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Video: Why is my AP8XXX Rack PDU reporting communications lost with Phase Meter?

Article available in these languages: Spanish


My AP8XXX Rack PDU is periodically or constantly reporting messages similar to below in its event log:
Rack PDU: Communications established.
Rack PDU: Component communications established with Phase Meter.
Rack PDU: Communications lost.
Rack PDU: Component communications lost with Phase Meter.

Depending on the model of Rack PDU, you might also see multiple events for communication established/lost for Phase Meter 1, Phase Meter 2, and Phase Meter 3.

Furthermore, your PDU may not provide current readings and 0V for incoming voltage while reporting these messages.

Product Line
  • AP8XXX Rack Power Distribution ​​
    • AP88XX Metered Rack PDU
    • AP84XX Metered By Outlet Rack PDU
    • AP89XX Switched Rack PDU
    • AP86XX Switched with Metering By Outlet Rack PDU
  • All serial numbers
  • All firmware versions
  • New or existing installations


These messages are most commonly caused by a a loose wire. They indicate that the on-board Network Management Card has lost communication with the Rack PDU monitoring hardware. Less commonly, this could be due to a timeout within the Rack PDU's internal communications.


The following steps should be taken in troubleshooting this issue.
  1. Verify the Rack PDU firmware is up to date by visiting https://www.apc.com/tools/download/index.cfm and looking for the latest SFRPDU2G firmware version. You can do this by selecting the drop down menu under Filter by Software/Firmware and select Firmware Upgrades - Rack Power Distribution to filter the results.
  1. Reseat the Rack PDU display connector. In order to also properly power cycle the display, remove the connector for at least five sections. Instructions are attached to this knowledge base article below entitled AP8XXX_Rack_PDU_Display_Replacement.pdf. Verify any visible wire connections on the display module are secure at this time.
As noted in the instructions, the Rack PDU must be completely powered down to safely perform this step.
  1. If any spare PDU display modules are available from the same model of Rack PDU are available, consider trying this spare display (by using the Rack PDU Display Replacement Instructions mentioned above) to see if the problem follows the display module or the Rack PDU chassis.

If the steps above do not remedy the issue, the Rack PDU display module or Rack PDU may need to be replaced. Contact APC Support for replacement options or if you have any additional questions. Please be prepared to provide the event.txt, data.txt, and config.ini files from the Rack PDU(s) displaying the issue. Instructions on how to do that are outlined here.

The following video offers a tutorial for replacing the Display Module (0J-0G-9473, 0J-0G-9470, 0J-0M-81332) within APC Second Generation (Gen 2) Rack Power Distribution Units (PDU) AP8XXX:

APC Nigeria


AP8XXX_PDU_Display_Replacement_JSAI-89CSLV_R1_EN.pdfAP8XXX_PDU_Display_Replacement_JSAI-89CSLV_R1_EN.pdf [115.86 KB]
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