Leuze electronic MLC 500 User manual

SAFE IMPLEMENTATION AND OPERATION
Original operating instructions
EN 2019/03/11 - 50125962 We reserve the right to make technical changes
MLC 520 Host/Guest
Safety Light Curtains

© 2019
Leuze electronic GmbH & Co. KG
In der Braike 1
D-73277 Owen / Germany
Phone: [phone]
Fax: [phone]
http://www.leuze.com
[email protected]
Leuze electronic MLC 520 Host/Guest 2

Table of contents
Leuze electronic MLC 520 Host/Guest 3
Table of contents
1 About this document ............................................................................................5
1.1 Used symbols and signal words ............................................................................................. 5
1.2 Checklists................................................................................................................................ 6
2 Safety .....................................................................................................................7
2.1 Intended use and foreseeable misuse.................................................................................... 7
2.1.1 Intended use........................................................................................................................7
2.1.2 Foreseeable misuse ............................................................................................................8
2.2 Necessary competencies........................................................................................................ 8
2.3 Responsibility for safety.......................................................................................................... 9
2.4 Disclaimer ............................................................................................................................... 9
3 Device description ..............................................................................................10
3.1 Device overview of the MLC family....................................................................................... 10
3.2 Connection technology ......................................................................................................... 12
3.3 Cascading ............................................................................................................................. 12
3.4 Display elements .................................................................................................................. 14
3.4.1 Operating indicators on the MLC500 transmitter..............................................................14
3.4.2 Operating indicators on the MLC520 receiver.................................................................. 15
3.4.3 Alignment display ..............................................................................................................17
4 Functions.............................................................................................................18
4.1 Start/restart interlock RES .................................................................................................... 18
4.2 EDM contactor monitoring .................................................................................................... 18
4.3 Transmission channel changeover ....................................................................................... 19
4.4 Operating range selection..................................................................................................... 19
5 Applications ........................................................................................................20
5.1 Point of operation guarding................................................................................................... 20
5.2 Access guarding ................................................................................................................... 21
5.3 Danger zone guarding .......................................................................................................... 21
6 Mounting..............................................................................................................22
6.1 Arrangement of transmitter and receiver .............................................................................. 22
6.1.1 Calculation of safety distanceS ........................................................................................22
6.1.2 Calculation of safety distance if protective fields act orthogonally to the approach direction...23
6.1.3 Calculation of safety distanceS for parallel approach to the protective field ....................27
6.1.4 Minimum distance to reflective surfaces ...........................................................................28
6.1.5 Preventing mutual interference between adjacent devices ............................................... 30
6.2 Mounting the safety sensor................................................................................................... 31
6.2.1 Suitable mounting locations ..............................................................................................31
6.2.2 Definition of directions of movement .................................................................................32
6.2.3 Fastening via BT-NC60 sliding blocks...............................................................................32
6.2.4 Fastening via BT-2HF swivel mount..................................................................................32
6.2.5 Fastening via BT-2SB10 swiveling mounting brackets .....................................................33
6.2.6 One-sided mounting on the machine table........................................................................34
6.3 Mounting accessories ........................................................................................................... 35
6.3.1 MLC-PS protective screen ................................................................................................35

