In Capture, you can establish connectivity with wires or aliases.
Two perpendicular wires or buses are connected if:
- They form a "T" intersection, either by dragging an object or placing a wire.
- A junction is placed where they cross.
If they simply cross at 90 degrees, they are not electrically connected unless you place a junction at the intersection manually.
You can also use an alias to connect a signal from one area of your schematic page to another. For example, suppose you have placed a part on your schematic page and you want to connect it to another part at the opposite corner of the schematic page. Instead of drawing a wire from the first part to the second part, you can assign a single net alias to a wire connected to both parts. You can connect two crossing nets, after they have been placed, by placing a junction where they cross. For more information about placing junctions see Placing junctions.
A net can have any number of aliases plus one optional net name. The only purpose of the net name is to give the highest priority to one of a net's aliases. When you assign a name to a net, you force Capture to resolve netname conflicts in favor of a particular alias.
As you place buses and wires:
- A bus and a wire can be connected only by name.
If you begin or end a bus segment on a segment of a wire, a vertex is added to the wire and a junction appears, but the bus and wire are not electrically connected.
If you begin or end a wire segment on a segment of a bus, a vertex is added to the bus and a junction appears, but the wire and bus are not electrically connected. - Two buses or two wires can be connected physically.
If you begin or end a bus segment on a segment of another bus, a vertex is added to the second bus, and a junction appears—the buses are connected.
If you begin or end a wire segment on a segment of another wire, a vertex is added to the second wire, and a junction appears—the wires are connected.
If you place parts so that two pins meet end to end, the pins are connected.
OrCAD recommends that you connect the pins of the parts using a wire, and avoid placing parts so that two pins meet end to end. This is because, parts with direct pin-to-pin connections produce a system generated net name to establish the connection and:
- Capture will not allow you to assign your own net name in the place of the system generated net name.
- Searching for the system generated net name can be difficult if you are not aware of the pin-to-pin connection.
- If you move the parts after creating the netlist, the system generated net name might change. This may cause net name conflicts when you run back-annotation.
Capture preserves the case of part names and net names, but ignores the case when comparing names for electrical connections. That means you may use upper-case or lower-case letters as you wish, but you need not remember the case.