General Operation
7.3 Discrete Inputs
SITRANS LUT400
Operating Instructions, 07/2019, A5E33329501-AC
93
7.3.1.4 Effect of Backup Level Override
The level produced by a Backup Level Override condition completely replaces the level that
would otherwise be produced by normal echo processing algorithms.
This means that the Backup Level will:
● drive all readings that depend on Level (for example: space, distance, and flow)
● drive level alarms
● appear in system logs
● affect pump control
● affect totalizers (OCM and Pumped Volume)
7.3.1.5 Additional considerations
When a backup level override condition is present, a fail-safe response will never occur. This
allows pumps and other controls such as level alarms to be active even during the backup
level override condition.
7.3.2 Pump Interlocks
Discrete inputs can be used to supply pump information to the SITRANS LUT400 to set
actions that will occur when a pump is determined to be in a failed state.
For an example of how to configure a pump interlock, see Pump Control Interlocks
(Page 112).
7.3.3 Switch (DI) Alarm
An alarm can be set to activate based on the state of a discrete input. See Switch (Discrete
Input) Alarm (Page 102) for an example.
7.3.4 Discrete Input Logic
Discrete input logic affects the reaction of the discrete input. Normal state is standard
operation, with the SITRANS LUT400 sensing the material level and controlling the pumps.
The contacts of the signalling device connected to the discrete inputs may be normally open
or
normally closed.
Example:
Normal state for a backup high level switch is open, and the contacts on the discrete input
are wired as
normally open.
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