Watlow CLS200 - Manual (Page 84)

Chapter 3: Using the CLS200 CLS200 Series User’s Guide
68 Watlow Anafaze Doc.# 0600-3050-2000
Figure 3.9 Activation and Deactivation of
Process Alarms
Deviation Alarms
A deviation alarm occurs if the process deviates from set-
point by more than a user-specified amount. (See Figure
3.9.) Set the deviation with the DEV ALARM VALUE param-
eter in the SETUP LOOP ALARMS menu.
Upon power up or when the setpoint changes, the behavior
of the deviation alarms depends upon the alarm function:
• If the alarm type parameter is set to
ALARM, then de-
viation alarms do not activate until the after the pro-
cess variable has first come within the deviation alarm
band. This prevents nuisance alarms.
• If the alarm type parameter is set to CONTROL, then
the deviation output switches on whenever the set-
point and process variable differ by more than the de-
viation setting, regardless of whether the process vari-
able has been within the deviation band. This allows
you to use boost control upon power up and setpoint
changes.
Global Alarm
The CLS200 comes equipped with a global alarm output.
The global output is activated if one or more of the follow-
ing conditions occurs:
• A system alarm occurs, or
• A failed sensor alarm occurs and is unacknowledged,
or
Setpoint
High process alarm set point
Low process alarm setpoint
} Deadband
High process alarm on High process alarm off
Low process alarm on Low process alarm off
High deviation
alarm off
High deviation
alarm on
Low deviation
alarm off
Low deviation
alarm on
Setpoint + Deviation alarm value
Setpoint - Deviation alarm value
} Deadband
} Deadband
} Deadband