The CDU is not updating its display
There are 5 potential causes.
1) You are not running the latest version of the NGX, 777 or 747 QOSII.
2) The PMDG SDK will stop sending messages and thus into the Interface software if
- the aircraft is flown and then you return to the flight simulator main menu and re-fly it again;
- switch between different models;
- your default flight is set to use the NGX, 777 or 747 QOS II and then you change to another PMDG aircraft or model;
It will manifest itself as the display on the CDU not updating, although you can use the buttons on the CDU and the aircraft will respond. The Status tab will also show a "NO INCOMING DATA!" message above the Aircraft LED.
PMDG have acknowledged this as an issue with FSX/Simconnect and is why they always recommend to restart FSX after each flight with the NGX, 777, 747 QOS II.
3) It may also be due to the PMDG SDK not being enabled. The enabling of the SDK is automatic. You can check or set the options manually by using notepad to open the following file:
<your flight sim directory>\PMDG\PMDG 737 NGX\737NGX_Options.ini or <your flight sim directory>\PMDG\PMDG 777X\777X_Options.ini or <your flight sim directory>\PMDG\PMDG 747 QOTS II\747QOTSII_Options.ini
and ensure the following exists:
EnableDataBroadcast=1 (if this is set to 0 change it to 1)
EnableCDUBroadcast.0=1 (For the Left position CDU. if this is set to 0 change it to 1)
EnableCDUBroadcast.1=1 (For the Right position CDU. if this is set to 0 change it to 1 if needed)
EnableCDUBroadcast.2=1 (For the Centre position CDU. if this is set to 0 change it to 1 if needed)
4) If pressing EXEC + S on the CDU does not display the setup screen then the CDU has not initialised correctly. The CDU needs to be disconnected (both the power lead and the USB cable) and then the USB cable connected followed by the power cable (the order is important!).
5) You are not running the latest version of the .NET Framework.
The CDU Keeps Powering Off and On
On some systems the Disconnect Timeout and/or the Timeout Threshold defaults to a setting that is too low. Increase one or both of these options in the Settings tab until the problem stops. Alternatively, just tick "Never Disconnect CDU(s)".
The CDU Slows Down or Behaves Erratically
The baud rate setting in the CDU, the CDU windows driver and the Engravity CDU PMDG Interface all must match.
The CDU baud rate can be set by pressing EXEC + S on the CDU. The CDU windows driver is called the Silicon Labs CP210x USB to UART Bridge and can be found in Window Control Panel - Device Manager. By double clicking on the device in Device Manager you will get a config screen to set the baud rate. The Engravity CDU PMDG Interface baud rate can be set on the Settings tab.