A new production line needs to connect a PLC, HMI, remote I/O, drives, an industrial PC and SCADA. The first question isn’t “Which Ethernet switch should I buy?” It’s “How should the whole industrial Ethernet network be designed?”
A reliable network depends on decisions about devices, topology, switches, cabling, IP addressing, bandwidth, redundancy, environmental conditions, management and security. This step-by-step guide shows how to build an industrial Ethernet network, from requirements to commissioning.
How Do You Build an Industrial Ethernet Network?
Building an industrial Ethernet network involves defining the devices and traffic requirements, selecting a topology, choosing suitable industrial Ethernet switches and cabling, planning IP addresses, configuring the network, testing connectivity, and documenting the installation.
Industrial Ethernet uses the same networking fundamentals as standard Ethernet. What differs is the hardware: environmental, mechanical, electrical, reliability and management requirements.
Step 1: Define What the Network Needs to Connect
Start with a device list. Typical devices include PLCs, HMIs, remote I/O, VFDs/drives, robots, industrial cameras, sensors, SCADA systems, industrial PCs, edge gateways and engineering workstations.
| Device | Quantity | Ethernet Ports | Network Requirement |
|---|---|---|---|
| PLC | 1 | 1–2 | Control communication |
| HMI | 2 | 1 | Operator interface |
| Remote I/O | 4 | 1 | I/O communication |
| Industrial PC | 1 | 1 | Data/SCADA |
| IP Camera | 4 | 1 | Video traffic |
This list drives the port count and the architecture. Note which devices carry control traffic and which carry bulk traffic such as video.
Step 2: Choose the Industrial Ethernet Topology
Industrial network topology describes how devices and switches are linked:
- Star: devices connect back to a central switch.
- Line: devices connect one after another.
- Ring: switches or devices form a redundant path.
- Tree: switches connect in hierarchical layers.
| Topology | Typical Benefit | Main Consideration |
|---|---|---|
| Star | Simple management | Central switch dependency |
| Line | Simple machine layouts | Link failure can affect downstream devices |
| Ring | Redundancy | Requires appropriate redundancy support |
| Tree | Scalable architecture | More complex design |
No topology is universally best. Choose based on machine layout, availability needs and device support.
Step 3: Decide Between a Managed and Unmanaged Switch
An unmanaged industrial Ethernet switch suits simple networks where basic connectivity is enough and advanced monitoring or configuration isn’t needed.
A managed industrial Ethernet switch is useful when you need:
- VLANs
- QoS
- Port diagnostics
- Network monitoring
- Redundancy
- Traffic management
- Configuration control
Managed switches give more visibility and control, but not every network requires them.
Step 4: Calculate the Number of Switch Ports
Required ports = connected Ethernet devices + uplinks + spare capacity
For example, a machine with 1 PLC, 1 HMI, 4 remote I/O devices, 2 drives and 1 industrial PC needs 9 Ethernet connections before uplinks and spares. Leaving some spare capacity makes later expansion easier. How much depends on your application.
Step 5: Choose the Right Industrial Ethernet Switch
Port count alone should not decide the switch. Evaluate:
- Port count: how many devices must connect?
- Port speed: 10/100 Mbps, Gigabit or higher, based on your requirements.
- Copper vs fibre: choose by distance, EMI environment, architecture and bandwidth.
- SFP ports: useful for flexible fibre or copper uplinks.
- Managed features: VLAN, QoS, diagnostics, redundancy, monitoring.
- Environmental rating: temperature, vibration, humidity, ingress protection and installation environment.
- Power input: check the voltage range and power architecture.
- Certifications: verify those required for your application and market.
Step 6: Select the Right Industrial Ethernet Cables
A good switch can’t compensate for unsuitable or damaged cabling. Consider:
- Copper Ethernet: shielded or unshielded depending on the EMI environment. Shielding isn’t always required.
- Connectors: match the environment and vibration conditions.
- Fibre: multimode or single-mode, chosen by distance and architecture.
- Distance: stay within the limits of the cable and media type.
- Routing: keep clear of power cables where possible.
- Mechanical and environmental conditions: flexing, oil, moisture, temperature.
Step 7: Plan IP Addresses and Network Configuration
Plan the IP address, subnet mask, default gateway (where required) and device names. Avoid duplicate addresses and document everything. Whether to use DHCP or static addressing depends on the application and protocol.
Example only:
- PLC: 192.168.10.10
- HMI: 192.168.10.20
- Remote I/O: 192.168.10.30
- Industrial PC: 192.168.10.40
These are illustrative addresses. Follow your organization’s network architecture.