Table of contents
Leuze electronic MLC 520 Host/Guest 4
7 Electrical connection..........................................................................................36
7.1 Pin assignment transmitter and receiver .............................................................................. 36
7.1.1 MLC500 transmitter..........................................................................................................36
7.1.2 MLC520 receiver ..............................................................................................................38
7.2 Circuit diagram examples ..................................................................................................... 39
7.2.1 MLC520 circuit diagram example.....................................................................................39
8 Starting up the device ........................................................................................40
8.1 Switching on ......................................................................................................................... 40
8.2 Aligning the sensor ............................................................................................................... 40
8.3 Aligning of deflecting mirrors with the laser alignment aid.................................................... 41
8.4 Unlocking start/restart interlock ............................................................................................ 42
9 Testing .................................................................................................................43
9.1 Before commissioning and following modifications .............................................................. 43
9.1.1 Checklist for integrator – to be performed prior to commissioning and following modifica-
tions...................................................................................................................................43
9.2 To be performed periodically by competent persons............................................................ 45
9.3 Periodically by the operator .................................................................................................. 45
9.3.1 Checklist – periodically by the operator.............................................................................45
10 Maintenance ........................................................................................................47
11 Troubleshooting..................................................................................................48
11.1 What to do in case of failure? ............................................................................................... 48
11.2 Operating indicators of the LEDs.......................................................................................... 48
11.3 Error messages 7-segment display ...................................................................................... 50
12 Disposing.............................................................................................................52
13 Service and support ...........................................................................................53
14 Technical data .....................................................................................................54
14.1 General specifications .......................................................................................................... 54
14.2 Dimensions, weight, response time ...................................................................................... 56
14.3 Dimensioned drawings: Accessories .................................................................................... 60
15 Order guide and accessories.............................................................................62
16 EU/EC Declaration of Conformity......................................................................69

About this document
Leuze electronic MLC 520 Host/Guest 5
1 About this document
1.1 Used symbols and signal words
Tab.1.1: Warning symbols and signal words
Symbol indicating dangers to persons
Symbol indicating possible property damage
NOTE Signal word for property damage
Indicates dangers that may result in property damage if the measures for dan-
ger avoidance are not followed.
CAUTION Signal word for minor injuries
Indicates dangers that may result in minor injury if the measures for danger
avoidance are not followed.
WARNING Signal word for serious injury
Indicates dangers that may result in severe or fatal injury if the measures for
danger avoidance are not followed.
DANGER Signal word for life-threatening danger
Indicates dangers with which serious or fatal injury is imminent if the measures
for danger avoidance are not followed.
Tab.1.2: Other symbols
Symbol for tips
Text passages with this symbol provide you with further information.
Symbol for action steps
Text passages with this symbol instruct you to perform actions.
Symbol for action results
Text passages with this symbol describe the result of the preceding action.
Tab.1.3: Terms and abbreviations
Response time The response time of the protective device is the maximum time between the
occurrence of the event that results in activation of the safety sensor and the
provision of the switching signal at the interface of the protective device (e.g.,
OFF state of the OSSD pair).
AOPD Active Optoelectronic Protective Device
(Active Optoelectronic Protective Device)
ESPE Electro-sensitive protective equipment
EDM Contactor monitoring
(External Device Monitoring)
LED LED, display element in transmitter and receiver
MLC Brief description of the safety sensor, consisting of transmitter and receiver
MTTFdMean time to dangerous failure
(Mean Time To dangerous Failure)
OSSD Safety-related switching output
(Output Signal Switching Device)

About this document
Leuze electronic MLC 520 Host/Guest 6
PFHdProbability of a dangerous failure per hour
(Probability of dangerous Failure per Hour)
PL Performance Level
RES Start/restart interlock
(Start/REStart interlock)
Scan Consecutive scans of the protective field from the first to the last beam
Safety sensor System consisting of transmitter and receiver
SIL Safety Integrity Level
State ON: device intact, OSSD switched on
OFF: device intact, OSSD switched off
Locking: device, connection or control / operation faulty, OSSD switched off
(lock-out)
1.2 Checklists
The checklists (see chapter 9 "Testing") serve as a reference for the machine manufacturer or supplier.
They replace neither testing of the complete machine or system prior to initial commissioning nor their peri-
odic testing by a qualified person (see chapter 2.2 "Necessary competencies"). The checklists contain mini-
mum testing requirements. Depending on the application, other tests may be necessary.

