Some machine builders may also integrate their custom control systems into the overall plant control system. Many system integrators, machine builders, and OEMs maintain their own in-house panel shops. They may use their own software products or specialize in configuring commercial software packages. Many software houses are also value-added resellers. The value they add may be other compatible products or services such as software configuration, troubleshooting, or complete system integration.
VARs generally focus on a particular vendor's products or a particular industry's applications.
VADs also maintain product inventories and provide technical advice. Other vendors have gotten into the system integration business as a matter of necessity. The advent of digital drives has enabled a host of advanced motion control functions. There are also several vendors that offer their engineering services along with the services of third-party system integrators. Starting from scratch Conversely, a few system integrators that started out selling just their engineering services have introduced better products, often the software tools they originally developed for their own use.