Getting started with OAK PoE devices

We currently have two Power-over-Ethernet (PoE) devices:

PoE allows a single Cat5e (or higher) Ethernet cable to be used to both power a device and give it connectivity at 1,000 Mbps (1 Gbps) full-duplex at up to 100 meters (328 feet).

https://user-images.githubusercontent.com/18037362/125928421-daed2432-73fb-4c5b-843e-037c7383a871.gif

After connecting the PoE device, the Ethernet connectivity LED (shown above) should turn on and start occasionally flashing.

Step by step tutorial

  1. You will need a PoE switch or Injector to power the PoE device. Click here for the full tutorial. After powering the device, LED should start blinking, as on the GIF above.

  2. Connect your computer to the same LAN as the PoE device

  3. Make sure you have depthai version 2.7.0.0 or newer. You can update your depthai python package with python3 -m pip install depthai>=2.7.0.0

  4. Now you can run any code sample / depthai experiment / depthai_demo as you would when connecting a DepthAI device with a USB-C cable!

../../../_images/poe-working.jpeg

After these steps, the depthai_demo is working on the OAK-D-POE!

How it works

When your program tried to create the device (with dai.Device(pipeline) as device:), the library will search for available devices that are connected either by USB port or on the LAN. It searches for PoE devices on the same network (eg. LAN) and communicates over TCP protocol. That way PoE devices work in same manner as USB devices. As with theUSB-C connection, you can specify the Mx ID to specify to which DepthAI PoE device you would want to connect to (more info here).

PoE Troubleshooting

  • DHCP and Static IP

    By default, PoE devices will try to pull an IP address from DHCP. If a DHCP server isn’t available on the network, devices will fall back to static IP 169.254.1.222. In this static fall-back case, your computer will need to be in the same range. This can be achieved by setting a static IP on your computer (e.g. with static IP: 169.254.1.10 and netmask: 255.255.0.0).

  • Ports and Firewall

    UDP Device discovery is handled on port 11491, and TCP XLink connection is handled on port 11490.

    On Ubuntu by default the firewall is disabled, so you shouldn’t have any issues. You can check this though by executing the following command:

    > sudo ufw status
    Status: inactive
    

    If you have your firewall enabled, you might need to allow these two ports:

    sudo ufw allow 11490/tcp
    sudo ufw allow 11491/udp
    
  • VPN connection

    VPN connectivity could also disrupt the connection with the PoE device (as your computer may be searching only the remote network for the device, so would be unable to discover it on the local network), so we suggest turning the VPN off when using the PoE devices or otherwise ensuring that your local routing is setup such that local devices are usable/discoveragle while VPN connectivity is active.

  • Connected to the same LAN via 2 interfaces (WiFi/ethernet)

    We have seen that in some rare circumstances when your host computer is connected to the same LAN, it can happen that device discovery finds the same POE device twice, so it will print the IP address of that device 2 times. In some rare occasions this can lead to an error (we have seen this when using multiple devices) on initialization; RuntimeError: Failed to find device after booting, error message: X_LINK_DEVICE_NOT_FOUND. We will try to fix this bug as soon as possible. Workaround solution: disconnect from one of the interfaces; so disconnecting (from the) WiFi should resolve this issue.

  • Insufficient power supply
    If your PoE device does not work, or in some rare cases, it works for a period of time and then suddenly stops working, there might be an issue with your PoE switch. For example when the power budget per port seems to be sufficient, but the overall power budget for the switch is being exceeded due to demands from devices on other ports.

    It is worth checking the specifications of your PoE switch / injector with respect to its overall power budget.

Manually specify device IP

In case you are able to ping the device but the autodiscovery doesn’t work (eg. device itself isn’t in the same LAN), you can manually specify the IP address of the POE device.

import cv2
import depthai as dai

pipeline = dai.Pipeline()

camRgb = pipeline.createColorCamera()

xoutRgb = pipeline.createXLinkOut()
xoutRgb.setStreamName("rgb")
camRgb.preview.link(xoutRgb.input)

device_info = dai.DeviceInfo()
device_info.state = dai.XLinkDeviceState.X_LINK_BOOTLOADER
device_info.desc.protocol = dai.XLinkProtocol.X_LINK_TCP_IP
device_info.desc.name = "169.254.1.222"

with dai.Device(pipeline, device_info) as device:
    qRgb = device.getOutputQueue(name="rgb", maxSize=4, blocking=False)
    while True:
        cv2.imshow("rgb", qRgb.get().getCvFrame())
        if cv2.waitKey(1) == ord('q'):
            break

Got questions?

We’re always happy to help with code or other questions you might have.