Watlow Electric Ramping and Profiling Microprocessor-Based Control SERIES 1500 - Manual (Page 49)

Technical Reference
Alarms
The 1500 system provides four basic alarm conditions in each of the two control
channels. They are, with mnemonic abbreviations:
Upper Process - UP Upper Deviation - Ud
Lower Process - LP Lower Deviation - Ld
A “process” alarm, you will recall, is available at an absolute process level.
A “deviation” alarm, on the other hand, is linked to the process set point. It “deviates”
with a fixed value in either a positive or negative direction from the main set point: If
the process set point changes, the deviation alarm will shift with it while maintaining
the fixed deviation.
Alarm Options
There are two specific options for the 1500 alarms. Both are set in hardware:
Event Output Option - DIP Switch #1 ON
Latching Alarm Option - DIP Switch #2 ON
(See Chapter 1 for information on how to set the DIP switches.)
Event - Alarm Output Option
The Event Output option uses Event #4, the most significant (furthest left in the
DATA display) channel event output as an alarm indicator. With this option, any of the
four alarm conditions (listed above) on a channel will activate the alarm event output.
You may use the Event #4 output signal to control your alarm device or indicator.
When any one of a channel’s alarms is triggered, the Event #4 indicator on the
Series 1500 front panel for that channel will light.
If the Event Output Alarm Option is selected, the number of events per channel in a
program step is reduced from four to three.
Latching Option
The latching option allows alarms to be “latched,” so that momentary alarms are saved
for the operator. An alarm code will flash until the operator clears it with the CLEAR
key.
In the unlatched option state (DIP Switch ##2 = OFF), if an alarm condition is no longer
present, it is not displayed for the operator. If you press the CLEAR key and the alarm
indication remains, that means that the alarm condition is still present in the system.
Alarm Entry
Enter alarm points in the CHG PARA Mode, and in the Guarded Access (GA)
submode. The alarm ranges and defautts appear in the Guarded Access Chart for
your particular unit in this section of the manual.
WARNING:
The Series 1500
alarms are not
designed as system
“safety limits.”
These alarms do not
meet the minimum
separate power
supply require-
ments for the safety
limit function. Using
them as such could
result in damage to
your equlpment and
injury to personnel.
Watlow
recommends one
Series 140 per
channel in dual
output temperature
applications. The
Series 140 is an FM-
approved and UL
recognized latching
limit control.
Alarms, Chapter 4 WATLOW Series 1500 User's Manual 49