The Upgrade Multiplexer is a machine used in conjunction with an Industrial Tesla Coil.
Upgrade Multiplexers can be used as a target for any of the various Industrial Tesla Coil upgrades (Tesla Range Upgrade, Tesla Speed Upgrade, Wavelength Shift Upgrade, and EMP Upgrade) as well as other Upgrade Multiplexers. This allows you to chain together as many as you want to maximize your Industrial Tesla Coil.
The Upgrade Multiplexer, like all other machines added by this mod, will emit a beam of light in the direction it is placed. When aimed at another Multiplexer or Industrial Tesla Coil it will pass on all the upgrades currently aimed at IT.
Each Multiplexer thus has 5 input sides (where other mulitplexers or upgrades can beam into it) and 1 output side where its own beam will emit.
Use caution when eagerly applying these to your Industrial Tesla Coil. Inadvertently parking a supremely range upgraded coil on top of a cave network can result in a massive power drain as well as a ton of floating mob items.
Also note that it cannot multiplex filter settings, only upgrades.