how can i select the length of a trace in Ultiboard?

[Beboni007]

Hello
i got a problem with the length of some traces.
Some special traces need to get the same length.
I used the group edit item to create a grout with the needed nets.
How can i creat the traces now. When i use the item Follow-me it doesn't apply the selected value.
At least i tryed to use the Autoroute function but this just function doesn't work. (Error during autorouter preprocessing. Source: Autorouter Parameter Error)
Is there any smart possibility to handle the problem?
Best regards

[_user32]

Beboni007,

Here is how matched length traces can be completed in Ultiboard.

First you do not necessarily need to setup a part group to do this... (differential pairs would require grouping)

1. Forward annotate your schematic / netlist from Multisim.

2. Determine the absolute minimum routing length from the origin of the net to the destination by routing a starter trace (remove/undo).

3. In Ultiboard, go to the spreadsheet view/ Nets tab and set the 'Topology' of interest to 'Star' for the traces you need matched.

 -> This changes the Max Length and Min Length in the Nets tab from N/A to a number allowing you to set the min/max trace length

4. Set the Min Length of the nets to an appropriate value for your application (it will need to be at least the value of your starter trace in step #2)

  -> Set the Max Length to the minimum + 50 mils or so (Ultiboard will do a relatively good job at attaining the minimum value but give it some room)

5. Go to the Autorouter/place settings and set the Routing mode to: Gridless (this will give the router flexibility to go off grid and match lengths)

6. Highlight the traces of interest and Autoroute these (Autoroute -> Autoroute Selected Nets).

Some Tips:

a. Do this routing first if possible

b. Restrict routing to a single layer if possible (restrict routing layers -> Routing Layers in the Nets tab)

Here is a simple example in Multisim: 

After autorouting in Ultiboard as described:

 

Hope this helps,

Regards,

Patrick Noonan

National Instruments