Siemens SIMATIC NET Manual de Serviço descarregar pdf (Página 33)

Glossary

Introduction to PROFIBUS on Industrial PC

C79000-G8976-C068

Collection of data that may be distributed within the programmable

logic controller (for example flags/memory bits or data blocks) to be

transferred using the -> global data technique.

A GD group is a group of -> stations that exchange global data with

each other. A -> GD packet is sent to the stations belonging to the GD

group.

Global data (GD) is the name of a communication technique for the

cyclic exchange of limited amounts of data from STEP 7 data areas

between CPUs of the S7-300/400. Transmitted data can be received

by several CPUs at the same time.

Part of the I/O area of SIMATIC S5 PLCs can be used for global data

exchange between SIMATIC S5 PLCs on -> PROFIBUS. The main

characteristic of this technique is the cyclic transmission of data that

have changed since the last cycle.

DP slaves can be assigned to one or more groups using a group

identifier. The -> control frames can be addressed to specific groups of

DP slaves using the group identifier.

A -> bus parameter for -> PROFIBUS. This specifies the highest ->

PROFIBUS address (HSA) of an active -> station on the PROFIBUS

bus. PROFIBUS addresses higher than the highest station address are

possible for passive stations (possible values: HSA 1 to 126).

An active station in -> PROFIBUS that can send -> frames on its own

initiative when it is in possession of the token.

A -> bus parameter for -> PROFIBUS. The maximum station delay

(max. TSDR) specifies the longest interval required by a -> station in

the -> subnet between receiving the last bit of an unacknowledged ->

frame and sending the first bit of the next frame. After sending an

unacknowledged frame, a sender must wait for the max. TSDR to

elapse before sending a further frame.

A -> bus parameter for -> PROFIBUS. The minimum station delay

(min. TSDR) specifies the minimum time that the receiver of a ->

frame must wait before sending the acknowledgment or sending a new

frame. The min. TSDR takes into account the longest interval required

by a station in the subnet for receiving an acknowledgment after

sending a frame.

A network consists of one or more interconnected -> subnets with any

number of -> stations. Several networks can exist side by side. There

is a common -> node table for every -> subnet.

GD packet

GD group

Global data

Global I/Os

Group identifier

Highest

PROFIBUS

address

Master

Maximum

station delay

Minimum

station delay

Network

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