Optimum Installation Of The Blocks For As-Based Mode; Structure Of The Unit With The Unit_Plc Interface Block - Siemens SIMATIC BATCH Operating Manual

Engineering
7.1 Basic engineering for PCS 7
7.1.4.2

Optimum installation of the blocks for AS-based mode

Block execution in AS-based mode
The entire recipe control in this mode is controlled by the UNIT_PLC block. To achieve optimum
step change times, the following rules must be kept to:
1. The UNIT_PLC block and SFC type, IEPH/SFC, IEOP/SFC must be installed in the same
OB. If this is not the case, the recipe unit can nevertheless be executed but the step change
cannot be made in the same cycle.
2. Order in which the blocks are called:
– Block calls for a recipe phase or a recipe operation (SFC type or IEPH/IEOP/SFC)
– Call for blocks that represent an actuator (for example: VALVE or MOTOR)
– Call for blocks for controlling the actuators (driver blocks)
– Call for the blocks for the unit UNIT_PLC
7.1.4.3

Structure of the unit with the UNIT_PLC interface block

The following functions are executed by the BATCH interface block UNIT_PLC:
● Assigning and releasing a unit using a running control recipe.
● Control of the recipe unit procedure in AS-based mode
The UNIT_PLC block manages a unit
Each UNIT_PLC block manages precisely one unit in the automation system. This block is the
central block for batch control. The following rules apply when inserting the block:
● To map the unit on the AS, there must be exactly one instance of the UNIT_PLC block in
one of the charts of the "Unit" hierarchy folder.
● There are no other settings or interconnections necessary for UNIT_PLC.
● At the "UNIT_NAME" input of UNIT_PLC, the unit name that was defined in the plant
hierarchy is always shown. The "UNIT_NAME" input cannot be modified in the block.
Every recipe operation (ROP), equipment phase (EPH) or transition in the assigned unit is
checked by this block and the specifications for further processing steps are defined.
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Note
Call from OB 32
Due to the AS cycle time, we recommend you insert all Batch-relevant blocks into OB32
(AS update cycle = 1 sec.). Faster processing does not result in shorter step change
times.
If you need the recipe phases to run faster/slower as 1 second due to the process
situation, you can also insert the Batch-relevant blocks in a faster/slower OB. Make sure
that the UNIT-PLC block does not exceed the OB cycle time when running the recipe
unit procedure.
SIMATIC BATCH V8.2
Operating Manual, 02/2016, A5E35958174-AA