Reference Designators

Objective: To illustrate how reference designators are managed by Duro and should be leveraged to map out your needs.

Difficulty: Easy 

In this article:

1. Overview
2. PCBA structure
3. Importing reference designators into assemblies
4. Editing assemblies directly with reference designators
5. Importing reference designators via Altium

Reference Designators (Ref Des) are the building blocks of electrical assemblies, functioning as shorthand component titles. They provide designers with technical language to identify components on a Printed Circuit Board (PCB), enabling the creation, design, and production of the assembly. Read on to learn the different ways to update your assemblies in Duro with reference designators: adding from your library, adding from a file, creating components manually, editing the REF DES column of an assembly, or importing through the vendor.

Overview

Reference designators provide information about where components in electrical assemblies are located on a Printed Circuit Board (PCB). Reference designators (also referred to as "Ref Des") follow a pattern that enables designers to reference individual components in PCBAs, design and layout documents, schematics, and assembly data. Think of Ref Des values as geo-tags for all the parts affixed to the PCB. Every reference designator is unique and never repeated, enabling users to pinpoint the precise location of a component being referenced. This helps avoid confusion, saves time, and ultimately makes the building process possible.

When a designer uses a reference designator, other members of the design team will know exactly what component they’re referring to, thus providing language to talk about a series of otherwise identical components and simplifying communication channels. Without reference designators, assembling and debugging an electrical assembly would be impossible. This is why it is critical to include Ref Des values when importing your Bill of Material (BOM) for an electrical assembly into Duro.*

Note: A flattened BOM will not show REF DES or notes since these fields are in the context of the assembly, not a specific component. 

Reference designators are shown in wiring diagrams and schematics, which create a map of how all components within an electrical assembly fit together.

Example of a schematic

Prefix key

Reference designators usually consist of a one or two-letter prefix followed by a number (e.g., BT50, C29, F5, LS800). This alphanumeric combination can communicate schematic location and specify the component type the reference designator represents. Although the prefix doesn't necessarily have to specify the PCB element the reference designator connects to, it can be used to do so if needed. For instance, "C5" refers to a capacitor, and "R30" refers to a resistor.

PCBA structure

In order to understand how Duro manages your reference designators, it's important to understand the structure of the PCBA and the significance of the Electrical Bill of Materials (EBOM). A PCBA is made up of two things: the PCB and an EBOM. The PCB is the physical board used in the assembly, and the EBOM lists all child electrical components used within the assembly. Although Duro places no restrictions on listing components directly within a PCBA or on the type of assembly used for child components, we recommend using an EBOM for a variety of reasons: it upholds the assembly structure, keeps your data organized, and allows for the EBOM and PCB updates to be revisioned independently if needed down the road. 

Duro displays reference designators for the following component assembly categories:

1. EBOM 
2. Printed Circuit Board Assembly (PCBA)
3. Sub-Assembly
4. Top Level Assembly
5. Cable Assembly 

For more information on how to create a PCBA, please refer to our article on Creating PCBAs.

Importing reference designators into assemblies

Duro users can upload Ref Des values directly into their Duro assemblies. There are four ways to do this: adding from your library, adding from a file, adding from a vendor (Altium), or creating manually.  Please note that Ref Des values are specific to each Assembly, so this field will only be accessible when importing spreadsheets directly into a component assembly. 

Once your EBOM is created in Duro, head to the Assembly tab. Then, once in edit mode, choose your preferred method of adding components and remember to save your changes once concluded. To learn more about how to add components to an assembly, please visit Adding Components to an Assembly. 

Editing assemblies directly with reference designators

If you need to quickly insert or edit reference designators, you can edit an assembly by manually typing into the REF DES column cells of the assembly table. Once in edit mode, simply click into a cell under the REF DES column. Enter your reference designators for the child components of the PCBA, then save your changes.

Importing reference designators via Altium

It is also possible to import reference designator information to Duro through Altium. As an Electrical Computer Aided Design (ECAD) tool, Altium has the capability to map out reference designators to Duro. Once you release your PCBA, PCB, and/or EBOM from Altium to Duro, reference designators can be viewed in the corresponding Duro component assembly table.

To learn more about how to release a project from Altium to Duro, please visit our article on Altium.