minimizing tracks on one layer, maximizing on the other

In the meantime, it seems I found one solution. I don't know exactly how it works but it is like this - first I start automatic routing by activating the Route/PCBrouter/RouteAutomatic, Strategy=UserSmartRouter, and check the option for Bottom layer so only bottom layer will be routed on.

When it finishes work, I have most connections on bottom layer with the unconnected (read: hard to route) rats ready to be routed say manually on the Top layer.

Hi,

I can think of the below way.Hope it helps.

Suppose you have more connections running horizontally, then you can limit the routing on the preffered layer using layer direction and Tax assignment. For the other secondary layer don't give any routing preference or give that direction which is opposite to the preferred layer direction..

Hello,

I believe adding costing to the layers will get what you are looking for but you need to open up the Allegro PCB Router GUI.

In Allegro open up the Allegro PCB Router, Click Route > PCB Router > Route Editor (Allegro window will disappear and the Allegro PCB Router will appear)

In Allegro PCB Router do the following:

• Click Rules > Layers > Costing... 
• Select the Cost Value, Layer name and click Apply. 
• Click Autoroute > Route... either select Basic or Smart then click Apply.

You will need to play with the different Cost Values to get the desired effect.   This setting is only good for this session of Allegro PCB Router and as far as I know there is no way to set this in Allegro so it passes to the router.  You could execute a do file in the Allegro PCB Router but using the GUI is just as easy.  Here is an example of what the do file would look like:

cost layer <subclass name> high
cost layer <subclass name> low

You can load the do file using File > Execute Do File..

When you are finished routing Click File > Write > Session...  then File > Quit.. to Exit Allegro PCB Router which will then open Allegro.  Give it a try and see what you think.

Hope this helps,
Mike Catrambone
Plexus Engineering Solutions

 Well Mike, thank you so much for your detailed and instructive answer. It helped a lot  (first time in Allegro Router doing anything) and all is as you said. Also found the additional option for no via routing that I was using in Spectra (in Allegro Router it seems to be Rules/pcb/wiring/general limitVias=0), and all works beautifully. I think I shall love this Allegro thing...

It's a pitty there is no ready to use export back to Allegro: it seems both routers are mighty and combining both could probably been even more powerful.

slavne said:

 It's a pitty there is no ready to use export back to Allegro: it seems both routers are mighty and combining both could probably been even more powerful.

This does not make any sense.  There is only one router and it's set up to export into Allegro seamlessly...what problems did you encounter?