How to Configure Event Handlers: Email, Scripts, Set Points, and Process

Overview

Event handlers define what happens when an event is raised. Mango by Radix IoT has seven handler types: four built into the core, Email, Set point, Script and Process, and three that come with modules, SNMP, Excel report and Slack message. This guide covers the four core handlers in depth and summarizes the other three.

Handler Types at a Glance

SNMP, Excel report and Slack message appear only when their modules are installed. Slack has its own guide, Configuring Slack Notifications for Mango Alarms.

Creating a Handler

1. Open Event Management > Event handlers and choose New (Create event handler)
2. Pick the Event handler type and enter a Name
3. On the Event types tab, tick the events the handler responds to. One handler can serve many event types, and one event type can have several handlers
4. Configure the type-specific settings below, then Save. Disabled switches a handler off without deleting it

You can also start from the Events page: the link in an event's Event handlers column (Handle this event type) opens the Event handlers page for that event type.

Email Handler

The most common handler type. It sends an email when the event is raised, can escalate while the event stays active, and can send a follow-up when it returns to normal.

Configuration

1. Choose Email as the Event handler type
2. Add Email recipients: Mango users, mailing lists, or email addresses typed in directly
3. Choose the Subject line: Include handler name or Include event message. The rest of the subject is fixed: {alarm level} - {name or message} ({notification type}) - id:{event id}
4. Optionally add context: Include system information, Include previous point values for point events, Include logfile
5. Optionally add Escalation entries, each with an Escalation delay/interval, an Escalation mode (Until inactive (return to normal) or Until acknowledged or inactive (return to normal)), a Maximum emails to send (or Send unlimited emails), and its own Escalation email recipients
6. Optionally tick Send inactive email. It goes to everyone who received the active or an escalation email; tick Override inactive recipients to choose different ones

There is no email on acknowledgement; acknowledging an event only stops escalation in the Until acknowledged or inactive mode.

Custom Email Templates

The email body comes from Mango's FreeMarker templates. To change it, provide a Custom email template. The event is available as evt:

• ${evt.message}: the event message text
• ${evt.alarmLevel}: the alarm level
• ${evt.activeTimestamp}: when the event was raised, in milliseconds; format it with ?number_to_datetime
• ${evt.rtnTimestamp}: when the event returned to normal

Prerequisites

Email handlers need working outbound email under Administration > System settings > Email settings; use Send test email there before relying on them. Setting that up is covered in Configuring Event Handlers and Email Alerts.

Set Point Handler

Writes a value to a settable data point when the event is raised and, optionally, when it returns to normal. Used for automated responses.

Configuration

1. Choose Set point as the Event handler type
2. Choose the Target point. It must be settable
3. Choose the Active action, applied when the event is raised: None, Set to point value (copy another point's current value, which must be the same data type), Set to static value (enter the Value to set), or Set to scripted value
4. Optionally choose an Inactive action from the same list, applied when the event returns to normal

If the write cannot happen (the target point is missing or not settable, or a copied value has the wrong data type), Mango raises a Set point event handler failure system event naming the cause.

Examples

Script Handler

Runs script callbacks when the event changes state. Use it for logic that goes beyond a single set-point operation.

Configuration

1. Choose Script as the Event handler type and pick a Script engine
2. Write the callbacks: eventRaised(event) and eventInactive(event) are required; eventAcknowledged(event) is optional
3. Set Script roles (permission groups). The script reads and writes points with these roles

Example Use Cases

• Multi-step shutdown sequence: Disable equipment in a specific order with delays between steps
• Conditional notification: Send different notifications based on time of day or which device alarmed
• Data logging: Write alarm details to an external system or log file
• Calculated response: Read multiple point values to determine the appropriate action

Process Handler

Runs an operating system command on the Mango server. Use it for integrations with external systems.

Configuration

1. Choose Process as the Event handler type
2. Enter the Active process command, run when the event is raised, and its Active process timeout (s)
3. Optionally enter the Inactive process command, run when the event returns to normal, and its Inactive process timeout (s)
4. Use Test command to try a command before saving

To put event details into a command, tick Interpolate commands (access event properties) and use ${event.property}, for example ${event.id} or ${event.alarmLevel}. Interpolation is also off by default and needs event-handlers.process.interpolation-enabled=true in mango.properties. It is the riskier setting, because text from an event message ends up in a shell command.

Example Commands

• /usr/local/bin/send_sms.sh +15551234567 "High temp alarm on Gen-1"
• python3 /opt/scripts/log_alarm.py --event-id ${event.id} (needs interpolation)

Handler Timing

Each handler type acts at its own points in the event lifecycle:

Multiple Handlers per Event

Several handlers can respond to the same event type. A common combination:

1. Email handler with an escalation entry (operator now, supervisor after 15 minutes)
2. Set point handler (automated safety response)
3. Script handler whose eventInactive does logging and cleanup

Testing Handlers

• Use a virtual data source to simulate alarm conditions safely
• Verify email delivery with Send test email first
• For Set point handlers, test against a virtual point before a real equipment point
• Check ma.log for handler execution errors

Troubleshooting

Tips from the Field

Summary

Mango provides seven event handler types: Email, Set point, Script and Process in the core, and SNMP, Excel report and Slack message from modules. Create them under Event Management > Event handlers and tick the event types they respond to. Use email for notifications (with escalation for follow-up), set point for automated control, scripts for complex logic, and process, once deliberately enabled, for external integrations. Combine several handlers on one event type for layered response strategies, and always test handlers safely before deploying to production.