User Manual
Control concept
Local control design
5
CM110664en_07 71 | 351
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
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