Niagara PRO TIPS: Web Charts Axis Options

Niagara PRO TIPS: Web Charts Axis Options

Video Tutorial: Niagara PRO TIPS: Web Charts Axis Options

Overview

This guide covers the axis configuration options available in Niagara 4 web charts, with a focus on new features introduced starting with Niagara 4.6 Update 1. Learn how to control trend gaps, data gaps, and axis scaling behavior to create better visualizations.

What's New in Niagara 4.6 Update 1

The following features were added or changed in Niagara 4.6 Update 1:

• Show Start Trend Gaps - Control visibility of gaps at start trend flags

• Show Data Gaps - Control visibility of gaps for invalid data (default behavior changed)

• Facets Limit Mode - New axis scaling options using point facets

• Chart Min/Max Facets - Custom facet keys for chart-specific scaling

• Chart Limit Mode Facet - Automatic mode selection on chart load

Feature 1: Start Trend Gaps

Understanding Start Trend Gaps

Start Trend Flags appear in history records when:

• The station was just started

• History collection began (history extension was enabled)

• Entering a collection period (for non-24-hour collection schedules)

Visual Indication:
By default, web charts display a gap in the trend line when a start trend flag is encountered. This provides a visual identification that there may be missing data, as the duration or intent of the interruption is uncertain.

Viewing Start Trend Flags

Step 1: Open History Table View

1. Navigate to your history

2. Switch to table view (instead of chart view)

3. Look for records with start trend flags indicated

What You'll See:
Records marked with start trend flags show where data collection was interrupted or restarted.

Configuring Start Trend Gap Display

Step 1: Access Axis Configuration

1. Open your web chart

2. Click the gear icon (configuration)

3. Navigate to the Axis tab

Step 2: Configure Show Start Trend Gaps

• Property: Show Start Trend Gaps

• Default: Yes (gaps are shown)

• Options:

  • Yes - Display gaps at start trend flags (traditional behavior from AX)

  • No - Connect the dots between records, ignoring start trend flags

Result When Set to "No":

The web chart will connect trend lines between records even when start trend flags are present, creating a continuous line without visual gaps.

Feature 2: Show Data Gaps

Understanding Data Gaps

Data gaps occur when records contain invalid data values that cannot be plotted:

• Null status - Not a valid status

• NaN (Not a Number) - Invalid numerical value

• Infinite values - Positive infinity or negative infinity

• Hidden records - Records flagged as hidden

Important Behavior Change:
In Niagara 4.6 Update 1, the default behavior changed to NOT show data gaps, improving the UI aesthetic of web charts.

Types of Invalid Data

Configuring Data Gap Display

Step 1: Access Axis Configuration

1. Open your web chart

2. Click the gear icon (configuration)

3. Navigate to the Axis tab

Step 2: Configure Show Data Gaps

• Property: Show Data Gaps

• Default: No (NEW in 4.6 Update 1 - gaps are hidden)

• Previous Behavior: Gaps were shown by default (AX through 4.6 initial release)

• Options:

  • No - Connect trend lines, ignore invalid data (better UI aesthetic)

  • Yes - Display gaps for invalid data values

Result When Set to "Yes":

The chart will display visible gaps wherever invalid data occurs, making it clear where data quality issues exist.

Result When Set to "No" (Default):

The chart connects trend lines across invalid data points, creating a cleaner, more professional appearance.

Viewing Data Issues in History Table

Step 1: Open History Table View

1. Navigate to your history

2. Switch to table view

What You'll See:

• Records with null status

• NaN values

• Infinite values (∞ or -∞)

• Hidden records (with hidden trend flag)

Use Cases for Hidden Records:

• Erroneous values that shouldn't be displayed

• Data that needs to remain in history but not visualized

• Temporarily removing outliers from chart view

Feature 3: Axis Scaling with Facets

Traditional Auto-Scaling Behavior

Default Behavior:
Web charts traditionally auto-scale the Y-axis based on the data point values being displayed. The axis adjusts to fit the minimum and maximum values in the current view.

