Your rack is 60 m away from the display, the HDMI cable will not reach, and there is a Cat6 run already in the wall between the two points. A search for an “ethernet to hdmi adapter” turns up a thumb-drive-sized plug that claims to do the job from a single network jack, and a box with an RJ45 input and an HDMI output that looks like the real answer. Knowing which one is which decides whether the screen lights up. This article covers the display-side receiver – the RX unit – of an HDMI-over-Ethernet pair: what it does with the run, how it pairs with the transmitter, and why it cannot be replaced by a bare plug.
Quick answer:
Buy a matched TX and RX pair, not a single adapter. The RX unit sits at the display, takes the Cat5e or Cat6 run into its RJ45 input, and outputs HDMI to the screen; the TX unit sits at the source and does the reverse. Both ends usually need 5V power. Passive baluns reach roughly 30 m at 1080p, powered and HDBaseT-class units reach 50-100 m at 4K. One pair feeds one display, TX and RX cannot be swapped, and a lone plug on a live network jack will not decode network traffic into video.
Ethernet to HDMI Adapter: How the RX Unit Delivers Video Over a Network Cable
What the Display-Side RX Unit Actually Does
In an HDMI-over-Ethernet link, the box next to the display is the receiver, or RX unit. It has an RJ45 input that accepts the network cable coming from the source rack, and an HDMI output that feeds the TV, monitor, projector, or video wall processor. Its job is narrow and specific: convert the balanced, packetized signal arriving on the twisted pairs back into a standard HDMI stream that the display can lock onto. It is not a network device in the usual sense. It does not request an IP address, it will not appear in a router’s client list, and it does not decode streaming, IPTV, or web traffic. It simply reverses what the transmitter unit did at the far end, and it does so on a dedicated run rather than on a shared LAN segment.
Why a Bare “Ethernet to HDMI” Plug Cannot Decode Network Video
A passive plug the size of a thumb drive cannot turn ordinary Ethernet traffic into HDMI video, and buyers should be skeptical of any listing that suggests otherwise. Standard network frames from a switch, router, or internet feed carry no HDMI payload, no pixel clock, and no HDCP session, so there is nothing for a small passive part to convert. When such a product is legitimate, what it really is is one half of a balun pair – it carries an already modulated HDMI-over-twisted-pair signal between the two halves of the same kit. That is also why a lone RX cannot be dropped onto an existing building network and expected to work, and why a wall port that feeds a network switch will never show a picture on a monitor at the other end, however well the cable is terminated.
Pairing and Orientation: Transmitter at the Source, Receiver at the Display
The most common installation failure with these kits is a reversed pair. The TX unit must sit at the source device – media player, PC, set-top box, or switcher output – and the RX unit must sit at the display. They are not interchangeable, and both housings are normally labeled. Reverse them and the link will not establish, no matter how good the cable is. There is a directional rule inside each unit as well: the HDMI port on the TX is an input, and the HDMI port on the RX is an output. Feeding a source into the HDMI port of an RX unit is a frequent mistake when an installer assumes the box is a two-way adapter. Treat the pair as a one-way pipeline with a defined head and a defined tail, and order the receiver as the exact partner of the transmitter you have – the same series, from the same supplier. If you also need the source-side half, the matching HDMI to Ethernet adapter covers the transmit end of the same link, and a complete HDMI extender adapter kit ships both boxes with their cables and power leads.
Power at the RX End Is Not Optional
Almost every balun pair and powered extender in this class takes external power at both ends, typically 5V over USB from a nearby USB port, a power supply brick, or a USB outlet in the display’s service loop. The RX unit is the one installers most often leave unpowered, because the display side already has an HDMI connection and looks finished. An unpowered receiver is the first cause of a dead screen, and it is worth checking before anything else. Confirm that the power indicator on the RX is lit and that the 5V lead is seated at the receiver rather than dangling behind the TV. Some HDBaseT-class receivers accept power over the link from the transmitter, but that is model-specific – check the datasheet rather than assuming it.
EDID and Handshake on the Display Side
EDID is the display’s capability report. During link setup the RX unit reads the display’s EDID and passes it back toward the TX unit, so the source advertises a format the far end can actually accept. Problems appear when the source is already running before the display is powered – a common scenario with a media player that boots faster than a projector. The source reads empty or stale EDID, decides the sink cannot be trusted, and outputs nothing. The fix is a defined power-up order: display first, then RX, then TX, then source. If the screen goes black with an “out of range” or “no signal” message, cycle the RX and the display while the source stays up. Many receivers include an EDID copy or memory switch for exactly this reason; use it when a display wakes slowly or when two sources share one screen through a switcher.
