# How to develop the " setRC.tcl "  file from a captable for a foreign PDK ?

Tool: Parasitics Extraction

Subcategory: Setting up foreign PDK

## Conversation

### faisaladilquadery
I have a foreign PDK which I want to invoke in openroad. But for that I need to develop the setRC.tcl file. How do I accurately input the resistance and capacitance for the setRC.tcl file . 

N.B : I have a captable for the pdk
I can also generate a spef file from Innovus for the PDK

### maliberty
@vvbandeira @luarss do we have any documentation for correlateRC ?

Note that if you LEF res & cap has values you can use those without a setRC to get started.

### vvbandeira
@faisaladilquadery 
We have a section on the `setRC.tcl` file configuration in our platform bring-up documentation.
https://openroad-flow-scripts.readthedocs.io/en/latest/contrib/PlatformBringUp.html#setrc-configuration

### faisaladilquadery
Thankyou! @maliberty @vvbandeira . I have used the lef file in replacement of the setRC.tcl file . But I am getting **net delay** mismatch between the same path with the same cells for Innovus and OpenRoad. Any Idea why ?

### faisaladilquadery
Thankyou @maliberty I have used the the RCX flow you  mentioned to generate a rc tech file for my pdk and used the tech file to generate a spef in ORFS to obtain a more accurate RC.

### b224hisl
> set_wire_rc is used to set a default layer to use when doing placement based parasitic estimation. There is no meaning to multiple layers here as there would be no way to divide up the estimate meaningfully.

So I'm confused why it needs to set jsut one layer, do you mean only placement based parasitic estimation is related to `set_wire_rc` ? If there' s no way to divide up the estimate meaningfully, the layer can be set randomly?