Siemens NAN 67 Series Wartungshandbuch PDF herunterladen (Seite 302)

Glossary-8

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

A container for user programs, source files, and charts for S7 programmable

controllers. The S7 program also includes the symbol table.

A shared data block is a DB whose address is loaded in the DB address

(FC, FB, or OB) that are being executed.

In contrast, an instance DB is designed to be used as specific storage and data

for the FB with which it has been associated.

The SIMATIC Manager is the graphical user interface for SIMATIC users

under Windows 95.

A source file (text file) is part of a program created either with a graphic or a

textual Editor and is compiled into an executable S7 user program or the

machine code for M7.

An S7 source file is stored un the “Sources” folder in the S7 program.

A statement is the smallest independent part of a user program created in a

textual language. The statement represents a command for the processor.

Statement List is a textual representation of the STEP 7 programming

language, similar to machine code. STL is the assembler language of STEP 5

and STEP 7. If you program in STL, the individual statements represent the

actual steps in which the CPU executes the program.

A station is a device which can be connected to one or more subnets, for

example the programmable controller, programming device, operator station.

The status bit stores the value of a bit that is referenced. The status of a bit

instruction that has read access to the memory (A, AN, O, ON, X, XN) is

always the same as the value of the bit that this instruction checks (the bit on

which it performs its logic operation). The status of a bit instruction that has

write access to the memory (S, R, =) is the same as the value of the bit to

which the instruction writes or, if no writing takes place, the same as the

value of the bit that the instruction references. The status bit has no

significance for bit instructions that do not access the memory. Such

instructions set the status bit to 1 (STA=1). The status bit is not checked by

an instruction. It is interpreted during program test (program status) only.

S7 Program

Shared Data Block

(DB)

SIMATIC Manager

Source File

Statement

Statement List

(STL)

Station

Status Bit

Glossary

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