IFM LK81 Series User manual

Operating instructions
Electronic level sensor
LK81xx
UK
80264351 / 01 11 / 2018

2
Contents
1 Preliminary note...................................................................................................4
1.1 Symbols used ................................................................................................4
2 Safety instructions ...............................................................................................4
3 Functions and features ........................................................................................5
3.1 Application area .............................................................................................5
3.2 Restriction of the application area ................................................................5
4 Getting started .....................................................................................................6
4.1 Example configuration 1 ................................................................................6
4.2 Example configuration 2 ................................................................................7
5 Function...............................................................................................................8
5.1 Measuring principle .......................................................................................8
5.2 Operating principle / features of the unit........................................................8
5.2.1 Operating modes ..................................................................................9
5.2.2 Notes on integrated overflow prevention ..............................................9
5.2.3 Display and switching functions..........................................................10
5.2.4 Offset for indicating the real level in the tank...................................... 11
5.2.5 Defined state in case of a fault ........................................................... 11
5.2.6 IO-Link function .................................................................................. 11
6 Installation..........................................................................................................12
6.1 Installation instructions for operation with overflow prevention ..................13
6.2 Installation instructions for operation without overflow prevention ..............14
6.2.1 Installation in the inactive zone...........................................................14
6.2.2 Installation in the active zone .............................................................15
6.3 Further notes on installation / accessories ..................................................16
6.3.1 Marking of the installation height ........................................................16
7 Electrical connection..........................................................................................17
8 Operating and display elements ........................................................................19
9 Menu..................................................................................................................20
9.1 Menu structure.............................................................................................20
10 Parameter setting ............................................................................................21
10.1 Parameter setting in general .....................................................................21
10.2 Basic settings ...........................................................................................22

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10.2.1 Set unit of measurement [uni]...........................................................22
10.2.2 Set offset [OFS] ................................................................................22
10.2.3 Set medium [MEdI] ...........................................................................23
10.2.4 Set overflow prevention [OP] ..........................................................23
10.2.5 Adjust overflow prevention [cOP]......................................................24
10.3 Set output signals ......................................................................................26
10.3.1 Set output function [oux] for OUTx ...................................................26
10.3.2 Define switching limits [SPx] / [rPx] (hysteresis function) .................26
10.3.3 Define switching limits [FHx] / [FLx] (window function).....................26
10.3.4 Set switching delays [dSx] for the switching outputs ........................27
10.3.5 Set switch-off delay [drx] for switching outputs.................................27
10.3.6 Define switching logic [P-n] for the outputs ......................................27
10.3.7 Define response of the outputs in case of a fault [FOUx] .................27
10.3.8 Configure display [diS]......................................................................27
10.3.9 Reset all parameters to factory settings [rES] ..................................27
11 Notes on parameter setting via IO-Link ...........................................................28
12 Operation.........................................................................................................28
12.1 Operation indication...................................................................................28
12.2 Read set parameters .................................................................................29
12.3 Error indications.........................................................................................30
12.4 Output response in different operating states............................................30
13 Technical data..................................................................................................30
13.1 Setting values [OFS]..................................................................................31
13.2 Setting values [OP]....................................................................................31
13.3 Calculation aids [OP] .................................................................................32
13.3.1 Definition "from the cover“ ................................................................32
13.3.2 Definition "from the bottom"..............................................................32
13.4 Setting ranges [SPx] / [FHx] and [rPx] / [FLx] ...........................................33
14 Maintenance / cleaning / change of medium ..................................................34
14.1 Maintenance information for operation without overflow prevention .........34
15 Factory setting .................................................................................................35
16 Applications......................................................................................................36
16.1 Storage tank ..............................................................................................36
16.2 Pumping station.........................................................................................38