Safety
Leuze electronic MLC 520 Host/Guest 7
2 Safety
For mounting, operating and testing, this document as well as all applicable national and international stan-
dards, regulations, rules and directives must be observed. Relevant and supplied documents must be ob-
served, printed out and handed to affected persons.
ÄBefore working with the safety sensor, completely read and observe the documents applicable to your
task.
In particular, the following national and international legal regulations apply for the commissioning, techni-
cal inspections and work with safety sensors:
• Directive 2006/42/EC
• Directive 2014/35/EU
• Directive 2014/30/EU
• Directive 89/655/EEC supplemented by directive 95/63EC
• OSHA 1910 Subpart O
• Safety regulations
• Accident-prevention regulations and safety rules
• Ordinance on Industrial Safety and Health and employment protection act
• Product Safety Law (ProdSG and 9. ProdSV)
NOTICE
For safety-related information you may also contact local authorities (e.g., industrial inspec-
torate, employer's liability insurance association, labor inspectorate, occupational safety and
health authority).
2.1 Intended use and foreseeable misuse
WARNING
A running machine may result in serious injury!
ÄMake certain that the safety sensor is correctly connected and that the protective function of
the protective device is ensured.
ÄMake certain that, during all conversions, maintenance work and inspections, the system is
securely shut down and protected against being restarted.
2.1.1 Intended use
• The safety sensor may only be used after it has been selected in accordance with the respectively ap-
plicable instructions and relevant standards, rules and regulations regarding labor protection and safety
at work, and after it has been installed on the machine, connected, commissioned, and checked by a
competent person (see chapter 2.2 "Necessary competencies"). The devices are designed for indoor
use only.
• When selecting the safety sensor it must be ensured that its safety-related capability meets or exceeds
the required performance level PLr ascertained in the risk assessment (see chapter 14.1 "General
specifications").
• The safety sensor protects persons or body parts at points of operation, danger zones or access points
of machines and systems.
• With the access guarding function, the safety sensor detects persons only when they enter the danger
zone but cannot tell whether there are any persons inside the danger zone. For this reason, a start/
restart interlock or a suitable stepping behind protection in the safety chain is essential in this case.
• Maximum permissible approach speeds (see ISO13855):
• 1.6m/s for access guarding
• 2.0m/s for guards of points of operation
• The construction of the safety sensor must not be altered. When manipulating the safety sensor, the
protective function is no longer guaranteed. Manipulating the safety sensor also voids all warranty
claims against the manufacturer of the safety sensor.

Safety
Leuze electronic MLC 520 Host/Guest 8
• The improper repair of the protective device may result in loss of the protective function. Make no re-
pairs to the device components.
• The safety sensor must be inspected regularly by a competent person to ensure proper integration and
mounting (see chapter 2.2 "Necessary competencies").
• The safety sensor must be exchanged after a maximum of 20 years. Repairs or the exchange of wear
parts do not extend the mission time.
2.1.2 Foreseeable misuse
Any use other than that defined under the “Approved purpose” or which goes beyond that use is consid-
ered improper use.
In principle, the safety sensor is not suitable as a protective device for use in the following cases:
• Danger posed by ejected objects or the spraying of hot or hazardous liquids from within the danger
zone
• Applications in explosive or easily flammable atmospheres
2.2 Necessary competencies
The safety sensor may only be configured, installed, connected, commissioned, serviced and tested in its
respective application by persons who are suitably qualified for the given task. General prerequisites for
suitably qualified persons:
• They have a suitable technical education.
• They are familiar with the relevant parts of the operating instructions for the safety sensor and the oper-
ating instructions for the machine.
Task-specific minimum requirements for competent persons:
Configuration
Specialist knowledge and experience in the selection and use of protective devices on machines as well as
the application of technical rules and the locally valid regulations on labor protection, safety at work and
safety technology.
Specialist knowledge in programming safety-related controls SRASW acc. to ISO13849-1.
Mounting
Specialist knowledge and experience needed for the safe and correct installation and alignment of the
safety sensor with regard to the respective machine.
Electrical installation
Specialist knowledge and experience needed for the safe and correct electrical connection as well as safe
integration of the safety sensor in the safety-related control system.
Operation and maintenance
Specialist knowledge and experience needed for the regular inspection and cleaning of the safety sensor –
following instruction by the person responsible.
Servicing
Specialist knowledge and experience in the mounting, electrical installation and the operation and mainte-
nance of the safety sensor in accordance with the requirements listed above.
Commissioning and testing
• Experience and specialist knowledge in the rules and regulations of labor protection, safety at work and
safety technology that are necessary for being able to assess the safety of the machine and the use of
the safety sensor, including experience with and knowledge of the measuring equipment necessary for
performing this work.
• In addition, a task related to the subject matter is performed in a timely manner and knowledge is kept
up to date through continuous further training ‑ Competent person in terms of the German Betrieb-
ssicherheitsverordnung (Ordinance on Industrial Safety and Health) or other national legal regulations.

