L-VIS User Manual
179
LOYTEC
Version 6.2
LOYTEC electronics GmbH
NOTE:
A notification received by the L-Vis application from a data point may trigger execution of
actions or commands like visibility or color changes, or it may result in a recalculation of a
formula and cause a new notification about the changed result to be sent.
When the value of an output data point is updated, an update is usually sent out onto the
network. The property
Send-On-Delta
decides how the update is reflected on the network.
If send-on-delta is inactive, each update of the value is sent, even if the value does not
change. If send-on-delta is active, only value changes are sent. The send-on-delta property
is only valid for output data points.
For analog data points, the COV or send-on-delta takes an extra argument, which specifies
by what amount the value must change to regard it as a change for action. Both, COV and
send-on-delta for analog data points check the
Analog Point COV Increment
property. A
change is detected, if the value increment is bigger or equal to the specified increment. If
the property is zero, all updates are considered.
10.1.7 Custom Scaling
Custom scaling is applied to all analog data points when they communicate values to or
from the network. This feature can be used, if a network data point has engineering units
not suitable for the application (e.g., grams instead of kilograms). The scaling is linear and
applied in the direction from the network to the application as:
A =
k
N +
d
,
where N is the network value,
k
the
custom scaling factor
,
d
the
custom scaling offset
, and
A the application value. When sending a value to the network, the reverse scaling is
applied. If this property is enabled, the analog values are pre-scaled from the technology to
the data point. The custom scaling is in addition to any technology-specific scaling factors
and can be applied regardless of the network technology.
10.1.8 User Registers
The device can have user registers. User registers are data points on the device that do not
have a specific technological representation on the control network. Thus, they are not
accessible over a specific control network technology.
A user register usually serves as a container for intermediate data, persistent parameters, or
data points which need to be accessed by other devices via global connections or OPC. The
register can have the following, basic data types:
Double
: A register of base type
double
is represented by an
analog
data point. It
can hold any scalar value. No specific scaling factors apply.
Signed Integer
: A register of base type
signed integer
is represented by a
multi-
state
data point. This register can hold a set of discrete states, each identified by a
signed stats ID.
Boolean
: A register of base type
Boolean
is represented by a
binary
data point.
This register can hold a Boolean value.
String
: A register of base type
string
is represented by a
string
data point. This
register can hold a variable-length character string in UTF-8 format.
Variant
: A register of base type
variant
is represented by a
user
data point. This
register can hold any user-defined data of up to a specified length of Bytes. This
length is defined when creating the register and cannot be changed at run time.
Since a register has no network direction, it can be read and written. Therefore, two data
points are generated for each register, one for writing the register (output) and one for
reading the register (input). A suffix is added to the register name to identify the respective
data point. For example, the register
MyValue
will have two data points connected to it:
MyValue_Read
and
MyValue_Write
. If supported by the device firmware, the user can
