How Values are Assigned to Parts

This task shows you how values are assigned to parts that you have placed.

Placed parts get their values from various sources, a list of which is provided below. This task explains the rules that govern how these values are assigned to parts. Users may need to know this information so that they can assign attributes in such a way that the parts they place obtain the correct values. In most cases this follows a standard pattern, but some users may need to change the way in which values are assigned in order to meet special needs. Only values are derived, not the attributes. An attribute must be defined on both the part and the 'parent' object or a value cannot be assigned.

Values can be assigned to a placed part from the following seven sources:

  • From the part itself.
  • A run.
  • A connector.
  • Based on a specifications catalog.
  • A line.
  • From a 2-D function (in the case of schematic driven design only).
  • Defined by the user.

If you place a part in space then the part will inherit data from the Line ID menubar. See Using the Line ID Menubar. If the part placement is done schematic driven, then the part will inherit data from the schematic. If a property has not been given a value in the schematic, then it will obtain data from the Line ID menubar.


If a value has been assigned to an attribute during part build time, then that value will be used when the part is placed. Examples of attributes whose values are defined in the part are: material category, material code, part numbers. 
2. If a part is placed on a run:

A bendable part will pick up the bend radius and the nominal size values from the run. Other parts will pick up the nominal size value only.

3. If you select a connector before placing a part then the values will be derived from the connector. The image below shows a connector with attributes and values displayed.

If the valve shown above had already been placed on a run, and you selected the run before placing a new part, then that new part would have derived values from the run.

In the HVAC Design application, if you select a connector to place a new part, then the values will actually be assigned to the new part. In other applications you will be provided with a part that matches the nominal size and other attribute values.

Some of the attributes typically defined on a connector are those displayed above: wall thickness, rating, end style and nominal size.

  4. If you are selecting parts from a specifications catalog:

If the part being placed does not have an attribute value defined, then the value will be obtained from the specification.

If the value is defined in both the specification and on the part then the value on the part will remain unchanged.

  5. When you are placing a part as part of a line:

If the part does not have an attribute value defined, then the value will be obtained from the line.

If the value is defined on both the line and the part then the value on the part will remain unchanged.

Attributes that are typically defined on the line are: insulation specification, insulation thickness, temperature and pressure.

  6. In schematic driven design:

If the value is not defined on the physical part then it will be obtained from the function.

If the value is defined on the the function and the physical part then the value on the physical part will remain unchanged.

  7. User defined:

During part build time some attributes can be defined as override parameters, which means the user defines the value. For such attributes, users will be prompted to define values at parts placement time.

  8. The application attempts to determine values in the order given above - if the part itself does not have a value it will examine the line, then the run and so on.