Electronic level sensor
LW2120
9
4.1.2 Foam and turbulence
Foaming liquids or turbulence may cause weak and varying echo amplitudes. Surface turbulence is
not normally a problem unless it is excessive.
Measurement in foamy applications depends largely on the foam properties. If the foam is light and
airy, the actual level is measured. For heavy and dense foam, the unit may measure the level of the
foam’s upper surface.
4.1.3 Influence of vessel characteristics and installation
The unit should be mounted so that objects such as heating coils, ladders and agitators are not in the
radar signal path. These objects may cause false echoes which can affect the measurement and lead
to measurement errors. However, the unit has built-in functions designed to reduce the influence from
disturbing objects where such objects cannot be totally avoided. Vertical and inclined structures cause
minimal effect since the radar signal is scattered rather than directed back to the antenna.
4.2 IO-Link
IO-Link is a communication system for connecting intelligent sensors and actuators to automation
systems. IO-Link is standardised in the IEC 61131-9 standard.
General information on IO-Link at
Input Output Device Description (IODD) with all parameters, process data and detailed
descriptions of the device at
IO-Link offers the following advantages:
•
Interference-free transmission of all data and process values
•
Parameter setting in the running process or presetting outside the application
•
Parameters for identifying the connected devices in the system
•
Additional parameters and diagnostic functions
•
Automatic backup and restore of parameter sets in case of device replacement (data storage)
•
Logging of parameter sets, process values and events
•
Device description file (IODD - Input Output Device Description) for easy project planning
•
Standardised electrical connection
•
Remote maintenance
4.3 Outputs
The unit generates output signals according to the parameter setting. Two outputs are available:
•
OUT1: switching output / IO-Link
•
OUT2: analogue output 4...20 mA or switching output (configurable)
4.3.1 Analogue output
The unit provides an analogue signal proportional to the level (according to NAMUR NE43, DIN IEC
60381-1) or a switching signal on output OUT2. The analogue output can be configured.
•
Parameter [ou2] = [I] sets output OUT2 as analogue output.
•
Parameter [ASP2] sets at which measured value 4 mA are provided.
•
Parameter [AEP2] sets at which measured value 20 mA are provided.