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1 Preliminary note
1.1 Symbols used
►Instructions
> Reaction, result
[…] Designation of keys, buttons or indications
→Cross-reference
Important note
Non-compliance may result in malfunction or interference.
Information
Supplementary note.
CAUTION
Warning of personal injury.Slight reversible injuries may result.
2 Safety instructions
• Read this document before setting up the product and keep it during the entire
service life.
• The product must be suitable for the corresponding applications and
environmental conditions without any restrictions.
• Only use the product for its intended purpose
(→ Functions and features).
• Only use the product for permissible media (→ Technical data).
• If the operating instructions or the technical data are not adhered to, personal
injury and/or damage to property may occur.
• The manufacturer assumes no liability or warranty for any consequences
caused by tampering with the product or incorrect use by the operator.
• Installation, electrical connection, set-up, operation and maintenance of the
product must be carried out by qualified personnel authorised by the machine
operator.
• Protect units and cables against damage.

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• The unit complies with the standard EN 61000-6-4. The unit may cause radio
interference in domestic areas. If interference occurs, the user must take
appropriate actions.
3 Functions and features
3.1 Application area
The unit was especially designed to meet the requirements of machine tool buil-
ding. It is particularly suitable for monitoring coolant emulsions (also dirty) as well
as cutting and hydraulic oils.
3.2 Restriction of the application area
• The unit is not suitable for:
- acids and alkalis
- hygienic and electroplating applications
- highly conductive and adhesive media (e.g. glue, shampoo)
- granulates, bulk material
- use in grinders (increased risk of formation of deposits).
• It is possible that foam of good conductivity is detected as level.
►Check proper function by an application test.
• For water and hydrous media with temperatures > 35 °C, install the unit in a
climatic tube (→ Accessories).
• For automatic medium detection (→ 5.2.1):
For media which are very inhomogeneous, separate from each other thus
forming separation layers (e.g. oil layer on water) the following applies:
►Check proper function by an application test.

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4 Getting started
For fast set-up, the example configurations described in the following can be used
for most applications. The indicated minimum distances apply exclusively to each
separately described case.
4.1 Example configuration 1
Unit LK8122 (probe length L= 264 mm)
Medium to be detected: Mineral oil
Operating mode: Manual media selection with overflow prevention
(factory setting) → 5.2.1
Installation environment: Metal tank, installation to Fig. 4-1
►Install unit.
►Observe the distances (x), (u) and (c):
x: min. 4.0 cm
u: min. 1.0 cm
c: max. 14.0 cm
Fig. 4-1
OP
c
►Ground sensor and tank via an electrical
connection (→ 7).
►Observe the parameter setting sequence:
- [MEdI] = [OIL.2] (→ 10.2.3)
- [OFS] = (u); e.g. (u) = 2.0 cm (→ 5.2.4)
- [OP] = Set the overflow prevention OP at a
distance (y) greater than 4.5 cm below the
mounting element.
For distances (y) smaller than 4.5 cm there
may be malfunctioning and error messages
during the adjustment process [cOP].
Step increment and setting range: (→ 13.1)
Calculation aids for [OP]: (→ 13.3).
►Adjust overflow prevention OP to [cOP] (→ 10.2.5).
>The unit is ready for operation.
►Make further settings if necessary.
►Check whether the unit operates correctly.

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4.2 Example configuration 2
Unit LK8123 (probe length L= 472 mm)
Medium to be detected: coolant emulsion
Operating mode: automatic medium detection ((→ 5.2.1))
Installation environment: metal tank, installation to Fig. 4-2
►Install unit.
►Observe the distances (x), (u) and (c):
x: min. 4.0 cm
u: min. 1.0 cm
c: max. 23.0 cm
►Ground sensor and tank via an electrical
connection (→ 7).
►Observe the maximum permitted level (b).
A distance (a2) greater than 5.0 cm has to
be observed between maximum level (b)
and mounting element.
►Observe the parameter setting sequence:
- [MEdI] = [Auto] (→ 10.2.3)
- [OFS] = (u); e.g. (u) = 1.0 cm (→ 5.2.4)
- [SP1] = Set the switch point at a distance (a2)
greater than 5.0 cm below the
mounting element.
Fig. 4-2
c
bu a2
x
Adjustable step increment: 0.5 cm.
Switch point [SP1] is used as overflow prevention
(pump off, close inlet, ...).
►Unit must be reinitialised:
►Switch the operating voltage off and on again.
>The unit is ready for operation.
►Make further settings if necessary.
►Check whether the unit operates correctly.

