Tunnel in Logisim — How to Connect Wires Without Crossing

A Tunnel lets you teleport a signal across your schematic without drawing long, overlapping wires. During netlist compilation, Logisim merges every Tunnel on the sheet that shares the exact same non-empty, case-sensitive Label into a single electrical net, just as if you had drawn an invisible copper wire between their pins.

To use a Tunnel, place one Tunnel at the source wire (for example, the output of a Clock or an Input Pin), set its Label attribute to a descriptive name such as CLK or BUS_A, and then place one or more matching Tunnels with the identical Label wherever that signal is needed.

Every Tunnel sharing a label must use the same Data Bits (width) attribute so the bus lines align bit-for-bit. Because Tunnels merge directly into one electrical net, only one active output should drive a given Tunnel network at a time; if two different gates drive 0 and 1 into Tunnels with the same label simultaneously, the entire named net turns red (E) from a short-circuit conflict.

Tip: Use Tunnels for global signals like CLK, RST, and multi-bit address buses so your combinational logic stays readable without wire clutter.