Dwyer MPCJR - Manual (Page 18)

ALARM TYPE AND ACTION
CAUTION: In any critical application where failure could cause expensive product
loss or endanger personal safety, a redundant limit controller is
required.
When setting an alarm value for an absolute alarm (A1t = AbS or
A2t = AbS ), simply set the value at which the alarm is to occur.
When setting the alarm value for a deviation alarm (A1t = dE o r A2t = dE), set
the difference in value from the Set Point (SP1H) desired.
Since the input for the MPCJR is driven from a transmitter, the input display can be
programmed in different ways. Regardless of the position of the decimal point, a
change of one in the right most digit is referred to as a count. For example, if there
were no decimal point selected, a change from 235 to 236 is a change of one count.
If the decimal point were selected at 0.0, a change of 23.5 to 23.6 is a change of
one count.
The following diagram (below) shows the action and reset functions for both
absolute and deviation alarms.
When setting up an alarm for deviation the deviation is set in counts. For example
if a low alarm is required to be 5 counts below the SP1H, then set A#Lo to -5. If a
high alarm is required 20 counts above the SP1H, then set A#Hi to +20. If SP1H is
changed, the alarm will continue to hold the same relationship as originally set.
When Alarm Power Interrupt, A#Pi, is programmed ON and Alarm Reset, A#rE, is
programmed for Hold, the alarm will automatically reset upon a power failure and
subsequent restoration if no alarm condition is present.
If Alarm Inhibit, A#iH, is selected ON, an alarm condition is suspended upon power
up until the process value passes through the alarm set point once. Alarm inhibit
can be restored as if a power up took place by pressing both the INDEX and
ENTER keys for 5 seconds.
17
ABSOLUTE ALARMS DEVIATION ALARMS