<9. Advanced Engineering >
9.1.9 Specifying Retain Data and OPC Property
Variables used in Logic Designer are, by default, neither specified as retain data nor
specified with OPC property.
To configure a variable as retain data or to access a variable from other equipment
using the OPC function requires the variable to be explicitly specified as retain data
and specified with OPC property.
● Procedure for Specifying Retain Data and OPC Property
A variable can be specified as retain data or specified with OPC property either from
the Variable Properties dialog or the variable worksheet.
The left figure below shows the Variable Properties dialog while the right figure
below shows the variable worksheet. In either case, ticking the RETAIN (or Retain)
checkbox or OPC checkbox displayed within blue boxes specifies the corresponding
variable as retain data or adds the OPC property to the variable.
● Parameters of NPAS_POUs
Access parameters and engineering parameters of NPAS_POUs are specified as
retain data and specified with OPC property within the system.
Hence, all these parameters can be treated as retain data and data with OPC
property without need of any setup.
● Specifying Retain Data and OPC Property for User-defined Variables
Variables of user-defined data types can also be specified as retain data or specified
with OPC property.
However, a large array of a user-defined data type cannot be specified as retain
data if the array size exceeds 32768 bytes.
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