1. A system for generating a custom device description file, the system comprising: a processor, the processor including a memory medium, the memory medium including a device description file generator, the processor operable to execute the device description file generator; the device description file generator operable to receive a description of a data item for a machine vision system, the data item being included in a network item from a first device configured as a part of the machine vision system, the data item including one or more data-item process variables; the device description file generator operable to map the data item from the first device into the network item, the network item residing in the first device; and the device description file generator operable to generate a custom device description file for the machine vision system, the custom device description file describing the data item included in the network item and including a custom process variable that is not included in the data item and that does not correspond to any of the one or more data-item process variables, wherein the first device further includes a configuration tool, the configuration tool operable to provide the description of the data item to the device description file generator.