New Facets Limit Mode

Starting with Niagara 4.6 Update 1, you can control axis scaling using point facets.

Step 1: Access Axis Configuration

1. Open your web chart

2. Click the gear icon (configuration)

3. Navigate to the Axis tab

Step 2: Configure Facets Limit Mode

• Property: Facets Limit Mode

• Default: Off (retains original auto-scaling behavior)

• Options:

  • Off - Auto-scale based on plotted data values

  • Inclusive - Use min and max facets from the control point

  • Locked - Lock axis to specified range

Using Inclusive Mode

What It Does:

When set to Inclusive, the chart uses the min and max facets from the control point to scale the Y-axis, instead of auto-scaling to the plotted data.

Example:

Control Point Facets:

• Min Facet: 50

• Max Facet: 250

Chart Behavior:

• Y-axis will scale from 50 to 250

• Regardless of actual data values plotted

• Provides consistent scaling across different time ranges

Use Cases:

• Showing valid sensor ranges

• Maintaining consistent scale across multiple charts

• Displaying operational limits visually

Feature 4: Custom Chart Facets

Chart Min and Chart Max Facets

New Capability:
You can now add chart-specific facet keys that override the point's min/max facets for charting purposes.

Adding Chart Facets to Control Points

Step 1: Navigate to Control Point

1. Drill into the BACnet Network (or relevant network)

2. Navigate to the equipment (e.g., Air Handler)

3. Select the control point (e.g., Room Temp)

Step 2: Add Chart Min Facet

1. Click Add New Facet Key

2. Select chart min from the list

3. Enter desired minimum value (e.g., 60)

Step 3: Add Chart Max Facet

1. Click Add New Facet Key

2. Select chart max from the list

3. Enter desired maximum value (e.g., 90)

Step 4: Refresh Chart View

Return to your web chart and refresh the view.

Understanding Facet Priority

Facet Hierarchy:

1. Chart Min/Max Facets (highest priority when using "Off" mode)

   • Used when Facets Limit Mode = Off

   • Chart-specific scaling

2. Min/Max Point Facets (used in "Inclusive" mode)

   • Used when Facets Limit Mode = Inclusive

   • Represents valid sensor/point ranges

Example Configuration:

Point Facets:
- min: 50 (valid sensor range minimum)
- max: 250 (valid sensor range maximum)

Chart Facets:
- chart min: 60 (chart display minimum)
- chart max: 90 (chart display maximum)

Behavior:

• Facets Limit Mode = Off: Chart scales to 60-90 (chart min/max)

• Facets Limit Mode = Inclusive: Chart scales to 50-250 (point min/max)

Why Use Different Facets?

Point Min/Max:

• Represents valid sensor readings

• Defines operational ranges

• Used for validation and overrides

Chart Min/Max:

• Optimized for visualization

• Focuses on typical operating range

• Provides better detail for normal conditions

Example:

• Sensor valid range: -40°F to 120°F (point min/max)

• Typical comfort range: 68°F to 76°F (chart min/max)

Feature 5: Chart Limit Mode Facet

Automatic Mode Selection

New Facet: chart limit mode

This facet allows you to automatically set the Facets Limit Mode when the chart loads, without manual configuration in each chart.

Adding Chart Limit Mode Facet

Step 1: Navigate to Control Point

Navigate to your control point (same as adding chart min/max facets)

Step 2: Add Chart Limit Mode Facet

1. Click Add New Facet Key

2. Select chart limit mode from the list

3. Type: String

4. Value Options:

   • inclusive - Use point min/max facets

   • locked - Lock to specified range

Step 3: Enter Facet Value

Type either:

• inclusive (as a string)

• locked (as a string)

Important: This is a string value, not a selection. Type the word exactly as shown.

How It Works

Automatic Behavior:
When a web chart loads, if it detects the chart limit mode facet on the point, it will automatically apply that mode.