Step 8: Plan Industrial Network Redundancy
Redundancy matters when downtime from a link or switch failure is costly, such as in critical production systems. Ring topologies, link-failure protection and switch redundancy are common approaches. Examples include RSTP, MRP and other vendor or industry mechanisms.
Choose according to your industrial protocol, architecture, equipment support and recovery requirements. Not every industrial network needs redundancy.
Step 9: Consider VLAN, QoS and Network Segmentation
- VLAN: logically separates traffic into segments.
- QoS: can prioritise selected traffic when traffic classes share resources.
- Segmentation: separates operational or functional areas.
An example layout:
- Control network: PLC and I/O
- HMI/SCADA network: operator systems
- Video network: industrial cameras
The right design depends on the application and cybersecurity architecture. VLANs and QoS aren’t mandatory for every installation.
Step 10: Connect and Configure the Network
A practical industrial Ethernet installation sequence:
- Install switches
- Connect devices
- Label cables and ports
- Apply IP addressing
- Configure managed-switch features if required
- Configure redundancy if required
- Verify link status
- Check port speeds
- Test device communication
- Document the final configuration
Documentation pays off during faults. Keep a network diagram, IP address table, switch configuration, port-to-device mapping and cable identification.
Step 11: Test the Network Before Production
Industrial network commissioning should check:
- Connectivity: can all devices communicate?
- Link status: are links stable?
- Port statistics: any CRC errors, drops or abnormal counters?
- Application communication: can the PLC reach I/O, HMI and other required systems?
- Redundancy: if configured, does the network respond correctly to the relevant failure?
- Traffic: is utilisation within expected levels?
- Environment: are switch temperature, power and installation conditions within specifications?
Test under realistic operating conditions where practical. Also check protocol-specific requirements for PROFINET, EtherNet/IP, Modbus TCP or other protocols you use.
Step 12: Document and Maintain the Network
Design doesn’t end at installation. Maintain:
- Topology diagram
- IP address list
- Switch configurations
- Device inventory
- Firmware/software versions
- Port mapping
- Cable documentation
- Maintenance history
Current records shorten troubleshooting when a fault occurs.
Example Industrial Ethernet Network
PLC + HMI + Remote I/O + Drives
↓
Managed Industrial Ethernet Switch
↓
Industrial Uplink
↓
SCADA / Industrial PC
↓
Factory / Enterprise NetworkA redundant alternative:
Switch A ↔ Switch B ↔ Switch C
↖─────────────────────↙The switch aggregates machine devices, the uplink carries data upward, and the industrial PC or SCADA collects and presents data. A connection to the factory network should pass through appropriate architecture and security controls. This is conceptual; not every factory should use the same design.
Common Mistakes to Avoid
- Choosing a switch only by port count
- Ignoring environmental specifications
- Using unsuitable cabling
- Creating accidental network loops
- Skipping IP planning
- Forgetting spare ports
- Ignoring bandwidth requirements
- Mixing protocols without understanding their requirements
- Configuring redundancy incorrectly
- Connecting OT equipment to broader networks without proper architecture and security controls
- Failing to document the network
Frequently Asked Questions
What equipment is needed to build an industrial Ethernet network?
Typically, industrial Ethernet switches, suitable copper or fibre cabling, connectors, power supplies and the end devices. Requirements vary by application.
How do I choose an industrial Ethernet switch?
Match port count, speed, media type, management features, environmental rating, power input and certifications to your application, not port count alone.
What topology is best for an industrial Ethernet network?
It depends on machine layout, availability needs and equipment support. Star, line, ring and tree each suit different situations.
Do I need a managed industrial Ethernet switch?
Only if you need features such as VLANs, QoS, diagnostics, monitoring or redundancy. Simple networks may work with unmanaged switches.
How do I assign IP addresses to industrial Ethernet devices?
Plan a documented scheme under your network architecture. Static or DHCP addressing can both be used, depending on the application.
Does an industrial Ethernet network need redundancy?
Not always. It depends on availability requirements, the cost of downtime and what your devices and protocols support.
Conclusion
The process is: define devices → choose topology → select switches → choose cables → plan IP addressing → configure the network → test → document. A good industrial Ethernet network is designed around the application, not just the switch.
When selecting industrial Ethernet switches, Comxus encourages matching them to port requirements, network topology, environmental conditions, management features and reliability requirements.
Read Also: RSTP vs MRP: What’s the Difference?
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