Siemens 353 User Manual page 83

UM353-1B
Alarms have priorities 1 to 5, with 1 the highest. Alarms are reported to the operator faceplate in order of priority
first and then in order of occurrence. Priority 1 causes the station bargraphs and condition (e.g. A1 HI) to flash and
requires acknowledgment to stop flashing. Priority 2 also flashes the bargraphs and condition but stops flashing
when the alarm clears (i.e. Self Clearing). Priority 3 causes the event LEDs (L and S) and condition to flash.
Flashing stops only when the alarm is acknowledged. Priority 4 causes the event LEDs and condition to flash but
flashing stops when the alarm clears. Priority 5 displays the alarm but does not require that it be acknowledged.
Alarm limits are in engineering units. A quickset ALARM feature is also available allowing alarm limits to be set
quickly during operation. The settings are in engineering units but will also be displayed in % of range on the
setpoint bargraph when viewing a point. Alarms are displayed as defined by the range pointer parameter. Alarms
can be set to any engineering value within -10% to 110% of the range defined by the pointer. If a range is changed,
the current alarm settings will be changed to be the same % within the new range. For example, if a HI alarm is
currently set at 100.0 with a range of 0.0 to 100.0 and the range is changed to 300.0 to 400.0, the HI alarm will be
moved to 400.0.
Each alarm can be enabled or disabled when in the quickset ALARM mode. The configuration allows an alarm to
be enabled or disabled on a cold start. When an alarm is disabled, it will not operate but will retain settings for
return to the enabled mode. Operator faceplate functions, relating to alarms, are described in the sections describing
the specific faceplate controls and displays. All alarms have the following features:
Deadband - requires that the signal either drop below or exceed the limit setting by the amount of the deadband
before the alarm clears (goes low). The alarm deadband is set as a fixed % of the range pointer scale.
Delay-In Time - requires that the input remain above (or below) the limit setting for the delay time before the alarm
trips (goes high). This can help prevent nuisance alarms that may be tripping due to process noise.
Delay-Out Time - requires that the input remain below (or above) the limit setting plus deadband for the delay time
before the alarm will clear (goes low). This can help prevent inadvertent clearing of alarms due to process noise.
Ringback - causes a previously acknowledged alarm to require acknowledgment (priorities 1-4) when the alarm
clears.
i|ware PC Faceplate Display
April 2012
AnDisp1
4 2 3. 4 5
2
.1
T I 2 4 3 5
Process
UNITS
Process DPP
R1
R1
P1
Process
Engineering
INput units
scaling
R1
P2
D
P3
.4
R1
Process
UNITS
Process DPP
R4
R4
P4
Process
Engineering
INput units
scaling
R4
BLOCK DIAGRAM
Function Blocks
<loop tag>
<process 1 digital value>
<process 1 tag name>
d e g F
P <process 1 units>
UNITS
1A
1B
Process 1 Alarms
2A
2B
Process 2 Alarms
3A
3B
Process 3 Alarms
4A
4B
Process 4 Alarms
LE
Station & Loop Error Handling
SE
3-53