altiumpcb
I have difficulties to understand what are the differences between a net, a port and a off sheet connector.
I particularly don't understand when to use a port and when to use a off sheet connector when there are multiple sheet.
I see sometimes people use port and sometimes they use off sheet connector, while I still read that only net can be used in some situations.
Can you post your sub-sheets?
From looking at what you have posted, I think you may have a typo in the entry: RB[0..7]. You typically get the red line below the entry when it is not correctly tied to a port on the child-sheet.
Right-click on the sheet symbol, and select "Sheet Symbol Actions" -> "Synchronize Sheet Entries and Ports"
Anyways,
I created a simple, minimal test schematic to do what you are doing:
Top Sheet:
Sheet 1:
Sheet 2:
Project Hierarchy:
And it properly connected the nets across the different schematics:
For what it's worth, I am fairly sure you have to both name the buses with net-labels on each child-sheet, and name the ports.
Also, the bus name and wire names have to have the same prefix:
For example, a set of wires HERP0 HERP1 HERP2 HERP3 HERP4 has to be in a bus named HERP[0..4]. It may also have to be zero-indexed (i.e. start at 0, rather then 1), but I'm not totally positive on that.
Also, I do indeed get the "Net NetName has multiple names" warning, but it's just that, a warning. You can turn the warning off, or just ignore it. I tend to leave it on, and before I have a board produces, go through all the warnings and make sure that I intend for whatever they refer to to be that way.
The best way to do this in Altium is to use Net Ties. These will join two separate nets. See: https://www.smtnet.com/library/files/upload/NetTies-and-How-to-Use-Them.pdf
I will also occasionally use zero-ohm resistors to accomplish the same goal if there is a chance that I may need to break the connection to help troubleshoot an issue.
Best Answer
A net is a connection name. If you have a signal on one side of your schematic with a net name of "SIG_A" and you have another net name of "SIG_A" on the other side. Those two nets are connected. It's as if there is a wire that ties them together. Nets tend to be local to a schematic (unless you are using a power net - which MAY be global).
An offsheet connector allows connections to be made horizontally. What this means is if you have a large design that can't fit into one page cleanly, you can use off sheet connectors to "continue" your signals to another sheet (but on the same level). It's almost like an extension of the same sheet.
Ports allows connectors to be made vertically. What this means is that you can create sheet symbols that represent your sheet, and connect them together via ports.
I tend to use a multi hierarchical design because allows me to see how circuit sections or typologies are connected together and so I tend to favor ports. But on large designs, I use off-sheet connectors as well.