Why to use Allegro System Capture – Reference Designator Pattern

Reference Designator (RefDes) is a unique identifier that indicates parts in a design.

It is often required by designers to have a customized pattern of reference designators for easy identification of the circuitry. For example, you may want to have reference designators, which include page numbers, block details, and so on.

System Capture gives you an option to configure the RefDes numbering by defining a pattern.

You can define the RefDes pattern in Edit > Preferences > ECO/Packager. The pattern defined using the GUI option is applicable to project level.

Apart from the GUI option, you can create your desired RefDes pattern by using the REF_DES_PATTERN cpm directive. This cpm directive is used to control the RefDes numbering at site level as well as project level.

The REF_DES_PATTERN directive is defined in the CANVAS section of the cpm file.

$PHYS_DES_PREFIX utilizes the PHYS_DES_PREFIX property specified for the part (that can be U, R, C, and so on), and then attaches the following information to it.

$PAGE: Page number where component is placed

[0-9]: Number range used for numbering RefDes

(00): The number from which numbering needs to start

For resistors placed on page 1 of the design, the RefDes assigned as per the above pattern is as follows:

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