Electronic level sensor
LR7009
9
4 Function
This unit has an IO-Link communication interface which enables direct access to process and
diagnostic data. In addition it is possible to set the parameters of the unit while it is in operation.
Operation of the unit via the IO-Link interface requires an IO-Link master.
With a PC, suitable IO-Link software and an IO-Link adapter cable, communication is possible while
the system is not in operation.
The IODDs necessary for the configuration of the unit, detailed information about process data
structure, diagnostic information, parameter addresses and the necessary information about the
required IO-Link hardware and software can be found at www.ifm.com.
4.1 Measuring principle
The device operates on the principle of guided wave radar. It measures the level using
electromagnetic pulses in the nanosecond range.
Fig. 1: Transmitting
D
Fig. 2: Receiving
The pulses are transmitted by the sensor head and guided along the rod (Fig. Transmitting). When
they hit the medium to be detected they are reflected and guided back to the sensor (Fig. Receiving).
The time between transmitting and receiving the pulse directly relates to the travelled distance (D) and
the current level. The reference for distance measurement is the lower edge of the process
connection.
The figures show operation with single probe. In case of operation with a coaxial probe, the
guided wave runs only along the inside of the coaxial pipe.
4.2 Display functions
The device displays the current level, either in cm or in percent of the final value of the measuring
range. Factory setting: cm.
The display unit is defined by programming. In the Run mode, it can be temporarily switched between
length indication (cm) and percentage:
u
Briefly press [Set].
w
The selected unit is displayed for 30 s, the corresponding LED is lit. With each push of the button
the display type is changed.
The set unit of measurement and the switching status of the outputs are indicated by LEDs.
4.3 Switching function
The device signals via two switching outputs (OUT1/OUT2) that a set limit value has been reached or
that the level is below the limit value. For each output the following switching functions can be
selected:
•
Hysteresis function / normally open (Fig. Hysteresis function): [OUx] = [Hno].
