Failure Behavior Of The Batch Server In As-Based Mode; Configuration Limits; Definition Of Configuration Limits - Siemens SIMATIC BATCH Operating Manual

Product introduction and installation

3.6 Configuration limits

3.5.5.10

Failure behavior of the BATCH server in AS-based mode

Failure of the BATCH server
In AS-based mode, batches are processed in the CPU. If the BATCH server fails, any batches
that have started are processed to the end if the BATCH server does not need to intervene in
the recipe execution, for example for synchronization or due to an operator dialog. Otherwise,
the individual units used in the control recipe continue to the next synchronization line and then
wait for communication with the BATCH server.
The situation still remains that if there is a sudden failure of the SIMATIC BATCH standby PC
(hardware defect, power failure, network connection to the database broken down), the BATCH
server can no longer store the AS frames in the database of the standby PC (redundant storage
for data backup/replication). The timeout time for recognizing the failure is set to 20 seconds
for technical reasons. If more frames are generated in the AS within these 20 seconds than
the internal AS buffer can store, the batches currently running on the AS change to the "Held"
status. This default setting can be changed for specific units in the AS.
Additional information is available in the manual SIMATIC BATCH Blocks V8.0 > Interface
blocks > BATCH interface blocks > UNIT_PLC > Command interface for influencing the entire
unit.
Temporarily storing events in the AS in the buffer memory
If the communication from the AS to the BATCH server breaks down or the server itself fails,
batch processing in the automation system continues until the next synchronization line or to
the end of the batch. This is also the response in a redundant scenario during the failover
phase and in the event of both BATCH servers failing. The corresponding events (the number
depends on the size of the AS memory) are stored temporarily in the AS until they are fetched
by the runtime component of the BATCH server.
When the buffer is full, the AS sends a message to the PCS 7 OS. You can use a parameter
on the UNIT_PLC block to specify whether the control recipe should continue to run or whether
the unit should switch to a previously defined state.
Additional information is available in the manual SIMATIC BATCH blocks V8.0> Interface
blocks > BATCH interface blocks > UNIT_PLC > Settings for communication monitoring and
for the communication buffer.
3.6 Configuration limits
3.6.1

Definition of configuration limits

Definition
The quantity structure in SIMATIC BATCH describes the quantitative load on the process
control system when executing batch processes. A distinction is made between the quantity
structure for AS-based and PC-based modes.
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SIMATIC BATCH V8.2
Operating Manual, 02/2016, A5E35958174-AA