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If you select FailSafe Mode at menu 1E, menus 08 and 18 are linked
High or FailSafe Low can be selected. The factory setting for menu 1E is FailSafe High
(FSH). Menu 08 controls the mA output, and menu 18 controls the solid-state output.
In FailSafe High mode, (FSH):
•
High Signal current (20 mA) and solid-state switch closed in normal conditions
when probe is uncovered.
•
Low Signal current (3.6 mA) and solid-state switch open when fault/error
occurs.
In FailSafe Low mode, (FSL):
•
Low Signal current (4 mA) and solid-state switch open in normal conditions
when probe is uncovered.
•
High Signal current (22mA) and solid-state switch closed when fault/error
occurs.
If you do not use communications to receive status information, we recommend utilizing
analog fault signalling (menu 08) in order to be warned if a fault or failure occurs.
Via the solid-state output
The solid-state switch can be wired up to an external relay, to provide a second level of
protection. It can then be used to activate a failure alarm, or a level switch. (See page 96
for details of a typical application using the analog signal in 2-state mode to provide a
high alarm, and using the solid-state switch to provide a high-high alarm.)
Via HART
HART Response Code Information
See page 84 for
by a response code. It is then up to the Host to decide what to do in the case of a fault
situation. The Host may decide to issue Command 48, which returns more detailed
information.
Adjusting alarm settings:
The adjustable hysteresis and time delay settings allow you to adjust the unit for
applications with a lot of surface movement.
With a moving surface that fluctuates between 79% and 80%, if the hysteresis is set
so that 80 is on and 79 is off, the alarm will constantly alternate between on and off.
To prevent this, either set a time delay, or adjust the hysteresis:
•
Set the time delay to10 seconds, for example: the alarm will be on only after the
surface has been at 80% for at least 10 seconds.
•
Reset the hysteresis: for example, set the Upper Threshold setting for 80 and the
Lower Threshold setting for 70. The unit will ignore smaller surface fluctuations.
1.
FailSafe Mode at menu 1E provides a shortcut, by contrast with Free
Programming Mode where all menu items are completely independent. You can
make the same selections in FPM, but you need to set each menu item
individually.
Page 14
Pointek CLS500 – INSTRUCTION MANUAL
1
, and either FailSafe
. Each HART message is accompanied
7ML19985GG03
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