Function Blocks
ALM Alarm Function Block
Revision 11 HC900 Hybrid Control Designer Function Block Reference Guide 51
2/07
ATTENTION
Local Setpoint is set in the Hybrid Control Designer unless “Use RSP Input” is enabled. Use
an Analog Variable connected to one RSP input (use RSP Input Enabled) if you want to
change alarm setpoint at the operator interface via the Variable Edit Display.
Table 16 Analog alarm configuration parameters
Parameter
Index
#
Parameter Description Value or Selection
Block Order
N/A Execution Order for Block
Read Only. To change block order,
right-click on a Function Block and
select Execution Order.
Alarm
Setpoint
Type
N/A Alarm Action Type PV>SP = High Process Variable/Local
Setpoint
PV>CV = High Process Variable
/Compare Value
PV<SP = Low Process Variable/Local
Setpoint
PV<CV = Low Process Variable
/Compare Value
(PV-CV)>SP = High Deviation Alarm
(CV-PV)>SP= Low Deviation Alarm
IPV-CVI>SP = Band Absolute
Deviation Alarm
Hysteresis
4
Hysteresis in engineering units can
be set from 0 to the input span
monitored variable.
0 to 99999.9 in Engineering Units
Local
Setpoint
0
Local Setpoint value in engineering
units or a calculation from another
function block via RSP (see “Use
RSP Input”).
0 to 99999.9 in Engineering Units
Use RSP Input
1 Remote Setpoint selection
Click on box to use Remote Setpoint
(RSP).
Output Latch
3
ON latches the alarm output until
acknowledged.
To acknowledge an alarm, it must
be tagged and entered into an
alarm group. This will provide for
the acknowledgment from the
operator interface.
Click on Box to select.
On Delay
6
Number of seconds the alarm is
active before activating OUT.
0 to 240 seconds
Examples
HFigure 10/Example 1 shows an ALM function block being used for Band Deviation Alarm—a control loop
process variable is compared to the loops working setpoint. A variable is used as the setpoint value to allow
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