FAQ: PoE Module Requirements

FAQ: Is a battery required for PoE Module Installations?

A working battery backup is recommended for all PDK PoE Installations. 

Without a battery, a power-related compatibility issue can occur when a PDK PoE Module (RMPOE) is connected to certain network switches that use the PoE+ (802.3at) or PoE++ (802.3bt) standard. In these specific configurations, the controller may fail to power on or may experience intermittent power cycles.

This behavior happens because PDK PoE Modules are designed to be highly energy-efficient, drawing only the minimal current required to power the controller. However, modern PoE+ and PoE++ switches deliver significantly higher power budgets and expect a larger, faster current draw during their negotiation process. If the controller’s initial request is too low or not detected in time, the switch may incorrectly assume no device is connected and shut down the port, which can lead to a reboot cycle. 

To ensure reliable operation, a working battery backup is recommended for all installations using a PoE Module, regardless of whether the network switch itself is connected to a UPS. The battery serves as the primary power source during the controller’s startup sequence, allowing it to bypass any delays or interruptions caused by PoE negotiation with the switch. By the time the switch port becomes active, the controller is already fully powered and stable. The battery backup will also ensure that the controller remains operational if the UPS becomes depleted or if the connection to the PoE switch is unavailable.

Approved Configuration (Recommended):

Network Switch (PoE+/PoE++) → PoE Module → Controller → Battery → Readers

Please ensure that this technical requirement is followed for all new and existing installations that utilize a PDK PoE module. This practice will prevent power-related service calls and provide the highest level of system reliability.