Powering Unipi PLCs through PoE

This tutorial describes the connection of Unipi controllers using 802.3at PoE+ splitter. This connection is useful especially if you need to place the PLC in locations lacking a conventional ~230V socket (ie. sensor stations). This tutorial will show you how to power the Unipi over Ethernet cable while retaining local network connectivity.

Components used in the tutorial
  • Cat6 network cable (RJ45)
  • conductor (Cu, 0.5mm2)
  • Planet IPOE-162S PoE splitter
  • Planet GSD-908HP network switch
    • The switch used is just one of possible variants. You can use any 802.3at PoE+ compliant network switch.
  • Unipi Axon PLC

Connection example

Planet IPOE-162S
  1. set the splitter for 24V voltage using the onboard switch
  2. connect the splitter’s V+ clamp to the PLC’s 24V clamp
  3. connect the splitter’s V- clamp to the PLC’s GND clamp
  4. using the network cable, connect the splitter’s Data Out port with the PLC’s ETH port
  5. plug an 802.3at PoE+ compatible network cable into the splitter‘s PoE In port
Planet GSD-908HP
  1. use one of the switch ports to connect it with the PoE In port on the splitter via a suitable network cable
  2. repeat the step for any other additional splitter
  3. connect the WAN network cable into the port 9

Technical data

Using a single splitter to power multiple PLCs is not recommended!




Calculating the maximum load – examples

The calculations below are applicable for GSD-908HP PoE+ switch and IPOE-162S PoE+ splitter.

1) Maximum number of connected Unipi Neuron L403 controllers
  1. maximum load of the Neuron L403 = 25W
  2. maximum load of the splitter = 25W
    • 25W – 24W = 1W
    • the resulting value is a positive number = suitable
  3. maximum load of the switch = 100W
    • 100W ⁄ 24W = 4,166

Based on these calculations, we can safely use 4 PoE+ powered Neuron L403's

2) Maximum number of connected Unipi Axon S105
  1. maximum load of the Axon S105 = 25W
  2. maximum load of the splitter = 25W
    • 25W – 12W = 13W
    • the resulting value is a positive number = suitable
  3. maximum load of the switch = 100W
    • 100W ⁄ 12W = 8,333

Based on these calculations, we can safely use 8 PoE+ powered Axon S105's

3) Various combinations of Unipi models
  1. maximum power input:
    • Axon L205 → 19,5W (1x)
    • Axon M205 → 16W (2x)
    • Axon S105 → 12W (remaining)
  2. maximum load of the splitter = 25W
    • 25W – 12W = 13W
    • 25W – 16W = 9W
    • 25W – 19.5W = 5.5W
    • the resulting value is a positive number = suitable
  3. maximum load of the switch = 100W
    • 100W – 19,5W – 2x16W = 48.5W
    • The remaining: 48.5W ⁄ 12W = 4.041

Based on these calculations, a single switch can power 1× Axon L205, 2× Axon M205 and 4× Axon S105