States

State fields let you classify device or asset readings into named states — such as Low, Moderate, or Critical — and then measure how much time was spent in each state. You write a JavaScript condition that returns true when the entity is in that state, and Trendz aggregates the duration across your chosen time window.

In this example a Machine device reports how many details it produces. The goal is to track the production rate by splitting time into three states:

The condition for Low Production:

var okRate = none(Machine.okDetails);
return okRate < 75;

Steps to create this view:

1. Create a Bar chart.
2. Add Date (RAW) to the X-axis.
3. Add a State field; rename it Low Production.
4. Set field aggregation to DURATION_PERCENT.
5. Write the formula for Low Production.
6. Repeat steps 3–5 for Moderate Production and High Production.
7. In view settings, enable Stack mode, 100% Stacked Bar, and Labels.

Select the State field type from the field type drop-down. Each state field has its own JavaScript formula and DURATION_PERCENT aggregation.

States can combine readings from multiple telemetry fields. In this example the goal is to find when machines enter a Critical state — high pressure combined with low rotation speed — and visualise how often this happens hour-by-hour across the week.

The condition for Critical state:

var pressure = none(Machine.pressure);
var speed = none(Machine.rotationSpeed);
return pressure > 700 && speed < 35;

Steps to create this view:

1. Create a Heatmap chart.
2. Add a State field; rename it Critical.
3. Set field aggregation to DURATION_PERCENT.
4. Write the formula for Critical state.
5. Set the By field to hour vs day of week.

Two aggregation functions are available for state fields:

To access a telemetry or attribute value inside a state formula, call an aggregation function:

var temp = none(Machine.temperature);

• none — the aggregation function (required).
• Machine — the entity name (asset type or device type).
• temperature — the field name.

All three parts are required. You cannot read a raw field value without an aggregation function.

For attributes, entity names, or owner names, use uniq() instead of none().

To compare a text field against a known value:

var currentState = none(machine.status);
return "running" === currentState;

State is determined by the last received telemetry value. If no new data point arrives during an interval, Trendz assumes the most recently seen value is still in effect.

For example, if the condition is temperature > 25 and the last reading was 26, the state remains active until a new reading of ≤ 25 is received. Gaps in telemetry do not automatically end the state.

State formulas are evaluated server-side by Trendz. They are not executed in the browser. Only visualization views support state fields — they cannot be used inside Calculation Fields or Prediction models.

State field formulas can be written in JavaScript (ECMAScript 5.1) or Python (3.8+). You can use any standard language constructs: variable declarations, arithmetic, comparisons, logical operators, and string methods.