Siemens S7-300 appendix Proxy, Real Time, Reduction factor, Reference ground, Reference potential

Glossary

Proxy

The PROFINET device with proxy functionality is the substitute for a PROFIBUS device on Ethernet. The proxy functionality allows a PROFIBUS device to communicate not only with its master but also with all nodes on PROFINET.

You can integrate existing PROFIBUS systems into PROFINET communication, for example with the help of an IE/PB Link or a CPU 31x-2 PN/DP. IE/PB LinkThe IE/PB Link then handles communication over PROFINET as a substitute for the PROFIBUS components.

See PROFINET Device

RAM

Work memory is a RAM memory in the CPU which is accessed by the processor during user program execution.

RAM (Random Access Memory) is a semiconductor read/write memory.

Real Time

Real time means that a system processes external events within a defined time. Determinism means that a system reacts in a predictable (deterministic) manner.

In industrial networks, both these requirements are important. PROFINET meets these requirements. PROFINET is implemented as a deterministic real-time network as follows:

•The transfer of time-critical data between different stations over a network within a defined interval is guaranteed.

To achieve this, PROFINET provides an optimized communication channel for real-time communication : Real Time (RT).

•An exact prediction of the time at which the data transfer takes place is possible.

•It is guaranteed that problem-free communication using other standard protocols, for example industrial communication for PG/PC can take place within the same network.

Reduction factor

The reduction rate determines the send/receive frequency for GD packets on the basis of the CPU cycle.

Reference ground

See Ground

Reference potential

Voltages of participating circuits are referenced to this potential when they are viewed and/or measured.

Repeater

See Hub

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

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