SCADA to Web: Modernizing Industrial Control Interfaces for a Mobile Workforce

The "air-gap" is no longer a viable security strategy—it's a productivity anchor. Industrial Control Systems (ICS) and SCADA environments are currently trapped in a cycle of "technical archaeology," where mission-critical HMI (Human-Machine Interface) screens are locked inside legacy Windows binaries, Delphi wrappers, or aging Java applets.

For the modern mobile workforce, the inability to access real-time telemetry from a tablet or browser isn't just an inconvenience; it’s a massive operational risk. Yet, the standard industry response—the "Big Bang" rewrite—fails 70% of the time. We are seeing $3.6 trillion in global technical debt, much of it concentrated in industrial sectors where the "if it ain't broke, don't touch it" mentality has led to systems that are now impossible to document, let alone modernize.

TL;DR: Modernizing SCADA to Web requires moving away from manual "archaeology" toward Visual Reverse Engineering, reducing screen migration time from 40 hours to 4 hours by using Replay to extract legacy workflows into documented React components.

The SCADA Modernization Paradox#

Most SCADA systems built between 1995 and 2010 share a common problem: the business logic is inextricably linked to the presentation layer. When a VP of Operations asks for a mobile-responsive dashboard, the engineering team typically faces an 18-month timeline to rebuild the interface from scratch.

The problem isn't the PLC (Programmable Logic Controller) or the data layer—it's the HMI. These interfaces often lack source code, or worse, the original developers are long gone. This leaves Enterprise Architects in a "Black Box" scenario.

Comparison of Modernization Strategies#

⚠️ Warning: Attempting a Big Bang rewrite of a SCADA system without a 1:1 functional map of existing workflows usually leads to "feature drift," where the new system fails to handle critical edge cases present in the legacy version.

From Black Box to Documented Codebase#

The traditional way to move SCADA to Web involves a developer sitting with an operator, recording notes, and trying to recreate every button, gauge, and alarm state in a modern framework like React or Vue. This manual process takes an average of 40 hours per screen.

Replay changes this by using Video as the Source of Truth. Instead of guessing how a legacy alarm acknowledgment workflow functions, you record the actual workflow. Replay’s engine analyzes the visual execution and the underlying data calls to generate documented React components and API contracts.

The Technical Debt Audit#

Before writing a single line of new code, you must understand the "Archaeology" of your system. 67% of legacy systems lack any form of technical documentation. Replay's AI Automation Suite performs a technical debt audit by mapping the legacy screen's state changes to the intended modern architecture.

Step-by-Step: Modernizing a SCADA HMI with Replay#

Step 1: Workflow Recording#

An operator performs standard tasks—such as adjusting a PID loop or acknowledging a pressure alarm—within the legacy SCADA environment. Replay captures these interactions not just as pixels, but as a sequence of state transitions.

Step 2: Visual Extraction and Component Mapping#

Replay identifies UI patterns (gauges, sliders, data grids) and maps them to your modern Design System (Library). If a specific industrial gauge doesn't exist in your React library, Replay generates a functional equivalent.

Step 3: API Contract Generation#

SCADA systems often communicate via proprietary protocols or aging OPC-DA interfaces. Replay identifies the data inputs and outputs during the recording and generates a standardized API contract (OpenAPI/Swagger).

typescript
// Example: Generated API Contract for a Pressure Sensor
// Extracted from legacy WinForms SCADA session via Replay

interface SensorTelemetry {
  sensorId: string;
  currentValue: number;
  unit: "PSI" | "BAR" | "PASCAL";
  status: "NORMAL" | "WARNING" | "CRITICAL";
  lastUpdated: string; // ISO 8601
}

export async function getSensorData(id: string): Promise<SensorTelemetry> {
  const response = await fetch(`/api/v1/sensors/${id}`);
  return response.json();
}

Step 4: React Component Generation#

The final output is a clean, documented React component that preserves the original business logic while adhering to modern web standards.

