Configuration Steps : Cisco Managed Switches with DataCharger & VidaCharger PoE Adapters

Sep 21, 2024 - by Steven Cheung

Cisco managed switches are a very popular networking option. By default, most switches are configured "out of the box" for energy efficiency to lower total cost of ownership. While this is ideal in most scenarios, this default configuration can cause problems when the switch is used as a high wattage (25-50+ Watts) PoE-based power source, such as when used with our DataCharger, VidaCharger Ultra, or other PoE adapters.

---

Problem / Issue / Symptom:

When connected to a Cisco managed switch, a VidaCharger, DataCharger, or other PoE+/PoE++ adapter doesn't appear to draw power. The same adapter, when connected with an unmanaged switch or injector of sufficient wattage, has no issues.

When improperly configured, various symptoms will present as:
- Tablet receiving charging power -> pause with no power -> charging power returns & the cycle repeats
- Tablet receives charging power, but does not connect via Ethernet for a wired data connection

Follow the steps below to increase power output from our Cisco switch and easily resolve these issues.

Reason:

Cisco switches are generally pre-configured to auto-negotiate all power requests and limit output to 15.4W (as per 802.3af specs) to conserve power. Configure your switch to skip detection, and send 30W by default.

Solution:

Follow the steps on this Cisco document (linked below) to enable 2 Event Classification, which enables higher power output:

• Configuring 2 Event Classification
  https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960cx_3650cx/software/release/15-2_7_e/configuration_guide/b_1527e_consolidated_3560cx_2960cx_cg/configuring_2_event_classification.pdf


• Double check and ensure your PoE Port can output PoE+ [30W], PoE++ [60W] (For iPads & Galaxy Tabs), or up to 90W of power (For Microsoft Surface Pro tablets). Many PoE ports are limited to only outputting PoE regular (15W) and would not be sufficient to power newer, USB-C based tablets.

Assuming there are no other issues / causes (such as patch panels or other interconnects), this should resolve most power output issues on Cisco switches. If the symptoms persist:

• [1] Follow and check steps B (Check / replace USB cable) and C (Swap / test CAT5 cable) on this guide:
  [Troubleshooting Guide] 48VDC USB-C DataCharger / VidaCharger Ultra [to] 3rd party PoE Switch / Injector


• [2] If using a Microsoft Surface tablet, try:
    · A. Rebooting the device, to reinitialize its USB Power Delivery Drivers
    · B. Check for Windows updates for the Surface tablet, especially for optional Chipset and USB device drivers
    · C. Configure the device so that its display is always on + set it to NEVER Sleep nor Hibernate - which can interfere with its USB Power Delivery Drivers


• [3] Contact us directly for further assistance if all of the above steps have been tried, but symptoms still persist