
Use expressions and validation when the data source needs to do more than simple data entry.

This is an advanced setup area. It is useful when you want to:

- calculate one field from other values
- normalize or transform incoming values
- reject invalid readings
- reference values from connected data sources

## When to use expressions

Use expressions when a value should be derived instead of entered directly.

Common examples:

- calculate totals from several numeric fields
- convert a raw number into another unit or scale
- populate a field based on another field
- reuse values from connected data sources

## Prepare the data source first

Before you write expressions:

1. Create the main fields you need.
2. Add any connected data sources under **More settings** if the logic depends on other sources.
3. Save the data source so the schema is stable.

This makes expressions easier to test and maintain.

## Add expression-based logic

1. Open the data-source editor.
2. Add or open the field you want to calculate.
3. Enter the expression or formula in the field configuration.
4. Save the data source.

If the expression changes existing reading behavior, Zira can ask whether previous readings should be recalculated.

## Use validation rules

Use validation when a reading should be accepted only if it meets a rule.

Common validation checks include:

- minimum value
- maximum value
- minimum length
- maximum length
- required values
- allowed values

Use these rules when you want to prevent low-quality readings from entering the workflow.

## Write expressions carefully

Keep expressions easier to maintain by following a few rules:

- start with simple formulas before building larger ones
- use clear field structure and labels so the logic is easier to follow later
- add connected data sources only when they are really needed
- review recalculation prompts carefully on active data sources

If a formula becomes difficult to read, split the logic across more than one field instead of forcing everything into a single expression.

## What to expect after saving

After you save:

- derived values can be calculated as readings move through normalization
- validation rules can reject or fail readings that do not match the configured limits
- existing readings may be recalculated if you confirm that step during save

## Get help from AI Assistance

AI Assistance can help you think through:

- which fields to add first
- how to structure a calculated field
- what validation rules fit a use case
- how to break a complex formula into smaller steps

When you ask, describe:

- the fields you already have
- the value you want to calculate
- any ranges or limits you need to enforce

## Read next

- [Fields and Structure](/docs/data-sources/create-and-edit/fields-and-structure) - Organize fields before adding expressions.
- [Advanced Settings](/docs/data-sources/create-and-edit/advanced-settings) - Connect other data sources and save safely.



Use expressions, formulas, and validation rules to calculate values, enforce quality checks, and guide more advanced data-source behavior.

Expressions and Validation


A trim saw camera measures how long a board is before the saw and how long it is after. To do that
it has to know where the saw's **stops** are and what size cut each one makes.

**Trim saw stops** is where you teach it, from the console. Open it beside the live view, let the saw
run, and the camera works the positions out for itself while you watch.

## Open the panel

Open the data source, go to **Remote Control**, and choose **Trim saw stops** from the rail on the
right. The live view starts on its own, and the panel opens next to it rather than over it — a
collection runs for minutes, and you need to watch the boards while it does.

## What a calibration actually is

Two things make up a stop: **where it is**, and **what size it cuts**.

- **Where it is** is measured by the camera. You never enter it, and you cannot nudge it from here.
- **What size it cuts** is the part only you know, so that is the only thing the panel asks you for.

The scale comes from the distance between two different cuts, which is why a camera normally needs
**at least two sizes** before it can measure anything.

## Start a run

Press **Collect**. A setup window opens and asks two things before anything goes to the camera.

**Which side of the board the stops are on.** Pick from the sides the camera offers — **Left**,
**Right**, **Top** or **Bottom**. The list is the camera's own, based on how it is mounted, and it
decides how every board in the run is measured. Pick the side the boards are trimmed from.

**Expected cut sizes**, which are optional. Type the sizes the saw cuts, separated by commas —
`30, 34, 38`. Leave it empty and you label each captured line afterwards instead. Both work; declare
them up front when you already know them, and the panel can warn you about a size that will not
separate cleanly from one the camera already has.

Then press the button to begin.