Safety
Leuze electronic MLC 520 Host/Guest 9
2.3 Responsibility for safety
Manufacturer and operator must ensure that the machine and implemented safety sensor function properly
and that all affected persons are adequately informed and trained.
The type and content of all imparted information must not lead to unsafe actions by users.
The manufacturer of the machine is responsible for:
• Safe machine construction and information on any residual risks
• Safe implementation of the safety sensor, verified by the initial test performed by a competent person
(see chapter 2.2 "Necessary competencies")
• Imparting all relevant information to the operating company
• Adhering to all regulations and directives for the safe commissioning of the machine
The operator of the machine is responsible for:
• Instructing the operator
• Maintaining the safe operation of the machine
• Adhering to all regulations and directives for labor protection and safety at work
• Periodic testing by a competent person (see chapter 2.2 "Necessary competencies")
2.4 Disclaimer
The liability of Leuze electronic GmbH + Co. KG is to be excluded in the following cases:
• Safety sensor is not used as intended.
• Safety notices are not adhered to.
• Reasonably foreseeable misuse is not taken into account.
• Mounting and electrical connection are not properly performed.
• Proper function is not tested (see chapter 9 "Testing").
• Changes (e.g., constructional) are made to the safety sensor.

Device description
Leuze electronic MLC 520 Host/Guest 10
3 Device description
The safety sensors from the MLC 500 series are active opto-electronic protective devices. They satisfy the
following standards:
MLC 500
Type in accordance with ENIEC61496 4
Category in accordance with ENISO13849 4
Performance Level (PL) in accordance with ENISO13849-1:2015 e
Safety Integrity Level (SIL) in accordance with IEC61508 and SILCL in ac-
cordance with ENIEC62061
3
The safety sensor consists of a transmitter and a receiver (see chapter 3.1 "Device overview of the MLC
family"). It is protected against overvoltage and overcurrent acc. to IEC60204-1 (protection class3). The
safety sensor is not dangerously influenced by ambient light (e.g., welding sparks, warning lights).
3.1 Device overview of the MLC family
The series is characterized by four different receiver classes (Basic, Standard, Extended, SPG) with spe-
cific features and properties (see table below).
Tab.3.1: Device models in the series with specific features and functions
Device type Transmitter Receiver
Function
package
Basic Standard Ex-
tended
SPG
Model MLC 500
MLC 501
MLC 500/
A
MLC 502 MLC 510
MLC 511
MLC 510/
A
MLC 520 MLC 530 MLC 530
SPG
OSSDs (2x) ■ ■ ■ ■
AS-i ■ ■
Transmission
channel
changeover
■ ■ ■ ■ ■ ■
LED indicator ■ ■ ■ ■ ■ ■ ■ ■
7‑segment
display
■■■
Automatic
start/restart
■ ■ ■
RES ■ ■ ■
EDM ■
Linkage ■
Blanking ■ ■
Muting ■
SPG ■
Multi-scan ■ ■
Range reduc-
tion
■ ■
Test input ■

Device description
Leuze electronic MLC 520 Host/Guest 11
Protective field properties
The beam distance and the number of beams are dependent on the resolution and protective field height.
NOTICE
Depending on the resolution, the effective protective field height can be larger than the optically
active area of the safety sensor housed in yellow (see chapter 3.1 "Device overview of the MLC
family" and see chapter 14.1 "General specifications").
Device synchronization
The synchronization of receiver and transmitter for creating a functioning protective field is done optically,
i.e. without cables, via two specially coded synchronization beams. A cycle (i.e. a pass from the first to the
last beam) is called a scan. The length of a scan determines the length of the response time and affects the
calculation of the safety distance (see chapter 6.1.1 "Calculation of safety distanceS").
NOTICE
For the correct synchronization and function of the safety sensor, at least one of the two syn-
chronization beams must be free during synchronization and operation.
a
b
b
a Optically active area, housed in yellow
b Synchronization beams
Fig.3.1: Transmitter-receiver system