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5 Function
5.1 Measuring principle
The sensor determines the level according to the capacitive measuring principle:
• An electrical field [E] is generated
and influenced by the medium to be
detected. This change to the field
causes a measurement signal that
is electronically evaluated.
• The dielectric constant of a medium
is important for its detection. Media
with a high dielectric constant
(e.g. water) generate a strong
measurement signal, media with a
low dielectric constant (e.g. oils) a
correspondingly lower signal.
• The active measuring range of the
sensor probe is composed of 16
capacitive measuring segments.
They generate measurement
signals depending on the degree of
coverage.
Fig. 5-1
A II
E
I: inactive zone
A: active zone (16 active segments)
E: electrical field
Dimensions → Technical data sheet
5.2 Operating principle / features of the unit
The unit can be installed in tanks of different sizes. Observe the notes on
installation.
4 outputs are available. They can be set separately.
OUT1 switching signal for level limit / IO-Link
OUT2
OUT3
OUT4
switching signal for level limit
To adjust the unit to the application, it provides the following operating modes:

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5.2.1 Operating modes
1. Manual media selection with overflow prevention (factory setting)
Recommended! Highest operational reliability!
The medium to be detected is set manually [MEdI]. In addition, an integrated,
independently functioning overflow prevention is available.
2. Manual media selection without overflow prevention
Medium operational reliability!
The medium to be detected is set manually as described under 1. However,
the overflow prevention is deactivated. For this reason, no adjustment is
required.
3. Automatic medium detection
Lowest operational reliability!
Each time the operating voltage is switched on, the unit adjusts itself to the
medium and the installation environment.
For automatic media detection, no overflow prevention is available.
Automatic media detection can only function properly under certain
conditions (e.g. compliance with special mounting specifications,
restrictions for operation and maintenance).
5.2.2 Notes on integrated overflow prevention
With the parameter [OP] (OP = overflow prevention), one of the upper measuring
segments is defined as integrated overflow prevention OP.
• If the overflow prevention OP is activated, an adjustment to the installation
situation has to be made [cOP]. Otherwise, the unit is not ready for operation;
[ ] is displayed until readiness (→ 12.1).
• The overflow prevention OP can be deactivated ([OP] = [OFF]).
Deactivating the overflow prevention OP can impair the operational
reliability. For optimum operation and maximum operational reliability, we
therefore recommend to not deactivate the overflow prevention OP.
• The overflow prevention OP is the maximum limit of the measuring range. The
switch points [SPx] / [FHx] are always below [OP]!

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• The overflow prevention OP is not assigned to a separate output! It offers
additional protection and only switches if, as the level rises, one of the output
has not switched even though the corresponding switch point has been
exceeded (e.g. due to application-related malfunctions).
• Typically the overflow prevention OP reacts when the selected measuring
segment has been reached (a few mm before the set OP value).
• The overflow prevention OP reacts immediately and without delay. The set
delay times (e.g. of a switch point directly below) have no effect on the overflow
prevention OP.
• The response of the overflow prevention OP is indicated on the display ("Full"
and indication of the current level change every second).
5.2.3 Display and switching functions
The unit displays the current level, selectable in cm or inches. The set unit of mea-
surement and the switching status of the outputs are indicated by LEDs.
The unit signals via four switching outputs (OUT1...OUT4) that a set limit has
been exceeded or that the level is below the limit. The parameters of the switching
outputs can be set.
• Hysteresis function / normally open (Fig. 5-2): [oux] = [Hno].
• Hysteresis function / normally closed (Fig. 5-2): [oux] = [Hnc].
First the set point [SPx] is set, then the reset point [rPx] with the requested
difference.
The hysteresis for the overflow prevention OP is fixed.
• Window function / normally open (Fig. 5-3): [oux] = [Fno].
• Window function / normally closed (Fig. 5-3): [oux] = [Fnc].
The width of the window can be set by means of the difference between
[FHx] and [FLx]. [FHx] = upper value, [FLx] = lower value.

