Diagnostics: Loss of Sync ProLink5, Port A or B

Potential Symptoms

  • Potential poor image quality. A single loss of sync it not likely to cause visual problems for a display, but if multiple losses of sync occur in a ProLink5 circuit, particularly a system that lacks redundant PLRs, all modules between the points of failure may go blank.

IDM / System Health Event(s)

  • Loss of Sync (ProLink5, Port A or Port B)


  • Product Family: 
  • Product: System Health, IDM
  • Component: PLR
  • Control System: Venus Control Suite


  • The PLR receives ProLink5 data on two ports - A and B. A loss of sync on one port will cause the PLR to switch to the other port. While a loss of sync itself is a non-visual event, it may be caused by the reset or failure of a module directly connected to the PLR, and therefore may be an indirect indicator of a visual outage.
  • If redundant PLRs are not configured, a persistent loss of sync on a ProLink5 circuit indicates that module data redundancy has been lost. Another loss of sync on the same circuit will result in a visual outage affecting all modules between the two points of failure.
  • If redundant PLRs are configured, you may experience a loss of sync on a PLR ProLink5 without a loss of module redundancy, provided that all modules are in sync on both ports.


  • If redundant PLRs are not configured, look for events indicating that the module connected to Port A or B (depending on the alert) of the PLR experienced a reset or diagnostic failure, and use the display's webcam to determine if there are any visual issues occurring on the display. 

  • If no such events exist, inspect the Serial ATA cable connection between the PLR and the module connected to  Port A or B (depending on the alert) of the PLR.

  • If redundant PLRs are not configured, determine whether a loss of sync on Port A or B (depending on the alert) of the PLR is expected.

KB ID: DD4303395

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