Device description
Leuze electronic MLC 520 Host/Guest 12
QR code
A QR code as well as the corresponding web address are located on the safety sensor.
At the web address, you will find device information and error messages (see chapter 11.3 "Error mes-
sages 7-segment display") after scanning the QR code with a mobile end device or after entering the web
address.
When using mobile end devices, mobile service charges can accrue.
Fig.3.2: QR code with corresponding web address (URL) on the safety sensor
3.2 Connection technology
The transmitter and receiver feature an M12 connector as an interface to the machine control with the fol-
lowing number of pins:
Device model Device type Device plug
MLC 500 Transmitter 5-pin
MLC 520 Standard receiver 8-pin
Host devices are also equipped with an interconnection cable, 400mm long, with M12 connector for con-
necting MiddleGuest or Guest devices.
MiddleGuest devices are equipped with two interconnection cables, 400mm long, with M12 connector for
connecting Host or Guest devices.
Guest devices are equipped with an interconnection cable, 400mm long, with M12 connector for connect-
ing Host or MiddleGuest devices.
3.3 Cascading
To implement linked protective fields, up to three MLC safety light curtains can be cascaded one after the
other.
Adjacent protective fields, e.g., for stepping behind protection, can thereby be implemented without any ad-
ditional expense for control and connection. The host system performs all necessary processor tasks, pro-
vides indicators and the receiver-side interfaces to the machine and command devices.
Devices with different resolutions can be combined.
With mounting brackets (see chapter 15 "Order guide and accessories"), an L or U-shaped fixed connec-
tion can be created.

Device description
Leuze electronic MLC 520 Host/Guest 13
1
2
3
4
1 Host transmitter
2 Guest transmitter
3 Host receiver
4 Guest receiver
Fig.3.3: Cascaded system with 2 MLC safety light curtains
1
4
3
5
62
1 Host transmitter
2 MiddleGuest transmitter
3 Guest transmitter
4 Host receiver
5 MiddleGuest receiver
6 Guest receiver
Fig.3.4: Cascaded system with 3 MLC safety light curtains

Device description
Leuze electronic MLC 520 Host/Guest 14
NOTICE
With permanently connected devices the resolution at the intersection point can be greater than
the resolution of the individual devices.
The operating range of the total system is defined by the component with the shortest operating
range.
To operate a Host device without connected Guest devices, a terminating plug is required (see
chapter 15 "Order guide and accessories").
NOTICE
The total number of beams for a Host–Guest or Host–MiddleGuest guest system must
not exceed the value 400!
ÄThe number of beams for a Host–Guest or Host–MiddleGuest guest system is determined
by adding the number of beams of the individual devices (see chapter 14.2 "Dimensions,
weight, response time").
3.4 Display elements
The display elements of the safety sensors simplify start-up and fault analysis.
3.4.1 Operating indicators on the MLC500 transmitter
Located in the connection cap on the transmitter are two LEDs which serve as function indicators:
1
2
1 LED1, green/red
2 LED2, green
Fig.3.5: Indicators on the MLC 500 transmitter
Tab.3.2: Meaning of the LEDs on the transmitter
LED Color State Description
1 Green/red OFF Device switched off
Red Device error
Green Normal operation
2 Green Flashing For 10s after switch-on: reduced
range selected by the wiring (see
chapter 7.1 "Pin assignment trans-
mitter and receiver").
OFF Transmission channel C1
ON Transmission channel C2

