Watlow CPC400 - Manual (Page 79)

CPC400 Series User’s Guide Chapter 3: Operation and Setup
Doc. 0600-2900-2000 Watlow Anafaze 65
RTD Open or RTD Shorted Alarm
The RTD open alarm occurs if the controller detects that
the positive or negative RTD lead is broken or disconnect-
ed.
The RTD shorted alarm occurs if the controller detects that
the positive and negative RTD leads are shorted.
You do not have to set any parameters for the RTD alarms.
Restore Automatic Control After a Sensor Failure
This feature returns a loop to automatic control after a
failed sensor is repaired. To enable this feature:
• Choose a digital input for the RestoreAuto parameter
in the Control menu.
• Connect the digital input to the dc common terminal
on the controller.
Process Alarms
The CPC400 has four process alarms, each of which you
can configure separately for each loop:
• Alarm low
• Alarm high
• Low deviation alarm
• High deviation alarm
What Happens if a Process Alarm Occurs?
If a process alarm occurs, the controller does the following:
• Shows an alarm code on the display. See Alarm Dis-
plays on page 51.
• Activates the global alarm output. See Global Alarm
on page 67.
• Activates the digital output that is assigned to the pro-
cess alarm (if applicable). The digital output remains
active until the process variable returns within the
corresponding limit and hysteresis. The alarm output
deactivates when the process returns to normal.
Process Alarm Outputs
Any digital output that is not used as a control output can
be assigned to one or more process alarms.
The controller activates the output if any alarm assigned to
the output is active. Process alarm outputs are non-latch-
ing—that is, the output is deactivated when the process re-
turns to normal, whether or not the alarm has been
acknowledged.
Specify the active state of process alarm outputs at the
D/O alarm polarity setting in the Global setup menu.