L-VIS User Manual
258
LOYTEC
Version 6.2
LOYTEC electronics GmbH
be used to simplify device installation. If a fresh project is started, the VNC option is turned
off by default.
To connect to the VNC server, install one of the available VNC clients on your PC or other
device (VNC clients are available for PDA and even some cell phones) and connect to the
device. You can then remotely access the LCD display of your device and use the mouse to
operate the touch screen.
If the connection fails, the most common reasons are:
The maximum number of connections is reached.
There are other clients connected and the new connection requests exclusive
access. Check the settings of your client and disable exclusive access in this case.
There is one other client already connected and holds an exclusive connection.
If more than one user is connected to the same device, everyone will see the same display,
just like VNC used on a PC.
NOTE:
LVIS-3E100 and LVIS-ME200 devices use a VGA color map (256 colors). For these
devices, it is therefore most efficient to transfer the color map to the client and then only
transmit the color index for each pixel (one byte per pixel). If the VNC client supports this
mode (color map mode), the VNC server on the L-VIS device will tell the client that this is
the preferred display mode to optimize speed and bandwidth usage while keeping a fully
accurate rendering of the project colors. However, many clients only support true color
modes, where either two or more bytes per pixel need to be transferred or the color
resolution will be dramatically reduced. A client which supports color maps is RealVNC.
11.5.2 Remote Data Access (FTP)
To access trend and event logs created by the respective controls, a dedicated FTP access is
available. For firmware versions 4.0 and older, the user name and password specified here
can be used to log in using an FTP client and download the required data files. Starting with
firmware version 4.0, the operator account is used for this purpose. The operator password
can be set on the Web-UI of the device.
11.5.3 Data Point Update
This area defines how network input data points are updated with new values. There are
two basic modes available, which are controlled by the option
Use dynamic polling:
Enabled:
The device will distinguish between active and inactive data points. An
active data point is one which is either currently displayed by a control on the
LCD screen, displayed on the web interface, or a data point which is connected to
a trigger, action, trend, or formula and thus must be monitored all the time.
Disabled:
All data points are treated the same, no matter if and where their values
are currently used. Active polling continues for all data points as specified in the
properties of each point.
With dynamic polling enabled, the device will only fetch values for currently active data
points. Monitoring will still be done at the rate specified for each individual data point, but
all inactive data points will stop any polling or subscription activity in order to reduce the
network load as much as possible.
To avoid stale data in data points which are not subscribed for extended periods of time, the
option
Enable background polling
can be used. The device will go through all otherwise
inactive data points and poll the current value at the specified poll rate. This ensures that in
cases where a data point becomes active after a long period of inactivity, it already has a
