SIMATIC Industral Software - Tools for configuring and programming ...

Modular PID control
SIMATIC controllers are suitable for use in all sectors.
They can be used for open and closed-loop control tasks.
The controls can be complex and extensive. In some cases,
however, they can also consist of only a few arithmetic
blocks. Regardless of the size of the controller the main
requirement is mostly to reduce memory space. Scalability
and flexibility can be achieved with modular solutions.
Modular PID control is suitable for configuring modular
controls based on the modular design principle.
Modular PID control comprises two components: a parameterization
tool as an option for STEP 7 and control blocks for the
CPU.
Modular PID Control with the graphical function diagram editor CFC
The main fields of application for modular PID control are
process-oriented plants with high control requirements.
Functions
The library with function blocks for SIMATIC S7/C7 and WinAC
permits the following controller types to be implemented:
■ Continuous-action PID controllers
■ Pulse controllers
■ Step controllers
The following ready-to-use examples are included in the scope
of supply:
■ Fixed value controller with different outputs
■ Single-loop and multi-loop ratio controller
■ Mixture controller
■ Cascade controller
■ Controller with pre-control and feedforward control
■ Range selection controller
■ Alternating controller
■ Multi-variable controllers
The blocks can be linked with STEP 7, SCL and CFC. CFC is
particularly suited for configuring complex controller structures
clearly and reliably in a short time. If modular PID control
is used in conjunction with the SIMATIC SM 334 analog module
scan times of less than 5 ms can be achieved.
Controller optimization and test functions are contained in the
Standard PID Control package.
PID Self-Tuner
Correct adjustment of a controller requires extensive experience.
The parameterization tools standard PID control and
modular PID control have a self-tuning function. In this way,
they offer the user effective support with setting the programming
device/PC. If conditions change during operation the
controller must be optimized again. The PID self-tuner is runtime
software which performs automatic online optimization
without the need for a programming device/PC.
PID self-tuner is a function block with which PID or PI controllers
can be set online and adapted during operation.
PID self-tuner is especially suited for optimizing temperature
controllers, level controllers and flow controllers.
Controller optimization of standard PID control with PID self-tuner
Control configuration 17