Example Scenario:

Point Configuration:
- chart min: 60
- chart max: 90
- chart limit mode: "inclusive"

Result:
Even though chart min/max are specified, the chart will default to Inclusive mode on load, using the point's min/max facets (not chart min/max) because the chart limit mode facet overrides the default.

Chart Display:
If point facets are min=50, max=250, the chart will scale to 50-250 automatically.

Benefits of Chart Limit Mode Facet

✅ Consistency - All charts for a point use the same scaling mode
✅ No Manual Configuration - Set once at the point level
✅ Centralized Control - Change behavior in one location
✅ Default Behavior - Charts load with correct settings automatically

Configuration Workflow Summary

Quick Configuration Guide

For Individual Charts:

1. Open web chart

2. Click gear icon → Axis tab

3. Configure:

   • Show Start Trend Gaps: Yes/No

   • Show Data Gaps: Yes/No

   • Facets Limit Mode: Off/Inclusive/Locked

For Point-Level Defaults:

1. Navigate to control point

2. Add facet keys:

   • chart min - Set chart minimum value

   • chart max - Set chart maximum value

   • chart limit mode - Set to "inclusive" or "locked"

3. All charts for this point will use these settings

Best Practices

When to Show Gaps

Show Start Trend Gaps = Yes:

• When data continuity is critical

• For commissioning and troubleshooting

• When you need to identify collection interruptions

• In detailed technical views

Show Start Trend Gaps = No:

• For presentation views

• Executive dashboards

• When appearance is priority

• For tenant/customer-facing displays

Show Data Gaps = Yes:

• When monitoring data quality

• During system validation

• For identifying sensor issues

• In maintenance/diagnostic views

Show Data Gaps = No (Default):

• For cleaner UI appearance

• In operational dashboards

• For end-user displays

• When data quality is already validated

Axis Scaling Strategy

Use Off Mode (Auto-Scale) When:

• Data ranges vary significantly

• Viewing different time periods

• Need to see all data regardless of range

• Default behavior is sufficient

Use Inclusive Mode When:

• Want to show valid operational ranges

• Need consistent scaling across charts

• Displaying multiple similar points

• Showing operational limits visually

Use Chart Min/Max Facets When:

• Want chart-specific scaling

• Zooming in on typical operating ranges

• Different visualization needs than validation needs

• Multiple charts need different scales for same point

Use Chart Limit Mode Facet When:

• Want consistent behavior across all charts for a point

• Managing many charts

• Need centralized control

• Want to set defaults at point level

Comparison Table

Coming Soon

In an upcoming video, we'll cover:

• How to change default options for all charts

• Saving charts with custom configurations

• Embedding saved charts in PX files

• Creating chart templates with preset options

Key Takeaways

✅ Niagara 4.6 Update 1 introduced significant improvements to web chart axis configuration
✅ Data gap display now defaults to OFF for better UI aesthetics
✅ Start trend gaps can be hidden for cleaner visualization
✅ Facet-based scaling provides consistent axis ranges across charts
✅ Chart-specific facets allow visualization-optimized scaling separate from point validation
✅ Chart limit mode facet enables automatic configuration at the point level
✅ Multiple configuration levels - individual charts, point-level defaults, and system-wide settings

Quick Reference

Axis Tab Properties

Show Start Trend Gaps: Yes | No
- Default: Yes
- Controls: Gaps at start trend flags

Show Data Gaps: Yes | No
- Default: No (changed in 4.6 Update 1)
- Controls: Gaps for invalid data

Facets Limit Mode: Off | Inclusive | Locked
- Default: Off
- Controls: How axis scaling uses facets

Point Facet Keys

chart min
- Type: Number
- Purpose: Chart-specific minimum axis value

chart max
- Type: Number
- Purpose: Chart-specific maximum axis value

chart limit mode
- Type: String
- Values: "inclusive" | "locked"
- Purpose: Auto-set Facets Limit Mode on load

Presenter: James Johnson
Series:Niagara PRO TIPS
Topic:Web Charts Axis Options
Version:Niagara 4.6 Update 1 and later

YouTube: http://www.youtube.com/@TridiumInc