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Section 4 Analog Process Control
Signal Handling
Split-Range Controller
A split-range controller is constructed as a combination of the following control
modules: input and output modules, a controller module and any of the branching
modules. The output from a controller is then divided into two ranges which can be
set independently, and may overlap each other. An example of the use of split-range
control is when two control valves are used. The valves may be of different sizes
working in the same direction. The lower range is connected to the smaller valve
and when it is fully open, the upper range opens the larger valve. The valves may
also work in opposite directions. For example, when a tank level is to be controlled.
At lower levels, one valve opens, and at higher levels, the other valve opens.
Sp
Pv
Analog
Output
PID
controller
Output
Split-
range
Analog
Output
Figure 81. Example of split-range control where the output range from the
controller is divided into two branches with different ranges
Signal Handling
The Control libraries contain a number of function blocks and control modules for
signal handling. There are also types for signal handling in the Basic and Signal
libraries.
For a list and description of available signal handling objects, see Advanced
Functions on page 176.
Control Builder online help also contains additional information on specific
signal handling objects. Select the object in Project Explorer, and press F1 to
display online help for a type.
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