Relay

The Relay is a versatile signal processing component that receives an input signal, applies a configurable logic operation, and passes the result to connected buildings or components. Unlike the dedicated AND, OR, and NOT Gates, the Relay can be configured to perform any of several operations including NOT, AND, OR, XOR, and Passthrough. This flexibility makes it one of the most useful automation components in the game, despite costing only 300 Science Points to unlock.

In Passthrough mode, the Relay simply forwards its input signal without modification, which is useful for extending signal range or creating labeled junction points in complex circuits. The logic operation modes (NOT, AND, OR, XOR) allow the Relay to function as any of the dedicated logic gates, though it can handle only the operations applicable to its input count. For two-input operations, the Relay needs two signal sources connected. The XOR mode is particularly notable because there is no dedicated XOR Gate component; the Relay is the only way to achieve exclusive-or logic natively.

Relays serve as the backbone of well-organized automation networks. Use them as labeled signal hubs to name and describe what each signal path does, making your circuits easier to understand and debug. A common pattern is to place Relays at key decision points in your automation layout, clearly labeling each one with its purpose (such as 'Drought Emergency' or 'Low Food Alert'). Relays can also chain together to create multi-stage signal processing, passing signals through several operations before reaching their final destination. For most automation projects, a healthy stock of Relays is more valuable than dedicated logic gates, since a single Relay type can replace any gate while also providing passthrough and XOR capabilities.