Siemens CP-8000, Руководство пользователя

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Function Packages
SICAM A8000 / CP-8000 • CP-8021 • CP-8022 Manual Unrestricted
65
DC8-037-2.02, Edition 10.2017
Functions for priority channels:
•
State compression for measured values (can be set using parameters) for the reduction of
the flood of messages, that can continuously generate fluctuating measured values
•
Behavior with a priority channel overload
•
Behavior during a communication failure (transmit direction)
•
Monitoring of the dwell time (parameter-settable) of
messages with process information
in
control direction
Messages that are stored too long in the priority channel are discarded
•
Answering of station interrogations
•
Behavior during failure of I/O Master Modules, communication interfaces etc.
•
Blocking (series of information elements)
3.2.1.4 Priority Control
The priority controller has the task of selecting messages recorded in the data memories in-
dependently and individually for each interface and station, and to direct the transmission of
the messages via the protocol elements in accordance with their priority. This ensures that
with simultaneous existence of several active information items, the higher-priority, highly im-
portant information is transmitted first.
The prioritization does not however represent an absolute priority status, but rather a measure
for dividing up the channel capacity. This ensures that even with continuously available high-
er-priority data, those of lower priority can also be transmitted.
3.2.2 Communication within the Automation Unit
Within the automation unit, the function package Telecontrol communicates with the function
package
Automation
via its Telecontrol Interface .
3.2.3 Protocol Element Control and Return Information
This function is used for the user-specific influencing of the functions of the protocol elements.
The main application lies with protocol elements with multi-point data communication mode
and especially for dial-up traffic configurations.
This function contains two separate independent parts:
•
Protocol element control
─
Test if stations are reachable
─
Suppression of errors with intentionally switched-off stations
•
Protocol element return information
─
Cost control of telephone charges
─
Cost-efficient utilization of the telephone line
(for instance command initiation only if a connection has already been established)