The Agilent E6232A / E6233A / E6234A / E6235A are a C-size, 2-slot, message-based, PC controllers and can be used in either the E84XX series, the E1401B, or the E1421B Mainframe. Embedding the controllers in the VXI chassis allows direct computer access of other VXI devices, system memory, and triggers as though they were part of the controller hardware. Therefore, you don't need a separate command module.