In the process of developing a PCB design, a multitude of experts are involved in the verification of the design. These experts and various other stakeholders can be from your own company or from your manufacturer and they will be interested in particular aspects of the PCB design process. Sharing relevant data with respective stakeholders and experts from various domains is important to receive appropriate feedback and this largely depends on the data extraction capability of the PCB design software. Cadence Allegro® Layout Editors make data extraction and sharing easy by providing an in-built mechanism that converts binary design data into a readable text file format.

What is Extracta?

Extracta is a utility that reads a binary representation of layout files and translates the data into an ASCII file format. This utility is available both on Windows and Linux platforms. By using the automated data retrieval capability of extracta, you can extract specific data from Allegro design databases. The file generated by extracta is in ASCII text format and contains required database information that can be formatted and sorted before you send it out for analysis.

Running Extracta

Usually, you run extracta when the design is completed, but you can run the command at any time of the design process in two convenient ways: 

• Entering the following command syntax from the command line:

extracta <layout_file_name> <command_file_name> <output_file_name>

• Launching Extract UI from either menu Tools – Reports – New/Edit  or by typing the extract_ui command in the layout editor command window:

But before running extracta you need to specify the data that you want to extract in a format that can be interpreted by the tool. Here is the flow of files for data extraction tasks:

• Command File: Input file, which contains data fields and selection criteria for data values you want to extract from the layout design database. This file is called a view.
• Design Database: Layout file (*.brd, *.mcm, and *.sip)
• ASCII File: Output file (*.txt, *.rpt, or *.htm file), which contains the extracted information from the design specified in the command file. The output file is composed of many text record representations of the database.
• Log File: Output file, which contains all the errors and warning messages to command if the extraction process fails 

The command file is a text file (.txt) that can be written manually in any text editor or generated through extract UI. Each line of this text file is called a record and can be of the following types:

To extract multiple views, use multiple END records in a single command file. The END record delimits multiple extracts in a single command file. When extracting multiple views, you must specify multiple output file names. You can also add property names as data field records in the command file. It is possible to extract a property from any element that might have that property, or from a specific element type in the design through the extracta program.

Sample Command File

Here is a sample extract command file with multiple views:

Creating Command File Using Predefined Views

Layout editors provide a set of predefined values that contain chosen data fields, called baseview files (_bv). These files are located at \share\pcb\text\views in the install directory of the software. You can customize these preexisting baseview files per your requirement and extract multiple views in one go. The baseview files consist of all the data fields associated with a particular view. To create your command file, simply copy a partial or complete baseview file of the relevant data field. You can further specify specific values to the data fields and combine selection records.

The following image describes predefined database views and descriptions. 

Again, it is up to you whether you want to use a text editor or Extract UI to modify baseview files.

Analyzing Extracta Output

The extracta command outputs a text file when run from the command line. The text file contains two header records followed by one data record per extracted element. Each record in the output file starts with a record-type character. The command supports three record-type characters:

• A Record: Specifies labels for each data field. These labels are the same as the data field names in the command file.
• J Record: Specifies global data about the layout design. For example, name, date of execution, design extents, design units, DRC status, and so on.
• S Record: Specifies data values for the fields named in the A-record, in the same order as it gives the names.

The standard separator character between every field in all records is the exclamation sign (!).

Sample Extracta Output File

When executing the same command file by loading it in the Reports UI, the output is generated in the .rpt or .HTML format. 

Wrapping Up

In this post, I briefly introduced you to Extracta. To new users, I will suggest the existing documentation and the article Using Extracta in Allegro PCB Editor at the Cadence Online Support site. You will get more insight as you start using extracta, and will become proficient in no time!