General »  VNC


How do I open a VNC Session in Single Mouse Mode?

There a command line parameter called RelativePtr which if set to True will launch the viewer in single mouse mode.

<PATH>\vncviewer.exe RelativePtr=True <IPADDRESS>

For example:-
C:\Program Files\RealVNC\VNC Viewer\vncviewer.exe RelativePtr=True

How to connect without typing a Password


The following instructions work with Real VNC VIewers (below version 6).

The VNC viewer allows you to save your current connected session, including the username and password that you used to login.

  • First you need to create the config file.
    • Launch vncviewer.exe
    • Enter the server you want to connect to
    • Enter your Password
    • Right Click Top of VNCViewer Window and select Options
    • Make any changes that you want to be used as the default for the server/host you are connecting to
    • Click the Load / Save tab on the VNC Viewer Options
    • Click the Save As button
    • Save the .vnc file as whatever name you like and put it where ever you want.
    • Click Save
    • A VNC Viewer: Warning window will appear asking if you want to include the VNC Password in the configuration file Click Yes if you want to save it.

  • Create a VNCViewer shortcut on your desktop
  • Right mouse click on the shortcut and select properties
  • Under the Shortcut tab, add the following command line option to the end of the Target file information: -config <VNCFILEPATH>

For example:
“C:\Program Files\VNC\vncviewer.exe" -config "c:\temp\test.vnc"

  • Press OK

How do I improve the latency if my bandwidth is low

To lower the latency, there are a few things that you can do. Lowering the picture quality and colour depth will reduce the amount of network bandwidth required. Changing the remote hosts desktop resolution will help too.


  • Make sure you have set JPEG as the Server Preferred Encoding.
    • Login with a VNC Viewer as Admin
    • Click on the Configure button in the top right corner
    • In the Configuration menu, choose Unit Configuration.
    • Set Server Preferred Encoding to JPEG (Default).
  • Changing the Video Quality and Colour
    • Login with a VNC Viewer as Admin
    • Press F8 to raise a menu
    • From the list, choose Properties
    • In the Properties dialog window, go to the Expert tab.
    • You will be presented with a list of advanced options.
    • Try lowering the Video Quality setting.
      • Auto - Default
      • High
      • Medium
      • Low
    • Try lowering the ColorLevel setting and choose fewer colours.
      • 8-Colours (RGB111)
      • 64-Colours (RGB222}
      • 256-Colours (PAL8} - Default
      • Full Color (Full)

Other VNC Products

For products such as the ALIF2112T, ALIP-GOLD, AL-IPEPS, AL-IPEPS-DA, ALDIPEPS and CATxIP switches.

    • Login with a VNC Viewer as Admin
    • Press F8 to raise a menu
    • From the list, choose Options
    • In the Options dialog window, go to the Colour/Encoding tab.
    • Try changing the Preferred encoding. There are three options, ZRLE, Hextile and Raw. The default is Auto select which is chosen based on network speed.
      • ZRLE - Most effective on slow networks
      • Hextile
      • RAW - Most effective on fast networks.
    • Try lowering the Colour Level and choose fewer colours.
      • Full
      • Medium (256 colours)
      • Low (64 colours)
      • Very low (8 colours)

Further Information

Other factors such as video noise and dithering can cause the bandwidth to be higher than usual, even when the host's video output is inactive. The VNC engine is designed to send over all the changes that are occurring on the screen. Video noise will cause all of the screen to be transmitted rather than only those parts that are changing. If you go to the Video Settings page on the VNC Viewer (Controls -> Video Settings), you can typically see a Display Activity percentage. If the percentage is not 0% (or very close too) with an inactive screen, then you have either video noise which is typically seen on analogue, or the graphics card you are using is employing dithering. Dithering is a technic used by older graphics cards to make it look like they support more colours than they really do, by constantly changing the pixels on the screen to trick the eye. It may be possible to disable dithering on the graphics card, please contact the graphics card vendor for instructions.

As a general rule of thumb, always choose a VNC product that matches the host's video output type and do not use video conversion. For example, if you have a VGA output. then use the AL-IPEPS or AL-IPEPS-DA, however, if you have a DVI or HDMI output then use an ALD-IPEPS or IPEPS-PLUS. Analogue video is a noisy video format, if you try to convert VGA to DVI and then use a digital version like the ALD-IPEPS then this will create lots of unwanted network traffic. The VGA IPEPS products are designed to handle the inherent noisiness of the signal better, whereas the digital versions are not. since this is not expected from a digital signal.

How do I find the Firmware version via VNC?

In order to find the firmware version, please do the following:-

  • Connect to the product using the appropriate VNC Viewer
  • Login in as an admin user
  • On the menu bar at top right-hand corner, press the Configure button.
  • From the Configuration menu, choose Unit Configuration.
  • The firmware version will be displayed at the top of the settings.

    VNC Firmware Version

Can I Copy and Paste between the VNC Viewer and Remote Host?

The Viewer does not support two-way copy and paste. However, it is possible to copy up to 250 ASCII text characters from the host running the VNC Viewer, and then send them to the remote host computer.

  • Open the VNC Viewer and connect to the remote host.
  • Copy up to 250 ASCII text characters into the clipboard of the host running the VNC Viewer.
  • From the VNC Menu, choose Controls and Keyboard Control.
  • In the Keyboard Control dialog window, press Paste Clipboard.
  • This will send the text to the remote computer.

    VNC Pastepng

How can I hide the Menu Bar at the top of the VNC Viewer?

  • Connect to the product using the appropriate VNC Viewer
  • Login in as an admin user
  • On the menu bar at top right-hand corner, press the Configure button.
  • From the Configuration menu, choose Unit Configuration.
  • By default, the Menu Bar Toggle Hot Key option is set to None.
  • You can assign a Function Key (F5-F12) to Hide and Show the Menu bar.
  • Once assigned the Display Menu Bar for New Connections check box will be available to decide if the menu bar is shown when you connect.
  • Press Save to commit the change.

    VNC Hide Menu Bar

Page last modified on Thursday June 10, 2021 13:37:51 GMT-0000