor objects that make up
the fan enclosure object. The sensors are what's monitored to determine
the functional state of the fan.
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
Change-Id: I9d673efc9ff95d638b9edf68fa0cb45b529657a9
diff --git a/docs/monitor/sensors.md b/docs/monitor/sensors.md
index e5341fb..99c6a75 100644
--- a/docs/monitor/sensors.md
+++ b/docs/monitor/sensors.md
@@ -1,9 +1,54 @@
# 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.
+* `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"
+ },
+ {
+ "name": "fan0_1",
+ "has_target": false,
+ "factor": 1.45,
+ "offset": -909
+ }
+ ]</i></b>
+ }
+ ]
+}
+</code></pre>