Success story: Mobile Alerting for Legacy Machines

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.

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:

1. A process value drifts outside its defined operating range.
2.  The edge gateway detects the deviation instantly and processes it via a defined Node-Red flow. 
3. An incident is created and forwarded to SIGNL4.
4. The on-call technician receives a mobile push notification based on duty schedules.
5. The alert is acknowledged, and the team knows ownership is assigned.
6. If no acknowledgment occurs, SIGNL4 escalates automatically.
7. 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.