Siemens NAN 67 Series Manual de servicio descargar pdf (Pagina 300)

Glossary-6

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

C79000-G7076-C504-02

A logic string is that portion of a user program which begins with an FC bit

that has a signal state of 0 and which ends when an instruction or event resets

the FC

bit to 0. When the CPU executes the first instruction in a logic string,

the FC

bit is set to 1. Certain instructions such as output instructions (for

example, Set, Reset, or Assign) reset the FC

bit to 0. See First Check Bit

above.

The Master Control Relay (MCR) is an American relay ladder logic master

switch for energizing and de-energizing power flow (current path). A

de-energized current path corresponds to an instruction sequence that writes a

zero value instead of the calculated value, or, to an instruction sequence that

leaves the existing memory value unchanged.

A CPU in the SIMATIC Manager has three memory areas:

S Load memory

S Work memory

S System memory

A type of addressing in which the address of an instruction indicates the

location of the value with which the instruction is to work.

Mnemonic representation is an abbreviated form for displaying the names of

addresses and programming instructions in the program (for example, “I”

stands for “input”). STEP 7 supports the international representation (based

on the English language), and the SIMATIC representation (based on the

German abbreviations of the instruction set and the SIMATIC addressing

conventions).

The nesting stack is a storage byte used by the nesting instructions A(, O(,

X(, AN(, ON(, XN(. A total of eight bit logic instructions can be stacked.

Networks subdivide LAD blocks into complete current paths.

Logic String

Master Control

Relay

Memory Area

Memory Indirect

Addressing

Mnemonic

Representation

Nesting Stack

Network

Glossary

1 2 ... 295 296 297 298 299 300 301 302 303 304 305 ... 317 318

Comentarios a estos manuales

Sin comentarios

Siemens NAN 67 Series Manual de servicio Pagina 300

Comentarios a estos manuales

Relacionado con productos y manuales para Placas Siemens NAN 67 Series