Watlow CLS200, MLS300 and CAS200 - Manual (Page 56)

50 Communications Specification
Chapter 3: Controller Parameter Descriptions
NOTE
Process alarms, deviation alarms, and failed sensor alarms
are set individually for each loop. They are controlled by
bit settings in a number of alarm variables.
This section uses the following expressions interchange-
ably:
Users can set loop alarms to warn them of high and low
process variables and high and low deviation from the set-
point. Users can also set a loop alarm deadband value that
prevents alarm “chattering” in process and deviation
alarms. (There are also failed sensor alarms for some input
types; users cannot configure the failed sensor alarms.)
All of these alarms are individually indicated. They can
also be individually enabled, disabled, and acknowledged.
The host software can observe and set process alarm and
deviation alarm values.
NOTE
Alarms in MLS and CLS controllers depend on these five
16-bit variables, all unsigned integers: Alarm_Status,
A l a r m _ M a s k , A l a r m _ E n a b l e , A l a r m _ C o n t r o l ,
Alarm_Acknowledge.
Each of these variables is responsible for a different alarm
behavior, attribute, or condition. Each of the controller’s
alarms has 1 bit in these variables; the table below shows
the bit map for each variable. The bits are treated as 16
separate Boolean (TRUE/FALSE) variables.
Alarm_Status (13)
This parameter provides the current status of all the alarms for a loop,
except for special ramp-soak alarms. When an alarm occurs, the
controller sets the appropriate bit in Alarm_Status. When the alarm
clears, the controller clears the bit for that alarm.
Bit set to 1 True Set
Bit set to 0 False Cleared