Instruction Manual

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AN-T80009 Trusted
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Intelligent Online Updates
Issue 4 Nov 08 AN-T80009 15
1.10. Supported Changes
Intelligent Updates support a number of changes that are not possible with Normal Updates. The full
extent of what can be changed is detailed below. Refer to sections 1.12 and 1.13 for details of some
common implications of these rules.
1.10.1. Variables
CAN add a new variable.
CAN delete an existing variable.
CAN change a variable’s attributes (internal, input, output, or constant).
CAN change a variable’s initial value.
CAN change a variable’s retain setting.
CAN change a variable’s extended attributes.
CAN change a variable’s Modbus address.
CAN change a variable’s comment.
CAN change a variable’s name, but it’s value will not be preserved.
CAN change an analogue variable’s format (integer, real), but it’s value will not be preserved.
If a new input or output variable is added, or an existing variable is redefined as an input or output type,
the variable must be connected to a previously defined I/O board or the project will not successfully
compile.
The current value of any new or redefined inputs will not be preserved across an update (it will assume
the ‘input’ value on the first scan after the update).
Only new variables will assume their initial values on an update.
Retained variables are not available once the update has been realized. They become available again
after the initial post-update scan.
Changing a variable’s name will have the same effect as deleting the original variable, then adding the
new one. The value of the variable will not be maintained across an update.
Changing an analogue variable’s format from integer to real (or vice-versa) will have the same effect
as changing the variable’s name (i.e. the value of the variable will not be preserved across an update).
Unless stated otherwise, variables maintain their values across an update.