Device description
Leuze electronic MLC 520 Host/Guest 15
3.4.2 Operating indicators on the MLC520 receiver
Two LEDs and a 7-segment display for showing the operating state are located on the receiver:
13
4
2
5
1 LED1, red/green
2 LED2, yellow
3 OSSD icon
4 RES icon
5 7‑segment display
Fig.3.6: Indicators on the MLC 520 receiver
Tab.3.3: Meaning of the LEDs on the receiver
LED Color State Description
1 Red/green OFF Device switched off
Red OSSD off
Red, flashing slowly (approx.1Hz) External error
Red, flashing fast (approx.10Hz) Internal error
Green, flashing slowly (ap-
prox.1Hz)
OSSD on, weak signal
Green OSSD on
2 Yellow OFF • RES deactivated
• or RES activated and enabled
• or RES blocked and protective
field interrupted
ON RES activated and blocked but
ready to be unlocked - protective
field free
7-segment display at the MLC 520 receiver
In normal operation, the 7-segment display shows the number of the selected transmission channel. In ad-
dition, it helps during the detailed error diagnostics (see chapter 11 "Troubleshooting") and serves as an
alignment aid (see chapter 8.2 "Aligning the sensor").

Device description
Leuze electronic MLC 520 Host/Guest 16
Tab.3.4: Meaning of the 7-segment display
Display Description
After switching on
8 Self test
tnn Response time (t) of the receiver in milliseconds (nn)
In normal operation
C1 Transmission channel C1
C2 Transmission channel C2
For alignment
Alignment display (see chapter 3.4.3 "Alignment display").
For error diagnostics
F… Failure, internal device error
E… Error, external error
U… Usage info, application error
Tab.3.5: Meaning of the 7-segment display
Display Description
After switching on
8 Self test
tnn Response time (t) of the receiver in milliseconds (nn)
In normal operation
C1 Transmission channel C1
C2 Transmission channel C2
For alignment
Alignment display (Alignment display).
For error diagnostics
F… Failure, internal device error
E… Error, external error
U… Usage info, application error
For error diagnostics, the error's respective letter is displayed first followed by the number code. The dis-
play is repeated cyclically. An AutoReset is carried out after 10s for errors that do not cause locking, with
an unauthorized restart being impossible. In the case of blocking errors, the voltage supply must be sepa-
rated and the cause of the error must be eliminated. Before switching on again, the steps taken before ini-
tial commissioning must be repeated (see chapter 9.1 "Before commissioning and following modifications").
The 7-segment display switches to alignment mode when the device has not yet been aligned or when the
protective field has been interrupted (after 5s). In this case, a fixed beam area from the protective field is
assigned to every segment.

Device description
Leuze electronic MLC 520 Host/Guest 17
3.4.3 Alignment display
Approximately 5s after a protective-field interruption, the 7-segment display switches to alignment mode.
In this mode, one third of the total protective field (Host, MiddleGuest, Guest) is assigned to one of the
three horizontal segments and the state of this sub-protective field displayed as follows:
Tab.3.6: Function of alignment display
Segment Description
On All beams in the beam area are uninterrupted.
Flashing At least one, but not all beams in the beam area are uninterrupted.
Switched off All beams in the beam area are interrupted.
When the protective field has been free for about 5s, the device switches back to the display of the operat-
ing mode.

Functions
Leuze electronic MLC 520 Host/Guest 18
4 Functions
An overview of features and functions of the safety sensor can be found in chapter “Device descrip-
tion” (see chapter 3.1 "Device overview of the MLC family").
Overview of functions
• Start/restart interlock (RES)
• EDM
• Range reduction
• Transmission channel changeover
4.1 Start/restart interlock RES
After accessing the protective field, the start/restart interlock ensures that the safety sensor remains in the
OFF state after the protective field has been cleared. It prevents automatic release of the safety circuits
and automatic start-up of the system, e.g. if the protective field is again clear or if an interruption in the volt-
age supply is restored.
NOTICE
For access guarding, the start/restart interlock function is mandatory. The protective device may
only be operated without start/restart interlock in certain exceptional cases and under certain
conditions acc. to ISO12100.
WARNING
Deactivation of the start/restart interlock may result in serious injury!
ÄImplement the start/restart interlock on the machine or in a downstream safety circuit.
Using start/restart interlock
ÄWire the MLC 520 receiver appropriately for the desired operating mode (see chapter 7 "Electrical con-
nection").
The start/restart interlock function is automatically activated.
Switching the safety sensor back on after shutting down (OFF state):
ÄPress the reset button (press/release between 0.15s and 4s)
NOTICE
The reset button must be located outside the danger zone in a safe place and give the operator
a good view of the danger zone so that he/she can check whether anyone is located in it (ac-
cording to IEC62046) before pressing the reset button.
DANGER
Risk of death if start/restart is operated unintentionally!
ÄEnsure that the reset button for unlocking the start/restart interlock cannot be reached from
the danger zone.
ÄBefore unlocking the start/restart interlock, make certain that no people are in the danger
zone.
After the reset button has been actuated, the safety sensor switches to the ON state.
4.2 EDM contactor monitoring
NOTICE
The contactor monitoring of the MLC 520 safety sensors can be activated through appropriate
wiring (see chapter 7.1.1 "MLC500 transmitter")!

