SetVariableMonitoring

Asks the station to watch a variable and raise a NotifyEvent when it crosses a threshold or changes.

Version: OCPP 2.0.1
Direction: CSMS → Charge Point
Functional block: Diagnostics

This is the mechanism that replaces polling. Rather than reading a variable repeatedly, the CSMS installs a monitor and the station reports when something happens.

Only variables whose variableCharacteristics.supportsMonitoring is true can be monitored — NotifyReport tells you which those are.

Request

Field	Type	Required	Description
`setMonitoringData`	SetMonitoringDataType[]	Required	One entry per monitor: `value`, `type`, `severity`, `component`, `variable`, and optionally an `id` to replace an existing monitor.

json

[2, "19223201", "SetVariableMonitoring", {
  "setMonitoringData": [{
    "value": 80.0,
    "type": "UpperThreshold",
    "severity": 4,
    "component": { "name": "TemperatureSensor", "evse": { "id": 1 } },
    "variable": { "name": "Temperature" }
  }]
}]

Response

Field	Type	Required	Description
`setMonitoringResult`	SetMonitoringResultType[]	Required	One result per requested monitor, each with a status and the assigned monitor `id`.

json

[3, "19223201", {
  "setMonitoringResult": [{
    "id": 55,
    "status": "Accepted",
    "type": "UpperThreshold",
    "severity": 4,
    "component": { "name": "TemperatureSensor", "evse": { "id": 1 } },
    "variable": { "name": "Temperature" }
  }]
}]

Values

MonitorEnumType

Value	Meaning
`UpperThreshold`	Raise an event when the value goes above `value`.
`LowerThreshold`	Raise an event when the value goes below `value`.
`Delta`	Raise an event when the value changes by more than `value`.
`Periodic`	Report the value every `value` seconds.
`PeriodicClockAligned`	Report at clock-aligned intervals of `value` seconds.

Implementation notes

Keep the returned monitor `id`. ClearVariableMonitoring deletes by id, and without it the only way to remove a monitor is to enumerate them with GetMonitoringReport.

severity here sets the severity of the events the monitor will raise — the same inverted 0-to-9 scale, where 0 is most severe.

Monitors on frequently changing variables generate a lot of traffic. Delta with a sensible threshold beats Periodic on a metered connection.