Luna Display and Adapters
Can Luna be used with an adapter, hub, or dock?
Your Luna Display unit should be plugged in directly to a compatible port on your Mac or Windows PC. Not every adapter uses the same communication protocols as the Luna Display hardware, so we cannot guarantee that Luna will work with every adapter, hub, or dock setup. Using Luna with any adapters, hubs, or docks would be at your own discretion, as we cannot guarantee compatibility since they are not officially supported.
Adapters may be compatible with wired connections (Ethernet or Thunderbolt) cables since wired connections are not related to our Luna Display hardware.
Can adapters be used for wired connections between devices?
Yes, adapters can be used for wired connections, such as Thunderbolt or Ethernet cables. This is recommended if your devices have incompatible port types. Using adapters for wired connections is different than using an adapter to plug your Luna unit into your computer. You will still need to plug the Luna Display hardware directly into your Mac or PC, even if you are using a wired connection.
For example, let's say you are using a 2015 iMac as a secondary display for your 2021 MacBook Pro and would like to use a Thunderbolt cable to connect your devices (instead of using WiFi). The 2015 iMac has Thunderbolt 2 ports (mini DisplayPort), while the 2021 MacBook Pro has Thunderbolt 4 ports (USB-C). You will need an adapter in order to use a Thunderbolt cable between these devices. In this instance, we would recommend using a Thunderbolt 3 to Thunderbolt 2 adapter with a Thunderbolt 2 cable.
In another example, using the same devices as above, let's say you'd rather use an Ethernet connection between these devices. The 2021 MacBook Pro does not have an Ethernet port, while the 2015 iMac does. You would need an Ethernet to USB-C adapter in order to utilize an Ethernet connection between these two devices.
What about adapters on M1 Macs?
We recently did some testing with USB-C adapters on M1 Macs and found that the same adapters that worked on Intel-chip Macs did not work on M1 Macs. After a bit of research, we discovered that the API we need to use Mini DisplayPort on M1 Macs is not yet available. It is possible that Apple could add this in the future, but for now, this, unfortunately, may not work.
Mini DisplayPort Luna
Thunderbolt and Thunderbolt 2 are typically backward compatible and can accept both Thunderbolt and Mini DisplayPort (mDP) protocols. Luna uses mDP protocol so it is compatible with Thunderbolt, Thunderbolt 2, and mDP ports.
Certain adapters, like Apple's Thunderbolt 3 to Thunderbolt 2 adapter, are not compatible with the mDP protocol (which is what mDP Luna uses), even though Thunderbolt 2 protocol is able to support mDP protocol.
From Apple's support article about Apple's Thunderbolt 3 to Thunderbolt 2 adapter:
The mDP Luna is not a Thunderbolt display, although Thunderbolt (and Thunderbolt 2) and mDP have the same shape. The mDP Luna only supports mDP and DisplayPort protocol. Thunderbolt support for Luna is not on our immediate roadmap.
In the same way that not all USB-C ports can support displays, not all USB-C adapters will be compatible with Luna and other displays. The USB-C Luna uses DisplayPort Alt Mode. Not all USB-C ports and adapters support DisplayPort Alt Mode (a type of DisplayPort protocol) as this is an optional feature.
What is DisplayPort Alt Mode?
DisplayPort Alt Mode is a type of Alternate Mode (Alt Mode), which allows USB-C ports to transfer data and video using different protocols, like DisplayPort. The USB-C Luna uses DisplayPort Alt Mode, so it will need a port that supports this same protocol.
USB-C Port Types
What about a DisplayPort to HDMI adapter?
DisplayPort signals are typically not compatible with HDMI, though this may also depend if the port output supports single-mode or dual-mode DisplayPort protocol.
If the port supports dual-mode DisplayPort (also known as DP++), this means the port has the ability to adjust its signal to match HDMI signals, and you might be able to use a passive adapter or cable. If the port does not support dual-mode DisplayPort, then you would need to use an active adapter or cable to perform the signal conversion.
This is not something we have tested extensively, so it is not recommended.