Configuring Versions Of Sync/Freeze - Siemens SIMADYN D Manual

Communications configuring
Consistency
SYNC
FREEZE
3.5.1.4

Configuring versions of SYNC/FREEZE

General
Terminology
NOTE
3-50
The SYNC and FREEZE commands synchronize the inputs and outputs
of a group of slaves. The SYNPRO function block initiates these
commands and supports the consistency checking process.
The configuring engineer is responsible in guaranteeing that data is
consistent. For the SYNC/FREEZE command, this involves consistency
of data via all of the slaves involved. It goes without saying that the
consistency of the input or output data of a slave is always guaranteed.
After initiating a SYNC command, the DP master (SS52) waits for one DP
bus circulating time, so that all of the slaves have received the new
output values. The DP master then sends a SYNC broadcast telegram to
the configured slave group. All slaves of this group then simultaneously
update their buffered outputs.
Ensuring data consistency:
When configuring, it must be ensured that during a DP bus circulating
time, after a SYNC command has been initiated, that the SIMADYN D
CPUs do not change the data.
After initiating a FREEZE command, the DP master immediately
transmits a FREEZE broadcast telegram to the configured slave group.
All of the slaves of this group then simultaneously read their inputs and
buffer them. This input data is then available for the SIMADYN D CPUs
after a DP bus circulating time has expired.
Ensuring data consistency:
By suitably configuring, it should be ensured that during a DP bus
circulating time, after the FREEZE command has been initiated, that the
input data are not evaluated by the DP master.
The terminology involved with securing data consistency are explained
and various configuring versions of SYNC/FREEZE are illustrated.
• Bus circulating time
Cycle, in which the DP master (SS52) addresses all of the slaves
once. In multi-master systems, all of the masters poll their slaves. The
bus circulating time is configured using COM PROFIBUS using the
baud rate, number and type of the slaves, and is computed by
COM PROFIBUS. It can be read-out there using the menu command
Bus parameters, as "Typical data cycle time".
• Sampling time
This is the cycle in which the SYNPRO function block and the
transmit- and receive function blocks (on SIMADYN D CPUs) are
calculated. The sampling time is configured using CFC.
Bus circulating time and sampling time are independent of one another.
System- and communication configuring D7-SYS - SIMADYN D
Edition 12.2003