Issue link: https://resources.pcb.cadence.com/i/1526746
Understanding How the Constraint Manager Works The Constraint Manager can be confusing at first glance. How do you know which constraints to set up? The Constraint Manager uses the following method to apply constraints: First, you set up rules (we'll use 'rules' and 'constraints' interchangeably throughout this guide) in one part of the tool, then you apply those rules selectively to different nets, groups, and classes of nets. For example, let's say we want to create Electrical rules that can be applied to any net, group of nets, or net class. In the CM, you would first set your rules in the Electrical Constraint Set (ECS) section of the tool (see below). At first glance, this method may seem redundant or unnecessary. Why not simply identify the objects you want to apply rules to first, then define your rules for those objects? The issue with that approach is that you'd need to manually track all your rules for every object in a list and worry about prior- itizing them correctly. Moreover, if you overlook an object or relationship, you could face significant problems later. By using this modular and categorical approach to constraint management—keeping rules separate from what they're applied to—, you gain flexibility, reduce the mental burden of tracking specific rules for specific objects, and can create blanket rule sets and categories. As you'll see later, you can still apply specific rules when necessary. This approach to constraint management is incredibly robust, efficient, and flexible. If you need to change a rule for entire groups of nets, you can do so simply by modifying the rule itself or swapping out a rule created in the Constraint Set section. Even if nets change through PCB and design updates, you can maintain the same rules and apply them to the new nets, or incorporate the new nets (along with their changes) into existing rules. The flexibility and power of this approach make it the current gold standard for rules and constraints management. Another powerful feature of the CM is the ability to locate your nets on your schematic or PCB directly from the constraint manager. 5 www.cadence.com Part 1 of 5