GUIDE TO INSTALLATION AND OPERATION
HCO-1822 |
11
Figure 3.9 Alarms panel
Preview Output tab
Use this tab to select the source for the preview output
•
Auto
Opposite input from that selected for the
Program output
•
Input 1
Input 1
•
Input 2
Input 2
•
Program:
the same as the Program output
3.4.3
Th
e Alarms
panel
The HCO-1822 continuously monitors the condition and
status of the input signals it is processing. The information is
used to decide whether the input must be switched in Auto
mode. It is also used to flag the status of the card in the
iControl system.
In general:
•
A number of parameter values are continuously
tested against user-defined thresholds or for
presence/absence.
•
Each parameter test is assigned a Level, to
determine the extent to which it contributes to the
changeover decision.
Many alarms can be enabled or disabled using the
Enable
checkbox in their control panel (see below).
An alarm that is enabled:
•
contributes to the switch decision process based on
its LEVEL.
•
Is reflected in the device status as reported to
iControl (LEVEL has no bearing on this)
Each alarm is assigned a LEVEL that determines its
contribution to the switch decision process. Possible levels
are:
•
1 – highest significance
•
2 – lower significance
•
OFF – not used in the switch decision process
Some alarms are arbitrarily assigned as Level 1 and cannot be
changed by the user (e.g. no signal present is always a Level 1
alarm). Their Enable checkbox is ticked, and greyed-out.
Other alarms have a pulldown in their control panel that allows the
user to set the level.
The HCO-1822 uses the most significant alarm detected for an input
as the alarm level for that input, and then uses the truth table shown
here to decide whether to switch from input 1 to input 2 and back.
INPUT 1
INPUT 2
OUTPUT:
SELECT
INPUT #
Alarm level
Alarm level
1
2
1
2
○
○
x
x
1
○
●
○
○
2
○
●
○
●
1 or last
○
●
●
x
1
●
x
○
○
2
●
x
○
●
2
●
x
●
x
1 or last
● = Alarm at this level
○ = No Alarm at this level
x = Don't care
Figure 3.8 Preview output source selection
