The Pro-C controller is supplied with a factory-installed base module for up to 4 stations on the PC-400 and up to 3 stations on the older PC-300. Additional modules may be added in increments of 3 stations (PCM-300) or a single 9-station (PCM-900) to expand the controller’s station capability to 15-16 stations. Additional modules are sold separately. After inserting station modules, pressing the reset button should be done to allow full recognition. Below you will find information on the compatibility of different modules for both the PC-300 and PC-400 controllers.