Success story: Mobile Alerting for Legacy Machines
Starting point: Critical alarms that stay on the shop floor
In many plants, critical machines have been in operation for years and were never designed for modern monitoring or remote access. When something goes wrong, the first “alarm system” is often a flashing light, a local HMI message, or a sound signal on the line.
That works – until it doesn’t.
If an issue occurs at night, during breaks, or in unmanned areas, alarms can remain unnoticed. And even when someone sees the alarm, escalation often depends on phone calls, walkie-talkies, or manual documentation. This slows down troubleshooting and turns small deviations into extended downtime.
Many manufacturing and operations teams want to improve exactly this: faster response to incidents in legacy systems, without redesigning the automation architecture.The goal:
Alert the right people immediately – without changing the machine
The requirements in such cases are clear:
- Use existing data sources in the OT environment
- Detect abnormal conditions early
- Trigger reliable mobile alerts
- Keep engineering effort low
- Avoid major changes to existing PLC programs or machine design
The answer to these requirements are edge-based monitoring workflows with local event detection and mobile incident alerting.
The solution: netFIELD at the edge & SIGNL4 on mobile
The solution combines two capabilities:
Hilscher’s netFIELD enables IT-OT integration by providing industrial connectivity and edge processing close to the machines. It connects to typical legacy environments via:
- PLCs and industrial controllers
- field devices connected through industrial networks
- passive monitoring of industrial Ethernet communication (where changing PLC code is not desired) via industrial communication apps
- On the gateway, netFIELD Apps run the data handling and event logic, including Node-RED for low-code processing.
SIGNL4 by Derdack is used as the alerting and incident response layer. It receives event messages from the edge and distributes them to on-call teams via the SIGNL4 cloud to mobile devices directly to the responsible shopfloor staff. They receive:
- mobile push notifications
- optional SMS or voice calls
- escalation rules and incident workflows
Together, this creates a clear chain:
OT data acquisition (netFIELD Edge Gateways) → edge event detection apps such as Node-RED at the Edge Gateways) → forwarding and distribution via cloud (SIGNL4) → mobile alert (SIGNL4) → fast response at the OT level.
How it works in practice: Mobile alerting workflow in a legacy system
Data stays in the plant – events leave the plant
Instead of sending raw process data to the cloud, the gateway evaluates conditions locally. Only relevant events are forwarded. That keeps traffic low and makes the system robust.
Local logic turns process values into actionable incidents
Using Node-RED on the gateway, OT teams can define simple, transparent rules such as:
- threshold violations (e.g., temperature, pressure, current)
- state changes (e.g., machine stops, mode changes)
- pattern-based checks (e.g., repeated short stops within a time window)
Events are enriched before they are sent
When a condition is detected, the gateways can generate event messages that contain:
- machine or line identifier
- timestamp
- measured value or status
- alarm description and severity
- optional context (e.g., last stable value, affected station)
This ensures that recipients can understand the situation immediately – without calling someone to interpret the alarm.
SIGNL4 delivers and escalates
The gateway sends the event via webhook/API to SIGNL4. SIGNL4 routes it to the responsible group and escalates automatically if nobody acknowledges it in time.
The technician gets a clear call to action
Instead of “something is wrong on line 3,” the technician receives a valuable informations like:
- what happened
- where it happened
- how urgent it is
- what value triggered the alert
- who is currently handling it (once acknowledged)
This changes incident handling from “react when you notice it” to react when it happens.
One incident scenario: From deviation to response in minutes
A typical scenario in a plant involves a legacy machine cell where minor deviations used to go unnoticed until the next manual check.
With the new setup a possible scenario could look like this:
- A process value drifts outside its defined operating range.
- The edge gateway detects the deviation instantly and processes it via a defined Node-Red flow.
- An incident is created and forwarded to SIGNL4.
- The on-call technician receives a mobile push notification based on duty schedules.
- The alert is acknowledged, and the team knows ownership is assigned.
- If no acknowledgment occurs, SIGNL4 escalates automatically.
- The technician reacts early – before the deviation becomes downtime.
The key improvement is not just “more data.” It is a faster, structured response.
Why the edge matters for legacy systems
Legacy environments often require pragmatic integration. Edge processing helps because:
- connectivity stays close to the machines and OT networks
- event detection does not depend on constant cloud connectivity
- the system works even when only limited interfaces are available
- changes can be implemented quickly in Node-RED without large software projects
This makes the approach suitable for step-by-step rollout: start with one cell, then scale.
Deployment options: From one machine to a whole plant
The concept scales in three typical ways:
- Machine-level
One gateway per critical machine or station. Simple starting point for retrofits. - Cell/line-level
One gateway collects and evaluates signals from multiple machines in a production cell. - Plant-wide
Several gateways operate across sites or areas. SIGNL4 acts as the unified alerting layer for all monitored assets.
For larger rollouts, netFIELD also contains centralized edge management functionalities of the edge infrastructure (onboarding, status, update rollout, remote app management), which helps maintain consistent configurations across distributed installations.
Result: Less delay, more transparency, higher operational reliability
By implementing edge-based event detection and mobile alerting, repeatable incident workflows for legacy systems can be established:
- incidents reach responsible teams immediately
- response times improve because ownership is clear and alerts carry context
- escalation works reliably, including during off-hours
- engineers can adjust alert logic quickly as requirements evolve
The success factor is the combination of industrial OT connectivity at the edge with mobile incident alerting and escalation – built for real operations, not just dashboards.
Conclusion
About Derdack / SIGNL4
Derdack is a software company specializing in mobile alerting and incident response solutions for industrial operations and IT environments.
SIGNL4 is a mobile alerting platform designed to ensure that critical alerts reach the right people at the right time. The platform supports multiple notification channels, including push notifications, SMS, and voice calls.
SIGNL4 helps organizations improve incident response processes by providing reliable alerting, escalation management, and mobile incident handling for maintenance teams, service organizations, and operations staff.
About Hilscher
Hilscher Gesellschaft für Systemautomation mbH is a technology company specializing in industrial communication and industrial IoT solutions.
The netFIELD ecosystem provides industrial edge management and data acquisition capabilities for connecting machines, field devices, and industrial networks. Hilscher edge gateways, the centralized edge management platform netFIELD Cloud and netFIELD Apps enable flexible integration of operational technology (OT) environments with higher-level IT systems and digital services.
These solutions are used by machine builders and industrial operators to implement industrial IoT applications such as machine connectivity, condition monitoring, and remote services.
Related links
Avec netFIELD, vous bénéficiez de toute l’expertise de Hilscher en matière de communication industrielle, afin de mettre en œuvre la convergence IT-OT et les concepts de l’Industrie 4.0 en toute fiabilité. La plateforme vous permet d’utiliser, de gérer et de faire évoluer efficacement les passerelles Edge et les applications IIoT, qu’elles soient connectées au cloud, hybrides ou entièrement sur site.
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