Typically, hardware products are most closely related to the physical plant part of the PERA Architectural Model, while software products are more closely related to the Human and Organizational part. However, even the distinction between hardware and software is not absolute, since most hardware has associated firmware, and often software requires a specific hardware environment. There are also products such as Distributed Control Systems or Programmable Logic Controllers which encompass both hardware and software inextricably bound into a single product.
Organization of software products by user group, and hardware products according to the physical architecture results from the PERA Model Structure. Although shown for simplicity as 3 parallel columns, PERA defines interfaces between Control and Information Systems, the Human and Organizational, and Physical Plant column as follows.
It can be argued that it would be better to relate software products to Work Process or Value Chain Diagrams rather than the Organization Chart, however this is not how products are in reality procured and supported. Financial and Human Resources are provided through the Organization Chart not through Work Processes or Value Chains which span multiple organizational groups (if the work process or value chain does not span multiple organizational groups, there is no difference). Therefore, applying the second rule of project management (Don't cut it where it is thickest), the correct place to establish software interfaces is with Organizational Chart entities.