Distance Classes Over Cat5e and Cat6
Reach depends on the class of the extender rather than on the cable alone, so plan from the envelope below and leave headroom for joins, temperature, and cable quality. These are engineering classes, not guarantees.
| Extender class | Typical cable | Resolution | Planning reach | Power required |
|---|---|---|---|---|
| Passive balun pair | Cat5e | 1080p | Roughly 30 m | Recommended at both ends |
| Passive balun pair | Cat6 | 1080p | Roughly 30 m, more stable | Recommended at both ends |
| Powered extender | Cat6 | 4K | Up to 50-100 m | Required at both ends |
| HDBaseT-class extender | Cat6 or Cat6a | 4K | Up to 100 m | Required, one or both ends |
Cat6 holds a more stable link than Cat5e at the same class because of its tighter twist and better crosstalk performance, and a HDMI to Cat6 converter pair is the usual choice for new structured cabling. Patch panels, couplers, keystone jacks, and wall plates all add insertion loss, so keep the run as continuous as you can and avoid chaining two short cables through a barrel coupler. A cable tester that reports length and pair continuity is far more useful on this job than a bandwidth test, because the extender cares about the physical pairs, not about IP throughput. Latency on a balun pair is small but nonzero, which is fine for informational displays, digital signage, and control-room walls, and not something to quote for competitive gaming.
Questions Buyers Ask Before Ordering
How many displays does one receiver feed? One RX unit feeds one display. To drive several screens from a single source, split the HDMI before the transmitter and give each screen its own TX and RX pair. Can I buy only the RX as a spare? Only if it is the exact partner of your existing TX; a mismatched receiver from another family will not negotiate. Does the run have to be dedicated? Yes. The pair needs an end-to-end cable between the two units, not two patch cords into a switch. Will it pass 4K and HDCP? At the powered and HDBaseT-class tiers, yes, within the stated reach; at the passive tier, plan for 1080p.
Three Deployment Scenarios
- Retail signage refresh: a media player in a back-office rack feeds four in-window screens over existing Cat6. Each screen gets its own TX and RX pair, the receivers sit behind the displays on 5V USB, and the runs stay continuous from rack to wall plate.
- Meeting room with a ceiling projector: a table box holds the source, the TX sits in the credenza, and the RX mounts at the projector. Because the projector wakes slowly, the receiver’s EDID copy mode is enabled and the power-up order is display, RX, TX, source.
- Warehouse control room: a single monitoring PC drives a large display 70 m away through a powered HDBaseT-class pair. The receiver takes power at the display end, the run is unbroken Cat6, and no patch panel is inserted between the two units.
Setup and Troubleshooting Checklist
- Confirm you have a matched TX and RX pair from the same series, and that the TX is at the source and the RX is at the display.
- Verify the HDMI output of the RX goes to a display input, not to another source, and that the RJ45 input takes the run from the TX.
- Power both units, usually 5V USB at each end, and confirm the link and power LEDs at the receiver.
- Check the run: continuous Cat5e or Cat6, no barrel couplers, correct pinout, and a tester confirmed continuity and length.
- Boot in order – display, RX, TX, source – then set the resolution on the source to a mode the display supports.
- If there is still no picture, cycle the RX and the display with the source running, and engage EDID copy or memory mode on the receiver.
- Test with a short known-good patch cable between TX and RX to separate a cable fault from a unit fault before replacing hardware.
Treat the receiver as the display-side endpoint of a dedicated link, and most of the failures attributed to an “ethernet to HDMI adapter” disappear: matched pair, correct orientation, power at both ends, one continuous cable, and a boot order that lets EDID travel back to the source.
FAQ
1. Can a single ethernet to HDMI adapter work without a matching transmitter?
No. Consumer HDMI-to-RJ45 products are balun pairs: one TX unit at the source and one RX unit at the display. The receiver carries an already modulated HDMI signal that only its matching transmitter produces, so a lone unit on a live network jack has nothing to convert. Always order the complete matched pair from the same series.
2. Do both the TX and RX units need power?
In most balun pairs, yes. Both ends usually take 5V over USB from a nearby port or power supply. The receiver is the end installers most often leave unpowered, and an unpowered RX is the leading cause of a dead screen. Some HDBaseT-class models accept power from the transmitter, but that is model-specific, so confirm it on the datasheet.
3. How far can an HDMI-over-Ethernet pair run over Cat5e or Cat6?
Distance depends on the extender class. Passive baluns reach roughly 30 m at 1080p, while powered and HDBaseT-class extenders reach up to 50-100 m at 4K. Cat6 holds a more stable link than Cat5e at the same class. Treat these figures as planning classes rather than guarantees, and keep patch panels or couplers out of the run.
4. What causes a black screen when the source boots before the display?
The source may read empty or stale EDID and stop outputting. Power up in the order display, RX, TX, source, so the receiver can read the display’s capability report and pass it back. If the screen is still black, cycle the RX and the display while the source keeps running, and enable EDID copy mode on the receiver.
5. Can one receiver feed more than one display?
No. One RX unit feeds one display. For multiple screens, split the HDMI before the transmitter and give each display its own TX and RX pair, or use a splitter with a balun system. Each pair then needs its own dedicated cable run from the rack to that display, without a network switch in between.