Wake on LAN for Industrial and Vision Computers: Remote Power On Explained

Wake on LAN (WoL) is a network standard that turns a computer on remotely by sending a special Ethernet frame, called a magic packet, to its network card. The network card stays powered while the computer is asleep or shut down, watches for a packet containing its own MAC address repeated 16 times, and signals the motherboard to power up when it sees one.

Edge computing has brought flexibility and decentralisation to manufacturing, but it has also put hundreds of inference PCs in places nobody visits often. Two drawbacks follow: network load from systems that run when they do not need to, and the cost of reaching a computer that is switched off. Remote power control solves both. A computer can be turned on and off by a command from another system, triggered by a schedule, a sensor, a control platform or an operator.

This guide explains how Wake on LAN works, compares it with the other ways of powering an industrial computer on remotely (RTC wake, power-on after AC loss, ignition sensing, remote power switches and out-of-band management), shows how to enable and troubleshoot WoL in the BIOS, Windows and Linux, and covers waking computers across subnets and over the internet. It then applies all of that to machine vision, where shift-start wake-up, staged boots and camera sequencing make remote on/off especially useful.

Wake on LAN dates from 1995, when AMD and Hewlett-Packard introduced the Magic Packet format, and it became standard on PC network cards with the ACPI power management specification. It relies on three things working together: a network card that stays powered in standby, a motherboard that lets that card raise a wake event, and a magic packet that reaches the card.

The magic packet

A magic packet is a frame whose payload contains six bytes of 0xFF followed by the target computer’s 48-bit MAC address repeated 16 times, 102 bytes in all. The network card does not need an IP address or an operating system to recognize it; it simply scans incoming frames for that pattern. Senders usually wrap it in a UDP datagram to port 9 (the discard port) or port 7, sent to the subnet’s broadcast address, although it can also be sent as a raw Ethernet frame with EtherType 0x0842. Some cards accept an optional six-byte SecureOn password appended to the packet.

Power states

ACPI defines the power states a computer moves through. WoL works from sleep (S3), hibernate (S4) and soft off (S5), provided the board keeps standby power to the network card. It cannot work from mechanical off (G3), when the power supply is switched off or the DC feed is removed, because nothing on the board is powered to listen.

Wake on LAN is one of several ways to start an industrial computer without pressing its power button. The right choice depends on what triggers the start-up and whether the computer has lost power completely. Most unattended systems use two or more together.

Two settings make most of these work reliably. Set the BIOS to power on when AC is restored, so a site recovers from a power cut without a visit, and enable WoL or RTC wake for planned starts. For a system that hangs rather than switches off, a watchdog timer restarts it automatically, and a power cycle from a switched supply is the last resort.

Ignition sensing on vehicles

On vehicles and rolling stock, the ignition signal does the job WoL does on a network: the computer starts when the engine starts and shuts down cleanly after a programmable delay when it stops. Our guide to configuring ignition control covers delay timers and low-voltage protection, and the ignition control FAQ gives the short version.

Out-of-band management

Out-of-band management goes further than WoL. A management controller on a separate network path can power the computer on and off, reset it, show its console and, on some systems, mount a recovery image, even when the operating system has failed. On Intel systems this is Intel vPro with AMT; on servers it is a baseboard management controller. Our guide to Intel AMT and out-of-band management compares the options for industrial PCs.

WoL has to be enabled in three places: the firmware, the network card and the operating system. Missing any one is the usual reason it does not work.

1. BIOS or UEFI

In the BIOS setup, enable the option that lets the network card wake the system (our comparison of UEFI vs BIOS explains the two firmware types). Names vary by board maker: Wake on LAN, Wake on PCIe, PME Event Wake Up, or Resume by PCI-E Device. Then disable the options that cut standby power: ErP or EuP Ready, Deep Sx, or Deep Sleep. These exist to meet EU ecodesign rules for very low off-mode power, and with them enabled the network card is unpowered in S5. While in the BIOS, set the power-on-after-AC-loss behavior too.

2. Windows

In Device Manager, open the network adapter’s properties. On the Power Management tab, tick Allow this device to wake the computer and Only allow a magic packet to wake the computer. On the Advanced tab, enable Wake on Magic Packet and, where listed, Wake from shutdown. Windows Fast Startup can stop some network drivers waking the system from S5, so turn it off in the power options if WoL works from sleep but not from shutdown. A Windows IoT Enterprise image should have these settings baked in so every system in a fleet behaves the same way.

3. Linux

Check support with sudo ethtool eth0 | grep Wake-on, replacing eth0 with the interface name. Supports Wake-on: pumbg lists the options; g means magic packet. Enable it with sudo ethtool -s eth0 wol g. The setting is lost at reboot on many systems, so make it persistent: with NetworkManager use nmcli connection modify <name> 802-3-ethernet.wake-on-lan magic, or with systemd-networkd add WakeOnLan=magic to a .link file for the interface.

4. Send the packet

From another computer on the same subnet, a tool such as wakeonlan 00:1B:21:3A:4C:5D or etherwake on Linux, or a PowerShell script on Windows, sends the magic packet. Control platforms, building management systems and many industrial software packages can send it too. Record each computer’s MAC address for the port that will be used for WoL, because only some ports on a multi-port system may support it.

A magic packet sent to a broadcast address stays inside its own subnet, because routers do not forward broadcasts by default. Waking a computer on another VLAN, at another site or over the internet needs one of the approaches below.

WoL has no authentication in its basic form: any device that can reach the network card can wake it. On an OT network that is usually acceptable, because waking a computer is low risk, but it is one more reason to keep magic packets inside a segmented network and reach it through a VPN rather than an open port. The TCP and UDP port used does not matter to the card, only whether the frame arrives; TCP vs UDP explains why UDP is used.

Does Wake on LAN work over Wi-Fi?

Usually not from shutdown. Wake on Wireless LAN (WoWLAN) exists, and some laptops and Wi-Fi modules support it from sleep, but most industrial computers and Wi-Fi cards do not keep the radio associated in S5. Use a wired port for WoL on fixed installations.

Most WoL faults come down to standby power, settings that do not persist, or packets that never arrive. Work through the table in order.

Intel I210, I225 and I226 controllers, common on industrial boards, support WoL, but the board design decides which ports keep standby power. Check the computer’s manual for the WoL-capable port before wiring a cabinet. A managed switch with storm control or port security can also filter broadcast traffic, so test WoL through the actual network, not a bench switch.

Through advances in neural networks and machine learning models, industries continue to innovate with the Industrial Internet of Things (IIoT) and the Artificial Intelligence of Things (AIoT) for vision-based applications. Notable examples include autonomous vehicles in warehousing and last-mile delivery, smart surveillance of critical infrastructure, tolling, traffic monitoring and access control in smart cities, parcel sorting and order fulfillment in logistics, real-time quality inspection on production lines, and medical imaging and assisted surgical robotics.

Each of these runs on computers that are expensive to visit and, in many cases, do not need to run around the clock. Machine vision systems on a production line, for example, may only need to run while the line runs. Remote power control turns them on before the shift, off after it, and back on remotely when a fault needs attention. The same applies to automated visual inspection cells built around GigE Vision cameras, where the computer, cameras and lighting all need to be ready together.

Shift-start wake-up

A line controller or MES can send magic packets to every inspection computer a few minutes before the shift, so models are loaded and cameras calibrated before the first product arrives. Where several cameras must capture in step, IEEE 1588 PTP time synchronization needs a few minutes to settle after power-on, which is another reason to wake systems early. An RTC wake set a little later acts as a backup if the network is down.

Staged boot to limit inrush

GPU-equipped vision computers draw a high current at power-on. Waking a whole line at once can trip a supply or a breaker shared with other equipment. Sending magic packets a few seconds apart staggers the start-up, which is easy with WoL and difficult with power-on after AC loss.

Sequencing cameras and sensors

Remote on/off also applies to the devices around the computer. A motion sensor and an IP camera can be arranged so that only one runs at a time: when an inspection fails, the sensor signals the failure, the camera is switched on to capture an image with its metadata, and the result is sent on for review. PoE cameras can be powered up and down from a managed PoE switch port, which saves power and network capacity on large systems and keeps idle cameras off the network. Our guide to PoE power budgeting covers sizing the switch for multi-camera systems.

Reducing bandwidth and lag

To conserve bandwidth, only the essential data should cross the network, with large or complex data processed near the device rather than in the cloud. Where many sensors and cameras share a network, switching off the ones not in use reduces traffic and lag, and lets the active systems use the capacity they need.

For vision and AI applications that need inference at the edge, a high-performance AI computer such as the Vecow EAC-5000 from Vecow hosts an NVIDIA Jetson Orin module, with the Jetson AGX Orin range rated at up to 275 TOPS, and includes 16-mode software ignition control for vehicle installations. Our automated food factory project shows fanless machine vision PCs inspecting products on the line, and our ALPR vision computers project shows an unattended vision system at a barrier.

These systems show the power features discussed above. We configure the BIOS power settings, Wake on LAN, watchdog and ignition delays to your specification, image the operating system and test the complete system before it ships, so every computer in a fleet starts and stops the same way.