From StarMade Wiki

One of the key mechanics of setting up systems in StarMade is linking: connecting system modules either directly to a Ship Core, to a relevant controller/computer block, or to other blocks in a mechanism.

Linkable Systems

Systems which can be linked include:

Linking Controls

Linking is achieved, either in Build Mode or Astronaut Mode, by aiming at a controller and pressing C, then aiming at the related module(s) to be linked and pressing V. When in Build Mode, multiple modules in a physically-contiguous group may be connected all at once by aiming at part of the group and pressing Left Shift + V.

Most system controllers can only be linked to their related module type: for example, a Cannon Computer can only be linked to Cannon Barrels.

When a controller is selected, it will be highlighted by a pulsing orange outline around the block, and all modules connected to it will be highlighted by pulsing purple outlines.

Linking Secondary and Tertiary Systems

Most Support Tool Systems can have secondary systems which modify their effect, and all Weapon Systems can have both secondary and tertiary systems linked, allowing even greater modification of their nature. In both cases, these additional systems are added by selecting the primary system's computer, and then connecting it to another system computer. Both the secondary and tertiary system computers must be linked to the primary.

Alternatively, secondary and tertiary systems can be linked in the Weapon Menu. This is accessed by pressing G. Once the Weapon Menu is open, the icons of the desired secondary or tertiary systems can be dragged and dropped into the "Secondary" or "Tertiary" columns in the desired primary system's row.