Watlow Series 982 - Manual (Page 113)

from set point. The operator can enter independent high and low alarm set-
tings. The reference for the deviation alarm is the set point. Any change in set
point causes a corresponding shift in the deviation alarm. Low alarms are set
at a negative deviation while high alarms are a positive deviation.
Example : If your set point is 100°F and a deviation alarm is set at +7°F as the
high limit, and -5°F as the low limit, the high alarm trips at 107°F, and the
low alarm at 95°F. If you change the set point to 130°F, the alarms follow the
set point and trip at 137°F and 125°F.
A rate alarm alerts the operator when the process monitored by Input 1 is
increasing at a rate higher than that set by AXHI or decreasing at a rate lower
than that set by AXLO. The rate is sampled once a second.
Alarms can be latching or non-latching. When the alarm condition is removed,
a non-latching alarm automatically clears the alarm output and alarm mes-
sage, if one is present. You must manually clear a latching alarm before it will
disappear.
An alarm is indicated by the corresponding LED on the front panel, L2, L3 or
L4. There may be an alarm message flashing in the lower display, but if the
Anun prompt is set to OFF (located in the Global menu), no alarm message is
displayed. When an alarm message is displayed, it alternately flashes with the
current prompt at a 1 second interval in the lower display.
To clear a latching alarm, first correct the condition then press the Hold/Run
key once.
Alarm silencing is available with all alarms. This function overrides the
alarm on initial power up. On power up, the alarm message is masked and the
appropriate L2, L3 or L4 LED and output reflect a non-alarm condition. The
silencing is active until the process has entered the safe region located
between the low and high alarm settings. Any future deviation outside this
safe region triggers an alarm. If an alarm occurs at this point, the output can
be silenced by pressing the Hold/Run key once, but the alarm message is still
displayed.
Error Code E1 and E2 Messages
Four dashes, “- - - -”, in the upper display indicate a Series 981/982 error.
The lower display will indicate the error code. The controller will be in the
Hold mode with both control outputs off. The alarm outputs will be in their
alarm state and the associated LED lit.
EX 1: A/D underflow error
The Input X A/D circuit is underrange. An open or reversed polarity sensor is
the most likely cause. Check the sensor; if the connection is good, and func-
tions properly, call the factory. Make sure the InX prompt matches your sen-
sor.
EX 2: Sensor underrange error
The Input X sensor generated a value lower than that allowed for the range of
the sensor, or the A/D circuitry malfunctioned. Enter a valid input. The A/D
WATLOW Series 982 User’s Manual
8.5 Tuning, Alarms and Error Codes, Chapter 8
Alarms
˜
NOTE:
An alarm display
will be masked by
an error condition
or when the con-
troller is in the
Calibration or
Setup menus.
˜
NOTE:
An X applies to
Alarm 2, 3 or 4.
˜
NOTE:
An X applies to
input 1 or 2.