  The Advanced Photon Source (APS) primary and backup injectors consist of two
thermionic-cathode rf guns. These guns are being upgraded to provide improved
performance, to improve ease of maintenance, and to reduce downtime required
for repair or replacement of a failed injector. As part of the process, an
injector test stand is being prepared. This stand is effectively independent of
the APS linac and will allow for complete characterization and validation of an
injector prior to its installation into the APS linac.
  A modular control system for the test stand has been developed using standard
APS control solutions with EPICS to deliver a flexible and comprehensive
control system. The modularity of the system will allow both future expansion
of test stand functionality and evaluation of new control techniques and
solutions.