### If the camera already has stops

A camera that has been calibrated before asks first what this run is for:

- **Keep them and re-measure** — the existing stops keep their sizes. Use this for a saw that has
  drifted, or to add a cut well clear of the ones already set up.
- **Remove them and start over** — forget the calibration first, then collect every cut from
  scratch.

Choosing to start over turns the window into a single confirmation naming how many stops will go.
**The run does not begin by itself afterwards** — watch the applied count drop to zero, then press
**Collect** again. Throwing away a working calibration and starting a new run should not be one
gesture.

Adding one extra size to an already-calibrated saw is the case that catches people out. The camera
matches each new line against the stops it already approved, so a new cut close to an existing one
gets absorbed by it and the run is refused. If a size you typed is going to land too close, the setup
window names it before you start.

### Cameras set up for one cut size

A camera commissioned against a measured reference already has the scale that two sizes would
otherwise provide, so it can be calibrated from **a single cut**. When that applies the window says
so and shows the reference it was given. It is read-only — that reference is entered at the camera,
not from here.

## While it runs

Let the saw work. Each stop the camera finds appears as a captured line, and the panel reports what
it is doing as it goes.

When you have enough, press **Stop**. Then:

1. **Label each line** with the size it cuts. The lines are lettered to match the letters drawn on
   the live video, so you can see which line is which.
2. **Drop any line that is not a real stop** — a stray reading, or something that went past that was
   not a cut.
3. Press **Apply**.

The panel counts labelled lines as you go, so you can see how many are still waiting.

## A run stays open until you close it

Nothing times a collection out. If you close the panel, switch tab, or refresh, the camera carries on
collecting with nothing on screen to say so — and the next **Collect** is refused because a run is
already going.

So a **chip in the data source toolbar** stays visible while a run is unfinished, including one
stopped but never applied, and including a run somebody started at the machine rather than from here.
Open the panel again and either finish the run or cancel it.

## Read next

- [Remote Control](/docs/ai-vision/remote-control) — the rest of the tab: live view, recording, image sampling and device settings.
- [Overview](/docs/ai-vision/overview) — the AI Vision workspace.


Calibrate a trim saw from the console — collect its cut positions by watching boards go past on the live view, label each one with the size it cuts, and apply.

Trim Saw Stops


Use **More settings** when you want to configure how the data source behaves beyond its basic field structure.

## Open more settings

1. Open the editor.
2. Click **More settings** in the top-right toolbar.

The settings that appear depend on the kind of data source you are editing.

## Configure the main settings

Common settings include:

- **Site**
  Use this when the data source is not already locked to a specific site.
- **Next form in sequence**
  Use this when one form should lead users to another form after they finish.
- **Publish to**
  Use this to publish the data source to selected channels.
- **WebhookURL**
  Use this when the data source needs to send information to another system.
- **Type**
  Use this when you need to control the broader device type behind the data source.

## Connect other data sources

Use **Connected data sources** when the current data source needs to reference or calculate against values from other data sources.

This is especially helpful for:

- calculated values
- reference lookups
- multi-source workflows

## Use behavior flags

More settings can also include behavior options such as:

- **Static**
  Use this when the data source should hold a single current record instead of a time-series history.
- **Vlookup Table**
  Use this when other data sources should be able to reference entries from this source.
- **Enable GeoLocation**
  Use this when entries should include geographic location data.

For custom data sources, you may also see collection-related information that helps explain how entries are stored.

## Review AI-generated fields carefully

If you used **AI Assist** to draft the data source:

- confirm that each field has the right type
- review whether a matching metric was selected
- create or select a metric manually when no relevant metric exists yet
- review validation limits before saving

## Save carefully when expressions change

If you edit value expressions on an existing data source, Zira can ask whether existing readings should be recalculated.

Use this carefully when the data source is already in active use.



Configure publish targets, linked forms, device type, connected data sources, and behavior options before you save.

Browse Guides

Expressions and Validation

When to use expressions

Prepare the data source first

Add expression-based logic

Use validation rules

Write expressions carefully

What to expect after saving

Get help from AI Assistance

Read next