Rockwell Automation T3834 ICS Regent Continuous Control Package for Winterpret - Manual (Page 3)

Continuous Control Package for W INTERPRET (T3834)
P D - 6 0 4 4 M a r c h , 0 6
3
Shared variables are data values internal to the Regent
that may be commonly referenced by all function blocks of
any application program. Use the Shared Variable Editor
to define the shared variables in the Regent.
Each controller may have up to 10 alarms associated with
it, each of which may be defined by assigning a name.
Continuous Control is used to maintain a measured
process signal at a predetermined value. A Continuous
Control process requires four fundamental items:
· A process variable (PV) that can be measured
· A setpoint (SP) at which the process variable should be
maintained
· A control output that affects the process such that the
process variable is changed
· A set of rules that govern how the controlled output
should be changed to make the process variable equal to
its setpoint
Most of the parameters in the Continuous Control loop
may be assigned a name instead of a constant value.
When a parameter is given a name, that value may be
dynamically modified by other application program
function blocks.
Examples of how this dynamic modification might be used
include:
· Assigning a name to the auto/manual parameter would
enable a ladder logic function block to place the
Continuous Control loop in automatic mode when
required by the process
· Assigning a name to the setpoint parameter would
enable a ladder logic function block to modify the
setpoint automatically. Remote setpoint and ramp/soak
functions could be initiated automatically based upon
sequential process events.
· Continuous Control alarms can be assigned names to
enable them to be referenced in ladder logic function
blocks