Remote Access to Controllers and PLCs
Remote access to a programmable logic controller (PLC) allows a technician to connect from their office as if they were physically on site. They can read process variables, modify parameters, download a program, or analyze a fault diagnosis—without having to travel.
The architecture is based on the Eziwan gateway installed on the site’s OT network. It establishes a VPN tunnel to the cloud, which acts as a proxy for the technician’s connection to the PLC. The PLC “sees” a local connection; the technician “sees” the PLC as if it were on the same network.
Compatibility: Siemens S7-300/400/1200/1500, Schneider Modicon M221/M241/M340, Wago 750, Beckhoff CX, Allen-Bradley, ABB, and any PLC with an Ethernet or RS-485 interface.
Resources:
Getting Started with HMI and Remote HMI
Graphical human-machine interfaces (HMIs)—touchscreens, control panels, and local SCADA systems—can be controlled remotely via remote desktop protocols (RDP, VNC, or a web browser, depending on the model). The technician can view the operator’s screen in real time and interact with it.
Typical use cases: modifying a recipe on a Siemens Comfort Panel, diagnosing an alarm on a local Vijeo Citect SCADA system, configuring a temperature controller.
Resource: Remote Access to Industrial HMI
Remote Access by PLC Brand
Each PLC manufacturer has its own protocol-specific features. We have documented remote access for the major brands:
| Brand / Equipment | Dedicated Guide |
|---|---|
| Siemens S7 (300/400/1200/1500) | Siemens S7 Remote Access |
| Schneider Electric (Modicon M2xx/M340) | Schneider Remote Access |
| Wago (750/1000 series) | Wago Remote Access |
| Beckhoff (CX/IPC) | Beckhoff Remote Access |
| HMI (all brands) | HMI Remote Access |
| Variable-speed drives | Remote access to variable-speed drives |
| Electrical cabinets | Remote access to electrical cabinets |
Remote Diagnostics and Reducing Travel
Remote diagnostics go beyond simple remote access: they involve analyzing the system’s status from the cloud without even opening an interactive session. The Eziwan platform continuously monitors key variables and detects anomalies before a failure occurs.
Examples of preventive detection:
- Gradual drift in a pressure sensor (worn seal)
- Increased power consumption in a motor (bearing nearing end of life)
- Increasing number of PLC restarts (power supply issue)
- Abnormal network latency on a gateway (4G antenna needs to be checked)
This predictive maintenance approach reduces unplanned downtime and schedules maintenance outside of production hours.
Resources:
Zero-Trust VPN vs. Traditional VPN
Eziwan’s zero-trust industrial VPN differs fundamentally from a traditional enterprise VPN:
| Criterion | Traditional VPN | Eziwan Zero-Trust |
|---|---|---|
| Connection Direction | Inbound (open port) | Outbound only |
| Firewall Configuration | NAT rule + port forwarding | No changes required |
| Trust Perimeter | Internal network = trusted zone | Implicit zero-trust |
| Granular access | By network/subnet | By device + user + time |
| MFA | Optional | Built-in by default |
| Logging | Variable | Comprehensive and time-stamped |
| Attack surface exposure | Port exposed to the Internet | No ports exposed |
For a detailed analysis: Industrial VPN vs. Remote Access
Our Remote Access Solutions
| Solution | Description |
|---|---|
| Industrial Remote Access | Overview of OT Remote Access |
| PLC Remote Access | Connection to All Brands of PLCs |
| Siemens S7 | S7-300/400/1200/1500 Specifications |
| Schneider Electric | Modicon M221/M241/M340 |
| Wago | 750 and 1000 Series |
| Beckhoff | CX and TwinCAT IPC |
| Industrial HMI | Getting Started with Screens and Control Panels |
| Variable Speed Drives | Remote Access to Drives and Variable Speed Drives |
| Electrical Cabinet | Remote Cabinet Diagnostics |
| Industrial Remote Diagnostics | Predictive Diagnostics Without Interactive Sessions |
| IIoT Predictive Maintenance | Detect failures before they occur |
| Industrial VPN | VPN architecture for OT networks |
| VPN vs. Industrial Remote Access | Detailed technical comparison |