Siemens CP-8021 User Manual

Function Packages
70 Unrestricted SICAM A8000 / CP-8000 • CP-8021 • CP-8022 Manual
DC8-037-2.02, Edition 10.2017
3.3.2 Open-/Closed-Loop Control Function
The open-/closed-loop control function is used for the management of automation tasks with the
help of a freely programmable application program.
The creation of the application program is carried out by the SICAM TOOLBOX II with the tool
CAEx plus predominantly in function diagram technology according to IEC 61131-3. Alterna-
tively, the application program can be created as instruction list with an ASCII editor.
The application program processes process information (so-called signals) from the connect-
ed I/O Modules and/or from other system elements in the automation network of the specific
process-technical plant.
Process images form the interface of the application program to the outside world. It is distin-
guished between input process images and output process images.
The exchange of the process information can take place in two ways:
• Transmission of periodical information objects from and to the I/O Master Module (process
data input and output)
• Transmission of spontaneous information objects from and to functions within the automa-
tion unit, other automation units or control systems via the telecontrol interface
3.3.2.1 Non-Volatile Storage
Variables, signals (input process images for spontaneous information objects) and function
blocks can be saved non-volatile. That means, that after a power failure these variables and
signals are immediately available again with their values before the power failure.
3.3.2.2 Task Management
The open-/closed-loop control function manages the application program in a periodically run-
ning task.
Coordination of the Sequences of a Task
• Periodical start in the selected cycle
• Programmable single-run upon change of a signal from the communication or from the
I/O Modules (no hardware interrupt)
• Input handling
• Program processing
• Output handling
Cycle Time
• Within the cycle time, the application programs must process the input handling and the
output handling
• The cycle time can be set in the application program

Siemens CP-8021 Specifications

General

Brand	Siemens
Model	CP-8021
Category	Controller
Language	English