Parallel Tuning Of Control Channels - Siemens SIMATIC Manual

3.13

Parallel Tuning of Control Channels

Neighboring Zones (Strong Heat Coupling)
If two or more controllers control the temperature, for example, on a plate (in other
words, there are two heaters and two measured process values with strong heat
coupling ), follow the steps outlined below:
1. OR the two outputs QTUN_RUN.
2. Interconnect the two TUN_KEEP inputs with the output of the OR element.
3. Start both controllers by setting a setpoint step change at the same time or by
setting TUN_ST at the same time.
The schematic below illustrates the parallel tuning of controller channels.
TCONT_CP, DB1_TCONT_CP
TCONT_CP, DB2_TCONT_CP
TUN_KEEP
Advantage:
Both controllers output LMN0 + TUN_DLMN until both controllers have left
Phase 2. This avoids that the controller that completes tuning first falsifies the
tuning result of the other controller due to the change in its manipulated variable.
Caution!
Reaching 75% of the setpoint step change means that the tuning leaves Phase 2
and that the output QTUN_RUN is reset. Automatic mode starts, however only
when TUN_KEEP also changes to 0.
Neighboring Zones (Weak Heat Coupling)
As a general rule, tuning should be carried out to reflect the way in which the
control will work later. If zones are operated together during production so that the
temperature differences between the zones remain the same, the temperature of
the neighboring zones ought to be increased as well during tuning.
Differences in temperature at the beginning of the tuning are irrelevant since they
will be compensated by the initial heating (-> initial rise = 0).
PID Temperature Control
A5E00125039-02
TUN_KEEP
QTUN_RUN
QTUN_RUN
Controller Tuning in FB 58 "TCONT_CP"
≥
1
3-19