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Fig. 5-2 Fig. 5-3
SP
rP
t
L
FH
FL
1
0
1
0
FE
Fno
Fnc
L: level HY: hysteresis FE: window
5.2.4 Offset for indicating the real level in the tank
The zone between tank bottom and lower edge of the probe can be entered as
offset value [OFS]. So display and switch points refer to the actual level (point of
reference = tank bottom).
For [OFS] = [0]: The reference point is the lower edge of the measuring
probe.
The set offset only refers to the display on the unit. It has no effect on the
process value transmitted via IO-Link. The OFS parameter, however, is
correctly transmitted via IO-Link and can therefore be taken into account.
More information (→ 5.2.6).
5.2.5 Defined state in case of a fault
In case of a fault, a state can be defined for each output. If a fault is detected or if
the signal quality is below a minimum value, the outputs pass into a defined state.
For this case the response of the outputs can be set via the parameters [FOU1]...
[FOU4] (→ 10.3.7).
5.2.6 IO-Link function
This unit has an IO-Link communication interface which requires an IO-Link ca-
pable module (IO-Link master) for operation.
The IO-Link interface enables direct access to the process and diagnostic data
and provides the possibility to set the parameters of the unit during operation.

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In addition, communication is possible via a point-to-point connection with a USB
adapter cable.
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.
6 Installation
CAUTION
The housing can heat up considerably.
> risk of burns
►Cover to prevent accidental injury.
Fig. 6-1
OP
c
L:
M:
c:
probe length
zone for mounting elements
maximum outside length
u ... y:
OP:
B:
minimum distances
overflow prevention
metal object inside the tank
Table 6-1
LK8122 LK8123 LK8124
[cm] [inch] [cm] [inch] [cm] [inch]
L (rod length) 26.4 10.4 47.2 18.6 72.8 28.7
M (mounting zone) 14.0 5.5 23.0 9.1 36.0 14.2
c (max. outside length)*

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* Applies to installation as shown (wall thickness of the tank lid was neglected;
mounting element does not protrude inside the tank).
Otherwise note mounting zone M.
6.1 Installation instructions for operation with overflow
prevention
[MEdI] = [CLW..] or [OIL..]
[OP] = [value ...] (overflow prevention OP activated)
It is allowed to fix mounting elements in the mounting zone (M) (Fig. 6-1).
►Adhere to the maximum permitted outside length (c) (Table
►Observe the minimum distances according to Fig. 6-1 and Table 6-2.
►Observe the notes on the integrated overflow prevention OP.
The overflow prevention OP must:
1. be below the mounting element.
2. be set at a minimum distance (y) to it.
The minimum distance is measured between the lower edge of the
mounting element and the OP value .
Table 6-2
MEdI = CLW.1 MEdI = CLW.2, OIL.1 MEdI = OIL.2
[cm] [inch] [cm] [inch] [cm] [inch]
x 2.0 0.8 3.0 1.2 4.0 1.6
u 1.0 0.4 1.0 0.4 1.0 0.4
y (LK8122) 2.5 1.0 3.5 1.4 4.5 1.8
y (LK8123) 4.5 1.8 5.5 2.2 6.5 2.6
y (LK8124) 6.0 2.4 7.0 2.8 8.0 3.2
v 4.5 1.8 4.5 1.8 4.5 1.8
w 4.0 1.6 5.0 2.0 6.0 2.4
Calculation aids for [OP] (→ 13.3)

