User Manual
Control concept
Local control design
5
70 | 353 CM110664en_07
The runtime of a damper or the coasting time for a multi-speed motor can be
defined in table [TbTiDly] to display or evaluate a transient state [TraSta]. The
time parameter can also influence the switching response depending on the
switch kind [SwiKind] used.
Plant fault
The block independently recognizes faults and reports them to the defined
alarm class [AlmCl], which for its part is responsible for distributing the alarms
to alarm receivers. Depending on the alarm function [AlmFnct] set in the block,
you may have to acknowledge the alarm and reset it after eliminating the alarm.
The faulted block on output [Dstb] is reset only after the user action is run. The
plant ramps up only after an alarm reset since both the local control, as a rule,
with this output is blocked for a fault and as superposed control triggered a
plant fault.
The alarm reset can be triggered:
● By triggering a common reset in the common alarm block CMN_ALM
● Via an alarm client
5.2 Local control design
Fault-related shutdown
The disturbance output [Dstb] for an I/O function block is activated when the
block recognizes a FAULT alarm (e.g., broken wire) or an OFFNORMAL alarm
(e.g., exceeding a limit value).
The following figure shows how a valve and a pump are forcibly shut down or
ramped up depending on the fault state.
Example forced set-up
A limit value [HiLm] is defined for the temperature in block AI Temp. As soon as
this threshold is reached, the output [Dstb] switches the valve via Enable
[EnSfty] for the analog output value to 100%. At the same time, the pump is
switched to off by Enable [EnSfty] for the Binary Output BO.
Example of fault-related shutdown
The block BI ThOvrld monitors the state of the pump’s thermal switch. If the
contact is triggered, the function block is activated based on the parameterized
reference value [RefVal] for [Dstb] output. The pump is shutdown through
Enable [EnSfty] of the Binary Output BO. The Binary Output BO further
monitors the contact’s feedback. In the event of a fault, where the feedback is
interrupted, e.g., the block reports the fault and shuts down itself via the back
P15 Pgm P4 Crit
PrVal
FbVal
Dstb
CritActv
TraSta
P15 Pgm
P4 Crit
P
r
V
a
l
F
b
V
a
l
D
s
t
b
C
r
i
t
A
c
t
v
T
r
a
S
t
a
Temp:
AI
OR
100
%
Pu
Cp: BO