I've never had a use for pin pairs during several years of using PADS. All I know is that the pin pair definition seems to direct you to the closest pin while manually routing. Others may have more insight.
If you are trying to define the two nets that you listed in Layout without having a master schematic, go to ECO mode and then select 'add connection'. Select the pins on a net and press Enter to move onto the next net.
PADS' netlists are based on pin pairs, and is why you cannot have single pin nets.
A pin pair is just a single connection between two pins.
A net is one or more pin pairs.
When you add connections, you're adding pin pairs.
Nets have names that can be changed by the user, but pin pairs are only named with the format of RefDes.PinNumber, like U1.1-R1.1.
You can create design rules for selected pin pairs different from the whole net, which is very useful for designs using say, current sense lines, or matched length routing for DDR memory.
For nets with multiple pins, the routing order can be fixed in Design Rules using Routing Toplogy, and setting it to Protected. As an example, this is useful for clock nets that are not allowed to branch, and require a terminator at the end of the route.
That's interesting. I can see the pin-pair rules coming in handy when I have a wide high current trace and want to connect a sense line to it that doesn't need to be wide. You say the routing order can be fixed, so I interpret that as locked. Is there a way to change the routing order without manually regenerating the net in ECO mode?
By 'in Design Rules using Routing Toplogy' do you mean <Setup><Design Rules>(Net)$$$xxx then the Topology section of the Routing tab in Layout, or is that somewhere else (in Router)?
There's two ways to change the pin pair order manually, and they use the connections (ratsnest). This assumes the existing nets have the minimized topology.
This works for Layout and Router.
Simply move the parts until the connections are in the order you want.
You might have to manually Minimize (Ctrl-M) the nets.
Select the nets of concern.
Select Properties with a right-click.
Select Rules, Routing.
Set Toplogy to Protected.
Now move the parts back into place, and the pin pair order won't change.
In Router only, there's a Reschedule command.
If there's routing on the net, this command either doesn't work well or sometimes it won't work at all.
Select the Connection close to the pin you want to change.
Right click, and select Reschedule.
The connection will attach to the cursor, and the available pins for the new pin pair location will highlight.
Select the desired location. Repeat as necessary until the order is how you want.
This command will automatically set the topology to Protected.
If a net is half of a differential pair, the other half will change automatically, which could be undesireable if it wasn't exactly the same as the half you're changing. In that case, you need to break the diff. pair up, move the connections, then re-pair it.
Thanks. That first method is cryptic but fits in with the PADS. I'll try that next time I need this.
We now return this thread tot he originally schedule topic.