tsx
// Example: Generated React Component from Replay Visual Extraction
import React, { useState, useEffect } from 'react';
import { Gauge, AlarmBanner } from '@company/industrial-ui';

interface SCADA_HMI_Props {
  nodeId: string;
}

export const PressureMonitor: React.FC<SCADA_HMI_Props> = ({ nodeId }) => {
  const [pressure, setPressure] = useState<number>(0);
  const [isAlarmActive, setIsAlarmActive] = useState<boolean>(false);

  // Business logic preserved from legacy recording:
  // Trigger alarm if pressure exceeds 150 PSI for > 5 seconds
  useEffect(() => {
    const socket = new WebSocket(`wss://scada-gateway.internal/stream/${nodeId}`);
    socket.onmessage = (event) => {
      const data = JSON.parse(event.data);
      setPressure(data.value);
      if (data.value > 150) {
        setIsAlarmActive(true);
      }
    };
    return () => socket.close();
  }, [nodeId]);

  return (
    <div className="p-6 bg-slate-900 text-white rounded-lg">
      <h2 className="text-xl font-bold mb-4">Node: {nodeId}</h2>
      <Gauge 
        value={pressure} 
        min={0} 
        max={250} 
        threshold={150}
        label="Main Line Pressure"
      />
      {isAlarmActive && (
        <AlarmBanner 
          severity="CRITICAL" 
          message="High Pressure Detected - Check Valve 402" 
        />
      )}
    </div>
  );
};

💰 ROI Insight: By automating the extraction of these components, enterprises reduce the time-to-web from 18 months to a matter of weeks. The cost savings on developer hours alone typically cover the modernization project in the first quarter.

Addressing the Mobile Workforce#

Industrial operators are no longer tethered to a control room desk. They are on the factory floor, at remote wellheads, or in transit between facilities. A "SCADA to Web" transition isn't just about changing the UI; it's about enabling E2E (End-to-End) Testing and Observability that legacy systems could never provide.

Replay's generated code includes automated E2E tests based on the original recorded workflows. This ensures that the mobile version of the interface behaves exactly like the legacy version, providing the "source of truth" required in regulated environments like Healthcare (HIPAA) or Financial Services (SOC2).

• •Mobile Responsiveness: Generated components use Tailwind CSS or CSS-in-JS to ensure layout integrity across devices.
• •Offline Capabilities: Modern web workers can be injected into the generated architecture to handle intermittent connectivity in remote industrial sites.
• •Security: Moving from legacy protocols to HTTPS/WSS allows for modern Identity Providers (Okta, Azure AD) to manage access, a feat nearly impossible with legacy SCADA.

💡 Pro Tip: Use Replay's "Blueprints" feature to define your global design system before extraction. This ensures that every legacy screen extracted follows your brand’s modern UI/UX guidelines automatically.

Overcoming the "Documentation Gap"#

The biggest risk in industrial modernization is the "Unknown Unknowns." When 67% of systems lack documentation, every rewrite is a gamble. Replay’s "Flows" feature provides a visual architecture map of how different screens and data points interact.

This "Visual Reverse Engineering" approach creates a living document. If an auditor asks how a specific chemical mixing sequence is validated, you don't have to dig through 20-year-old COBOL or VB6 code. You can point to the Replay Flow—a documented, visual representation of the logic extracted directly from a verified user session.

Frequently Asked Questions#

How long does SCADA to Web extraction take with Replay?#

While a manual rewrite takes 40+ hours per screen, Replay reduces this to approximately 4 hours. A standard industrial dashboard with 20-30 complex screens can be fully extracted and functional in a web environment within 2 to 4 weeks.

Does Replay require access to our PLC or backend code?#

No. Replay works through Visual Reverse Engineering. By recording the HMI/UI session, Replay understands the inputs, outputs, and state changes. This is ideal for regulated environments where backend access is restricted or the source code is lost.

Can Replay handle real-time data protocols like MQTT or OPC-UA?#

Replay generates the frontend architecture and API contracts. During the extraction process, it identifies data-binding points. You can then point these generated hooks to your modern data gateway (e.g., an MQTT broker or an Ignition SCADA backend).

Is Replay secure for industrial environments?#

Yes. Replay is built for regulated industries and offers an On-Premise deployment model. This ensures that your sensitive industrial workflows and recordings never leave your internal network, satisfying SOC2 and HIPAA requirements.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.