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Siemens Simatic S7-400 User Manual

Page 611

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Glossary

Glossary-5

S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07

Direct communication

Direct communication involves assigning local input address areas of an
intelligent DP slave (for example, CPU 315-2 with PROFIBUS DP connection) or
of a DP master to the input address areas of a PROFIBUS DP partner. The
intelligent DP slave or DP master receives the input data that the PROFIBUS DP
partner sends to its DP master via these assigned input address areas.

DP master

A node with a master function in the PROFIBUS DP. A master that behaves in
accordance with the EN 50170 with the DP protocol is a DP master. The bus
access right (token) is only passed amongst masters. The slaves, in this case DP
slaves, can only respond on the request of a master. The following distinctions
are made:
DP master (class 1): executes the user data communication with the DP slaves
assigned to it.
DP master (class 2): provides services such as: reading of the input/output data,
diagnostics, global control.

DP slave

A

³

slave that is operated on the PROFIBUS bus system with the

PROFIBUS DP protocol is called a DP slave.

Edge, falling

Signal status change from 1 to 0

Edge, rising

Signal status change from 0 to 1

EEPROM

Electrically erasable programmable read-only memory

EPROM

Erasable programmable read-only memory

Equidistance

Equidistance is a DP bus cycle that is accurate to a few

m

s and can be configured

in STEP 7.

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