The FiberPlex PSM-2010 and PSM-3010 are power supply modules designed to be inserted into the RMC-2xxx and RMC-3xxx rack mount chassis, respectively. The modules provide an operating voltage through the chassis backplane to power up to nine fiber optic isolator units. Each rack mount chassis is shipped with one power supply module. For additional reliability and security, a second Power Supply Module (PSM) may also be added for power redundancy. If the first PSM fails, the second PSM will take over the entire load and carry on normally. Additionally, if one PSM fails, an onboard alarm will sound. An LED indicates that the +9VDC output voltage is present, and that the module is operating properly.