Functions
Leuze electronic MLC 520 Host/Guest 19
The “contactor monitoring” function monitors the contactors, relays or valves connected downstream of the
safety sensor. Prerequisite for this are switching elements with positive-guided feedback contacts (normally
closed contacts).
Implement the contactor monitoring function:
• through appropriate wiring of the MLC 520 safety sensors (see chapter 7.1.1 "MLC500 transmitter").
• through the external contactor monitoring of the downstream safety relay, (e.g. MSI series from Leuze
electronic)
• or through contactor monitoring of the downstream safety PLC (optional, integrated via a safety bus)
If contactor monitoring is activated (see chapter 7 "Electrical connection"), it operates dynamically, i.e., in
addition to monitoring the closed feedback circuit every time before the OSSDs are switched on, it also
checks whether the release of the feedback circuit opened within 500 ms and, after the OSSDs are
switched off, whether it has closed again within 500 ms. If this is not the case, the OSSDs return to the
OFF state after being switched on briefly. An error message appears on the 7-segment display (E30, E31)
and the receiver switches to the fault interlock state from which it can only be returned to normal operation
by switching the supply voltage off and back on again.
4.3 Transmission channel changeover
Transmission channels are used to prevent mutual interference of safety sensors which are located close
to each other.
NOTICE
To guarantee reliable operation, the infrared beams are modulated so they can be discerned
from the ambient light. Welding sparks or warning lights, e.g. from passing high-lift trucks,
thereby do not influence the protective field.
With the factory setting, the safety sensor works in all operating modes with transmission channelC1.
The transmission channel of the receiver can be switched by changing the supply voltage polarity
(MLC520 receiver).
NOTICE
Faulty function due to incorrect transmission channel!
Select the same transmission channel on the transmitter and corresponding receiver.
4.4 Operating range selection
In addition to selecting the suitable transmission channels (see chapter 4.3 "Transmission channel
changeover"), the operating range selection also serves to prevent mutual interference of adjacent safety
sensors. At reduced operating range the light power of the transmitter reduces, so that around half of the
nominal range is reached.
Select operating range:
ÄWire pin4 (see chapter 7.1 "Pin assignment transmitter and receiver").
ðThe wiring of pin4 determines the transmitting power and thereby the range.
WARNING
Impairment of the protective function due to incorrect transmitting power!
The light power emitted from the transmitter is reduced through a single channel and without
safety-relevant monitoring.
ÄDo not use this configuration option for safety purposes.
ÄNote that the distance to reflective surfaces must always be selected so that no reflection
bypass can occur even at maximum transmitting power (see chapter 6.1.4 "Minimum dis-
tance to reflective surfaces").

Applications
Leuze electronic MLC 520 Host/Guest 20
5 Applications
The safety sensor only creates square protective fields.
5.1 Point of operation guarding
Point of operation guarding for hand and finger protection is typically the most common application for this
safety sensor. In accordance with ENISO13855, resolutions from 14to40mm make sense here. This
yields the necessary safety distance, among others (see chapter 6.1.1 "Calculation of safety distanceS").
Fig.5.1: Point of operation guarding protects reaching into the danger zone, e.g. for cartoners or filling systems
Fig.5.2: Point of operation guarding protects reaching into the danger zone, e.g. for a pick&place robot applica-
tion