Siemens S7-300 Nesting depth, Network, Non-isolated, OB priority, Operating state, Parameters

Glossary

Nesting depth

A block can be called from another by means of a block call. Nesting depth is referred to as the number of simultaneously called code blocks.

Network

A network is a larger communication system that allows data exchange between a large number of nodes.

All the subnets together form a network.

A network consists of one or more interconnected subnets with any number of nodes. Several networks can exist alongside each other.

Non-isolated

The reference potential of the control and on-load power circuits of non-isolated I/O modules is electrically interconnected.

OB

See Organization blocks

OB priority

The CPU operating system distinguishes between different priority classes, for example, cyclic program execution, process interrupt controlled program processing. Each priority class is assigned organization blocks (OBs) in which the S7 user can program a response. The OBs are assigned different default priority classes. These determine the order in which OBs are executed or interrupt each other when they appear simultaneously.

Operating state

SIMATIC S7 automation systems know the following operating states: STOP, START, RUN.

Operating system

The CPU OS organizes all functions and processes of the CPU which are not associated to a specific control task.

See CPU

Organization blocks

Organization blocks (OBs) form the interface between CPU operating system and the user program. OBs determine the sequence for user program execution.

Parameters

1.Variable of a STEP 7 code block

2.Variable for declaring module response (one or several per module). All modules have a

Glossary-12

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