Occupancy Mechanisms - Siemens SIMATIC PCS7 Manual

Batch control
5.3.3 Equipment allocation procedure
Overview
Equipment
occupancy when a
batch starts and
ends
Occupancy
mechanisms
5-22
During batch execution it is guaranteed that only a single batch uses an
apparatus at any one time. To this end, batch control checks equipment
allocations every time a batch starts and finishes and every time every AF in
the control recipe starts and finishes:
A batch cannot therefore be started unless the apparatuses the batch requires
are free at the beginning of the batch. It does not matter here whether the
batch is started automatically or by direct action on the part of the user.
The case where the batch is to be started and a decision be made later on
about which apparatus is to carry out further processing of the batch can be
catered for in the recipe structure by inserting 'OR' branches for different
apparatuses.
The occupancy mechanisms ensure that different batches do not
simultaneously seize the same apparatus and that different control recipe
automation functions do not simultaneously access the same AF interface
block. To this end, the occupancy mechanisms should perform the following
actions when the batch starts or ends and when the AF starts or ends:
Table 5-8

Occupancy mechanisms

Occasion
Batch start
Batch end
AF start
AF end
If an apparatus or an AF has not been released for use by BATCH flexible, an
error message will be issued and the batch is paused.
Action
– Check equipment occupancies
– Start batch
– Release occupied apparatuses
– Check apparatus occupancy and reserve
equipment
– Check AF occupancy and reserve
– Write AF setpoints
– Start AF
– Read AF setpoint and actual values
– Release AF
– Release apparatus (if requested)
Batch flexible , Manual
C79000-G7076-C650-02