Partial Routing with constraints from Allegro PCB

 Here is an update:

 I was not able to create a NULL layer set, if the traces did not have a layer, the were routed on all layers anyway (Is there a way to stop this?), but I created a Dummy layer and forced everything except for my desired routes onto this layer.  This appears to have the desired effect.

 What I did found that after I routed and imported the session back into Allegro PCB, my routes did not follow the Relative Delay rules.  After restarting Specctra with a Route Custom, I found that many of my Matched Groups in Allegro Constraints and not getting loaded into Specctra.  I verified that they are in the DO file.  It is odd because there are identically defined groups (with different nets).  Some are added, others are not.

 Any ideas?

 I'm not sure if layer sets are supported under perf_L license.  The easiest way to try?

Start "Route Interactive"

Once you see the board load you will see a list of warnings (if any).

Just for fun, type in at the command line "route 50".  Do you get a pop-up box warning you of license related issues?

If you quit (and save), the routes will load automatically back into Allegro.

It should have picked up your matched groups but it may have routed more than you wanted.

So, try it again (fresh, save the unrouted board to learn how all this works).  Now, route interactive again.

This time at the command line type in "select group XXX" where XXX is the name of one your matched groups.  You can continue to enter "select group YYY" to keep adding groups to be routed.   When you 'select', the router will only route the selected nets and leave the others alone.

You can also "unselect" the same way. You can select through the menu as well.

There is a 'smart' router in the route menu.  I prefer the standard router but you need to learn a little bit about the setup needed prior to routing.  Costing is an important feature of the router.

HTH