Brand:

• AMX

Models:

• DGX 100 series

Question:  

How do I Disable PreQual (to Restore AIE Extraction on DXLink outputs)?

Answer:

Background:

In the latest DGX releases (Public Release 3.6.22 and Hotfix 3.4.6-2) a new feature (“PreQual”) was introduced to help manage routes to prevent video from being passed to outputs that can’t support the incoming video (i.e.  trying to send 4K video to a 2K output).  Similarly it blocks routes with INVALID video (aka.  garbage video, unsupported, etc.) from cascading downstream and causing output card failures.  Basically the feature pre-qualifies all incoming video AND checks the planned routes to insure (a) the video is valid and stable and (b) the output cards/channels/sinks are capable of handling the routed signal.
An unavoidable side effect of this is that the CPU must block routes to DXLINK outputs (2K or 4K) that do NOT have an endpoint attached since it cannot get status back from the empty connector.  This means that AIE extraction on an empty DXLink output is not possible as long as PreQual is enabled.  This doesn’t affect the 2K HDMI outputs since they can respond with their status even without a sink attached.

Workarounds:

Option 1:

It is best to use an empty 2k HDMI output instead for any AIE extraction on the output side.  Until recently (2017) the empty HDMI output port was not a stable extraction point for audio.  However, that issue was resolved in output image 1.4.3.3 and has been working great ever since.  It is not affected by this PreQual issue.

Option 2:

It is possible to disable PreQual which is described below but keep in mind this is only recommended as a last resort since the PreQual feature has a lot more benefits to blocking garbage video, etc.  So ideally it should be left enabled.  However in the case where option 1 workaround is not possible, here are the steps needed:

PreQual Disable Steps:

1. Connect to the DGX Shell
   1. Option 1.  Serial port @ 115200 baud
   2. Option 2.  ICSLAN port & telnet to 198.18.128.1
2. This will put you into the DGX_SHELL debug console
   1. Press Ctrl+C to get the prompt back
3. Then copy and paste the following command exactly as is after the DGX_SHELL> prompt: set shell_start_cmdstr_COM1="set mcpu_prequal_enabled=OFF"
4. This disables PreQual and makes it default to disabled any time the system is rebooted.  Otherwise it will revert to enabled on power cycle.

Additional Information:

The 4K60 I/O boards will ONLY work with AIE cards in these two scenarios below:

• Extraction FROM the 4K60 INPUT card
• Insertion TO the 4K60 OUTPUT card
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