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6.2 Installation instructions for operation without overflow
prevention
[MEdI] = [Auto] or [OP] = [OFF] (overflow prevention OP deactivated)
6.2.1 Installation in the inactive zone
Between the maximum level (b1) and the inactive zone (I1), the minimum
distance (a1) has to be adhered to (see Fig. 6-2 and Table 6-3) !
►Fix the unit using mounting elements
in the inactive zone (I1). The outside
length (c) must not exceed (I1) (see
Table 6-3).
►Ensure that the maximum level (b1)
is not exceeded after completed
installation (see Table 6-3).
►Observe further minimum distances
according to Table 6-4.
Fig. 6-2
A I1
c
I2
b1 a1
x
u
I1 / I2: inactive zones
A: active zone
a1: minimum distance between the
inactive zone (I1) and the maximum
level (b)
b1: max. level from the lower edge of the
sensor (without offset)
c: outside length
(max. outside length Table 6-1)
Table 6-3
LK8122 LK8123 LK8124
[cm] [inch] [cm] [inch] [cm] [inch]
I1 5.3 2.1 6.0 2.4 10.4 4.1
A 19.5 7.7 39.0 15.4 58.5 23.0
a1 1.0 0.4 1.5 0.6 2.5 1
b1 20.0 7.9 39.5 15.6 59.5 23.4

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6.2.2 Installation in the active zone
The minimum distance (a2) has to be observed between the maximum
level (b2) and the mounting element (Fig. 6.3 and Table 6-4) !
►Fix mounting elements in the mounting
zone (M) (Fig. 6-1). Adhere to the
maximum permitted outside length (c)
(see Table 6-1 ).
►Ensure that the maximum level (b2)
is not exceeded after completed
installation:
(b2) = (L) - (c) - (a2) (without offset).
►Observe further minimum distances
according to Table 6-4.
Fig. 6-3
cb2
L
u a2
x
c: outside length
(max. outside length Table 6-1)
a2: minimum distance between mounting
element and maximum level (b)
b2: max. level from the lower edge of
the sensor
Table 6-4
MEdI = CLW.1 MEdI = CLW.2, OIL.1 MEdI = OIL.2 / Auto
[cm] [inch] [cm] [inch] [cm] [inch]
x 2.0 0.8 3.0 1.2 4.0 1.6
u 1.0 0.4 1.0 0.4 1.0 0.4
a2 (LK8122) 2.0 0.8 2.5 1.0 3.0 1.2
a2 (LK8123) 4.0 1.6 4.5 1.8 5.0 2.0
a2 (LK8124) 6.0 2.4 7.0 2.8 8.0 3.2
v *)4.5 1.8 4.5 1.8 4.5 1.8
w *)4.0 1.6 5.0 2.0 6.0 2.4
*)→ Fig. 6-1.

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In case of automatic medium detection [MEdI] = [Auto] or deactivated
overflow prevention [OP] = [OFF], the sensor reinitialises itself each time it
is switched on and makes adjustments to the medium and the installation
environment. The active zone / measuring range must not be completely
covered by the medium. The indicated minimum distances ensure this. Too
short a distance may lead to maladjustments and malfunctions.
6.3 Further notes on installation / accessories
• For mounting in plastic pipes / plastic tanks, the inside (pipe) diameter must at
least be 12 cm (4.8 inches). Install sensor in the centre.
• For mounting in metal pipes the inside pipe diameter (d) must be at least:
Table 6-5
MEdI = CLW.1 MEdI = CLW.2, OIL.1 MEdI = OIL.2 / Auto
[cm] [inch] [cm] [inch] [cm] [inch]
d 4.0 1.6 6.0 2.4 10.0 4.0
6.3.1 Marking of the installation height
►Fix the set installation height with the supplied
stainless steel tube clip.
If the sensor is removed from the fixture for main-
tenance reasons, the clip serves as a limit stop
when remounting the sensor. Thus an inadvertent
maladjustment of the sensor is excluded. This is
in particular necessary for the correct function of
the overflow prevention OP.
►Fit the stainless steel tube clip using pliers.
►Ensure a safe fit.
►To remove the clip it has to be destroyed.

