Technical Service Bulletin: PoE Module Compatibility and Required Use of Battery Backup

TSB No: PDK-TSB-2025-046

Date: 08/27/2025

Subject: PoE Module Compatibility and Required Use of Battery Backup

Product(s) Affected:

• All PDK Controllers with a PoE++ Module (RMPOE) installed

1. ISSUE

PDK has identified a power-related compatibility issue that can occur when a PDK PoE module is connected to certain network switches that utilize 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.

2. CAUSE

PDK's PoE modules are designed to be highly energy-efficient, drawing only the minimal current required to power the controller. Modern PoE+ and PoE++ switches are designed to deliver a significantly higher power budget and, as part of their power negotiation protocol, may expect a much larger and faster current draw from the connected device.

If the controller's initial power request is too low or not detected in time by the high-power switch, the switch port may incorrectly assume that no device is connected and shut down power. This is a characteristic of some high-power switch chipsets and not a fault with the PDK module.

3. REQUIRED REMEDY

To ensure reliable operation of any PDK controller powered by a PoE module, the controller must be connected to a functioning battery backup. This is a mandatory step for all installations using a PoE module, regardless of whether the network switch is on a separate UPS.

The battery serves as the primary power source for the controller during the critical power-on sequence. This bypasses the potentially problematic PoE negotiation with the switch and ensures the controller is already fully powered and operational by the time the switch port becomes active.

The following is the only approved configuration for a PoE-powered PDK controller:

Network Switch (PoE+) --> PoE Module --> Controller -- Battery -- Readers

4. RECOMMENDATION

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 ensure the highest level of system reliability for your customers.

5. SUPPORT

For any questions regarding this technical bulletin or for assistance with an installation, please contact PDK Technical Support at (801) 317-8802 or support@prodatakey.com.