L-VIS User Manual
294
LOYTEC
Version 6.2
LOYTEC electronics GmbH
15.4 Local Data Point Capacity
BACnet models are currently fixed to a maximum number of 512 local server objects. In
most cases, the L-VIS device operates as a client, retrieving and controlling the value of
server objects on other devices. Therefore, there are usually not many server objects
required on the L-VIS device itself. The number of client connections to other devices is
limited only by available system resources and network bandwidth.
CEA-709 models allow setting the capacity for local network variables (including static and
dynamic NVs, excluding NVs which the firmware creates automatically) in the
Network
Settings
dialog, which is accessible from the
File
menu of the main window. The default
setting, which matches the configuration of an empty L-VIS device, is 512 and must not be
changed if the static interface of the device should stay at default configuration. If the static
interface is allowed to change, the capacity may be increased to support up to 1000 NVs
using the input field
Max. Number of NVs
. Keep in mind, that an increased NV capacity
requires system resources which may otherwise be used for the project, so this setting
should not be set significantly higher than necessary.
See also section 15.10 regarding device resource limits.
15.5 Avoiding Update Loops
Especially when a lot of data point connectors and mathematical objects are used in a
project, the danger of accidentally creating update loops increases and the user needs to be
aware of this problem.
An update loop means that a single update of one data point causes a chain of following
updates which does not end, because one of the following updates again triggers the
original update. For example, register A is used as input for a mathematical object which
writes its result to register B, while at the same time the value of register B is copied into
register A using a data point connector.
The configuration software is able to check for such loops when they are caused entirely by
internal objects. In such a case, the project cannot be downloaded into the device and a
warning message appears, showing the objects which cause the infinite update loop.
However, the configuration software cannot check loops which are closed via the network,
because it does not have enough information to do this. For example, if a data point
connector is used to connect a switch input SI to a switch output SO, this in itself does not
constitute a loop at all. But when the update of SO on the network is sent to a lamp actuator
and the lamp actuators feedback output is connected to the switch input SI, the result may
be an infinite update loop between the L-VIS device and the lamp actuator, depending on
how the actuator behaves. Once the L-VIS sends out an update on SO, it will be received by
the lamp actuator. This may cause the actuator to send out an update on the feedback
output, which will be received by L-VIS on the input SI, which in turn will be copied by the
data point connector to the output SO and so on. The result can have adverse effects on the
network performance and the performance of the devices in the loop, so special care should
be taken to avoid such setups.
15.6 XML Support
Similar to the XML import/export function for individual objects, as explained in section
8.5.4, it is possible to read and write the entire project file in XML format. The easiest way
to do this is to select XML format from the file format dropdown list in the file save dialog,
which opens when the command
Save As…
is selected from the
File
menu of the main
window. Alternatively, use the command
Export XML > Project…
from the
File
menu.