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7 Electrical connection
The unit must be connected by a qualified electrician.
The national and international regulations for the installation of electrical
equipment must be adhered to.
Voltage supply according to EN 50178, SELV, PELV.
►Disconnect power.
►Connect the unit as follows:
Core colours
6
2
1
4
57
3
OUT 4
OUT 1
OUT 3
L+
OUT 2
L
BU
BK
WH
GY
PK
VT
BN
3
4
2
5
6
7
1
Pin Socket ifm to
DIN 47100
1 BN brown white
2 WH white brown
3 BU blue green
4 BK black yellow
5 GY grey grey
6 PK pink pink
7 VT violet blue
OUT1: switching output / IO-Link
OUT2: switching output
OUT3: switching output
OUT4: switching output
Colours to ifm
Example circuits
4 x pnp 4 x npn
L+
BU
BN
3
4 BK
7
6
1
L
PK
VT
2 WH
GY5
4: OUT1
2: OUT2
5: OUT3
6: OUT4
L+
BU
BN
3
4 BK
6
1
PK
L
2 WH
GY5
4: OUT1
2: OUT2
5: OUT3
6: OUT4
7VT

18
For reliable function, the sensor housing must be
electrically connected to the counter-electrode
(grounding).
►Use the housing connection (see drawing) and
a short piece of cable with a core cross section
of min. 1.5 mm2.
When using metal tanks, the tank wall serves as
the machine earth.
For plastic tanks, a counter-electrode must be pro-
vided, e.g. a metal plate inside the tank in parallel
with the probe. Adhere to minimum distances to the
probe.

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8 Operating and display elements
10
Mode/Enter Set
1 2 7 8 3 4 5 6
11
9
1 to 8: Indicator LEDs
LED 1 indication in centimetres
LED 2 indication in inches
LEDs 3...4 not used
LED 5 switching status OUT4 (on when output 4 is switched)
LED 6 switching status OUT3 (on when output 3 is switched)
LED 7 switching status OUT2 (on if output 2 is switched)
LED 8 switching status OUT1 (on if output 1 is switched)
9: [Mode/Enter] button
- selection of the parameters and acknowledgement of the parameter values
10: [Set] button
- setting of the parameter values (continuously by holding pressed, incrementally by
pressing once)
12: Alphanumeric display, 4 digits
- display of the current level
- display of the parameters and parameter values
- display of the operating and fault indication

20
9 Menu
9.1 Menu structure
M
M
M
M
M
M
MEdl CLW.1
OP 20.4
cOP
EF
donE
S
S
S
S
M
rES - - - -
ou1 Hno
ou2
M
SP1 FH1
S
M
M
M
S
6.0 6.0
rP1 FL1
S
M
S
M
5.5 5.5
M
SP2 FH2
S
M
M
M
S
10.0 10.0
rP2 FL2
S
M
S
M
9.5 9.5
M
SP3 FH3
S
M
M
M
S
15.0 15.0
rP3 FL3
S
M
S
M
14.5 14.5
M
SP4 FH4
S
M
M
M
S
20.0 20.0
rP4 FL4
S
M
S
M
19.5 19.5
M
dS1
dS2 0.0
Hno
Hno
ou3
ou4 Hnc
0.0
dr1 0.0
dr2 0.0
dS3 0.0
dr3 0.0
dS4 0.0
dr4 0.0
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
S
M
M
M
M
M
M
M
M
M
M
M
M
M
M
S
M
M
uni cm
S
M
S
M
diS On
M
M
M
M
S
FOU1 OFF
M
S
FOU2 OFF
M
M
M
M
M
S
FOU3 OFF
M
S
FOU4 OFF
OFS 0
S
M
P-n PnP
M
M
S
cOP
8.0
Menu items highlighted in grey,
e.g. [ cOP ], are only active when assigned parameters have been selected.