Siemens S7-300 appendix Plc, Pno

Glossary

suitable basic factory setting which can be customized in STEP 7. There are static and dynamic parameters

Parameters, dynamic

Unlike static parameters, you can change dynamic module parameters during runtime by calling an SFC in the user program, e.g. limit values of an analog signal input module.

Parameters, static

Unlike dynamic parameters, static parameters of modules cannot be changed by the user program. You can only modify these parameters by editing your configuration in STEP 7, for example, modification of the input delay parameters of a digital signal input module.

PC station

See SIMATIC PC Station

PG

See Programming device

PLC

Programmable controllers (PLCs) are electronic controllers whose function is saved as a program in the control unit. Therefore, the configuration and wiring of the unit does not dependend on the PLC function. A programmable logic controller has the structure of a computer; it consists of a CPU with memory, input/output modules and an internal bus system. The I/O and the programming language are oriented to control engineering needs.

A PLC in the context of SIMATIC S7 --> is a programmable logic controller.

See CPU

PNO

See PROFIBUS International

Priority class

The S7 CPU operating system provides up to 26 priority classes (or "Program execution levels"). Specific OBs are assigned to these classes. The priority classes determine which OBs interrupt other OBs. Multiple OBs of the same priority class do not interrupt each other. In this case, they are executed sequentially.

Process image

The process image is part of CPU system memory. At the start of cyclic program execution, the signal states at the input modules are written to the process image of the inputs. At the end of cyclic program execution, the signal status of the process image of the outputs is transferred to the output modules.

CPU 31xC and CPU 31x, Technical data Manual, Edition 08/2004, A5E00105475-05

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