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Power over Ethernet (PoE) and LabJack

February 28, 2018

Power over Ethernet (PoE) standards celebrates 15 years of official adoption by IEEE 802.3af in 2018, and is just as relevant today as ever. Mainstream adoption of PoE devices has driven down costs of switches, splitters and injectors combined with an exploding number of PoE capable/compatible devices. This has offered expanded opportunities to not only established industrial processes but also experiments, prototypes and projects on a shoestring budget.

PoE offers innovators a variety of creative applications to the world of data acquisition (DAQ). Recently, LabJack performed thorough product testing to better serve those clients wishing to utilize PoE for their upcoming deployments. Using one of a variety of inexpensive splitters/adapters our Ethernet capable LabJacks (T7 family, T4, & UE9 Family) can be used with PoE, eliminating the need for nearby AC power. Using Cat 6 cable, PoE can reliably transmit power and data 100 meters/328 feet. The benefits of PoE are already well documented. LabJack has tested 3rd party switches, injectors and splitters in conjunction with LabJacks so you can incorporate PoE into your next LabJack project with confidence.

Consider using PoE the next time you deploy a LabJack in a remote setting that is without convenient AC power such as: factories, warehouses, outbuildings, outdoors, underground, other farming/agriculture applications, and other distributed data collection and automation applications.

LabJack PoE Testing Notes:

We recently tested a number of different injectors and splitters to confirm that noise on grounded AIN0 stayed around 1-2 µV with Range=0.1 and Resolution Index=Auto=9. On all tested PoE equipment, noise was within this limit. All our LabJack devices have excellent power supply rejection and thus analog input readings are generally not noticeably affected by noise and instability of the supply voltage.

3rd Party PoE Devices Tested:

Switches:

Injectors:

All injectors were tested with the WT-AF-USB splitter, and some injectors were tested with other splitters.

All devices performed without errors or excessive noise.

Splitters:

Many of these splitters seemed to have auto power shutdown. They might take a few seconds to power up, and might not power up at all if the load (T7) is not connected.

All tested splitters had one of the following connectors for power output and we used the listed cables to connect to a T7-Pro:

Female Barrel 5.5 x 2.1: Tensility 10-00240 and Tensility 10-00648
Male Barrel 5.5 x 2.1: Amazon B00QHL2PTA and Belkin F3U133-06INCH
Female Type A USB: Belkin F3U133-06INCH

The first 2 tested splitters have a switch to select 5V, 9V, or 12V output:

TP-Link TL-POE10R, female barrel power output.
TRENDnet TPE-112GS, female barrel output and also includes a cable to provide male barrel output.

They have no other indication of what output voltage is selected. If you use one of these splitters, be sure to keep the switch in the 5V position to avoid damaging a LabJack device. All LabJack devices require a 5V power supply.

The next 2 tested splitters also have a voltage switch, but also have an LED indicator—this makes it easier to ensure 5V is selected:

TRENDnet TPE-104S, female barrel power output.
Amcrest Splitter, Amazon B00CDT7KPO. Female barrel output and also includes a cable to provide male barrel output.

The last tested splitter has fixed 5V output and also is available in the following specific model that includes a female USB connector. This seems to be a great splitter: