IFM DU110S User manual

80227414 / 00 08 / 2020
Original Installation Instructions
Safety Underspeed Monitor
DU110S UKUK

2
Contents
1 Preliminary note���������������������������������������������������������������������������������������������������4
1�1 Symbols used ������������������������������������������������������������������������������������������������4
1�2 Warnings used�����������������������������������������������������������������������������������������������5
2 Safety instructions �����������������������������������������������������������������������������������������������5
2�1 General requirements on the safety-related functions�����������������������������������6
3 Functions and features ����������������������������������������������������������������������������������������7
3�1 General function description��������������������������������������������������������������������������7
3�2 Safe state of the output relays (failsafe state) �����������������������������������������������7
3�3 Switching function "underspeed" �������������������������������������������������������������������8
3�4 Hysteresis������������������������������������������������������������������������������������������������������8
3�5 Initialisation����������������������������������������������������������������������������������������������������8
3�6 Start-up delay ������������������������������������������������������������������������������������������������9
3�7 Fault output (Y7)������������������������������������������������������������������������������������������10
3�8 Underspeed output (Y8) ������������������������������������������������������������������������������10
3�9 Feedback circuit for external device monitoring (Y1-Y2)�����������������������������10
4 Installation���������������������������������������������������������������������������������������������������������� 11
4�1 Mechanical installation of the device ����������������������������������������������������������� 11
4�2 Remove the device�������������������������������������������������������������������������������������� 11
5 Electrical connection������������������������������������������������������������������������������������������12
5�1 Terminals �����������������������������������������������������������������������������������������������������12
5�2 Automatic/manual mode selection���������������������������������������������������������������14
5�2�1 Automatic operation����������������������������������������������������������������������������14
5�2�2 Manual operation��������������������������������������������������������������������������������16
5�3 Enable inputs�����������������������������������������������������������������������������������������������18
6 Indicators and operating elements���������������������������������������������������������������������19
6�1 LEDs������������������������������������������������������������������������������������������������������������19
6�2 Switches ������������������������������������������������������������������������������������������������������20
7 Set-up ����������������������������������������������������������������������������������������������������������������21
7�1 Configuration position (factory setting) ��������������������������������������������������������21
7�2 Setting the switch point��������������������������������������������������������������������������������22
7�3 Examples of switch point settings����������������������������������������������������������������23
7�4 Checklist after installation and set-up����������������������������������������������������������23
7�5 Notes on the positioning of the sensors / damping elements ����������������������24

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8 Technical data����������������������������������������������������������������������������������������������������26
9 Maintenance, repair and disposal����������������������������������������������������������������������28
10 Approvals/standards ����������������������������������������������������������������������������������������28
11 Terms and abbreviations����������������������������������������������������������������������������������29
This document is the original instructions�

4
1 Preliminary note
The instructions are part of the unit� They are intended for authorised persons
according to the EMC and Machinery Directive and safety regulations� The
instructions contain information about the correct handling of the product� Read
the instructions before use to familiarise yourself with operating conditions,
installation and operation�Adhere to the safety instructions�
Instructions, technical data, approvals, accessories and further information at
www�ifm�com�
1.1 Symbols used
►Instruction
> Reaction, result
[…] Designation of keys, buttons or indications
→Cross-reference
Important note
Non-compliance may result in malfunction or interference�
Information
Supplementary note�
LED on
LED off
LED flashes

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1.2 Warnings used
WARNING!
Warning of serious personal injury�
Death or serious irreversible injuries may result�
CAUTION!
Warning of personal injury�
Slight reversible injuries may result�
ATTENTION!
Warning of damage to property�
2 Safety instructions
• Follow the operating instructions�
• Improper use may result in malfunctions of the unit� This can lead to personal
injury and/or damage to property during operation of the machine� For this
reason note all remarks on installation and handling given in this document�
Also adhere to the safety instructions for the operation of the whole installation�
• In case of non-observance of notes or standards, especially when tampering
with and/or modifying the unit, any liability and warranty is excluded�
• The unit must be installed, connected and put into operation by a qualified
electrician trained in safety technology�
• The applicable technical standards for the corresponding application must be
complied with�
• For installation the requirements according to EN 60204 must be observed�
• Connect and lay all cables according to EN ISO 13849-2 D�5�2 (Safety of
machinery - Safety-related parts of control systems)�
• In case of malfunction of the unit please contact the manufacturer� Tampering
with the unit is not allowed�
• Disconnect the unit externally before handling it� Also disconnect any
independently supplied relay load circuits�
• After setup the system has to be subjected to a complete function check�

6
• Use the unit only in specified environmental conditions (→ 8 Technical data)�
In case of special operating conditions please contact the manufacturer�
• Use only as described below (→ 3 Functions and features)�
2.1 General requirements on the safety-related functions
The device complies with the functional and organisational requirements of
EN ISO 13849-1 Performance-Level "e" and EN 62061 SIL "3"�
To maintain Safety Integrity Level (SIL) "3" requirements the two input
sensors should not be of the exact same type and independent of each
other�
Common cause failures between input sensors must be excluded by
observing an appropriate cable installation (i�e� separate cable paths)� Input
sensors must be mounted separately from each other�
To maintain the category 4 requirements during longer periods of standstill
the machine operator has to ensure that the machine to be monitored is
operated once a day (t < 24 h)�

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3 Functions and features
3.1 General function description
The device is a two-channel pulse evaluation system for safe underspeed
detection�
To do so, it receives the pulse sequences from the pulse pick-ups connected to
the inputs� The device calculates the resulting frequency�
By continuously comparing the input frequency (actual value) and the switch point
(target value) the device promptly detects underspeed of the set switch point�
The NO contacts of the internal relays are connected in series so that the current
paths are not closed before both relays have switched�
By means of the current paths a door guard locking system can, for example, be
controlled�
Block diagram
3.2 Safe state of the output relays (failsafe state)
Output relays are de-energised� Current paths are open�

8
3.3 Switching function "underspeed"
The output relays de-energise when underspeed occurs (frequency FuH has been
reached)� The relays energise again when the input frequency exceeds the set
switch point Fu�
Fuh
Fu
Safety
output
f in
t
ONONOFF OFF OFF
Switching characteristics of the current paths (safety-related outputs)
Fu:
Fuh:
Frequency underspeed (= set switch point)
Frequency underspeed – hysteresis
3.4 Hysteresis
The hysteresis determines the distance between the switch point (current paths
close) and the switch-off point (current paths open)�
The hysteresis value is fixed at 5 %�
If the input frequency decreases by 5% below the set switch point Fu, the output
relays de-energise and the current paths are open�
Example switch point Fu = 10 Hz:
• Current paths close if Fu is exceeded (rising frequency)
• Current paths open if Fuh is not reached (here 9�5 Hz, falling frequency)�
3.5 Initialisation
Directly after power on, the device carries out a complete self-test� This
initialisation phase takes approx� 3 s�

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3.6 Start-up delay
To suppress unintended switch-off of the current paths during the start-up of the
machine the device has a fixed start-up delay of 10 seconds�
VORSICHT!
Personal injury may result�
During these 10 seconds the protective function is temporarily
suspended�
Carefully check your risk analysis in order to assess whether this
function is compatible with your application and what additional
measures have to be taken (i�e� guard lock, protective fence, etc�)�
Startup
delay
time
Safety
output
Fu
Fuh
f in
t
t
ON ON ON
10 s 10 s
Current paths (safety-related outputs) in dependence of the start-up delay
When the operating voltage has been switched on, the current paths are switched
off for max� 10 seconds because of the underspeed�
If after this period the input frequency Fu has not been reached, the current paths
are switched off�
The start-up delay includes the initialisation phase (→ 3.5 Initialisation)�

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3.7 Fault output (Y7)
The transistor output "Fault" (Y7) opens when an internal or external error occurs�
The error message is reset by interrupting the voltage supply�
3.8 Underspeed output (Y8)
The underspeed output (Y8) is "HIGH" when the current paths are closed and
"LOW" when the current paths are opened�
3.9 Feedback circuit for external device monitoring (Y1-Y2)
If underspeed is detected, the current paths open and the external relays are de-
energised�
If the feedback circuit does not close within 1 s, an error message is provided�
LED [FAULT] flashes 3 times�
Also see (→ 6.1 LEDs)�
If the feedback function is not required, the terminals Y1-Y2 must be
permanently bridged�
Feedback contacts (NC contacts of the
external relays in series)
Without feedback function with bridge

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4 Installation
4.1 Mechanical installation of the device
►Mount the device on a 35 mm DIN rail in a housing protected against dust and
humidity (min� IP 54)�
Leave enough space between the device and the top and bottom of the
housing to enable air circulation and to avoid excessive heating�
Take into account the internal heating of all devices when mounting several
devices side by side� The environmental conditions must be observed for
every device and, in order to avoid overheating, maintain between them a
minimum distance of 20 mm�
4.2 Remove the device

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5 Electrical connection
5.1 Terminals
Terminals
Plug Terminal Connection
A1 L+ Supply voltage (+ 24 V DC)
protected by a resettable fuse
short-circuit proof, not monitored
S33 Sensor 1 supply (+ 24 V DC)
S35 Sensor 1 GND (0 V DC)
S34 Sensor 1 input

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Plug Terminal Connection
A2 L- Supply voltage (GND)
directly connected to the device ground
S44 Sensor 2 supply (+ 24 V DC)
S45 Sensor 2 GND (0 V DC)
S43 Sensor 2 input
A3 13 Current path 1A (relay contacts)
(not connected)
(not connected)
14 Current path 1B (relay contacts)
C1 Y3 Deactivation of the monitoring function (P) (→ 5.3)
Y4 Deactivation of the monitoring function (N) (→ 5.3)
Y5 Automatic mode selection
Y6 Manual mode selection
C2 Y7 "Fault" transistor output (→ 3.7)
Y8 "Underspeed" transistor output (→ 3.8)
Y1 Feedback circuit output
Y2 Feedback circuit input
C3 23 Current path 2A (relay contacts)
(not connected)
(not connected)
24 Current path 2B (relay contacts)
The relay contacts of the device must be supplied from the same voltage
source�
Observe the technical data of the electrical connections�
(→ 8 Technical data)
PELV power supplies are to be used according to EN 60204-1�
The electrical input signals meet the requirements to EN 61131, type 2�
Do not use unconnected terminals as support point terminal�
Terminal tightening torque: 0�6���0�7 Nm (5���7 lb-in)�

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5.2 Automatic/manual mode selection
If underspeed is detected, the current paths open and the drive is switched off�
The manual operation can prevent the current paths closing automatically as soon
as the input frequency exceeds the Fu value again�
The operating mode is selected via the circuitry of two input terminals Y5 and Y6�
5.2.1 Automatic operation
In this operating mode the device compares the input frequency with the set
switch point�
• If the input frequency is above the switch point Fu, the current paths are closed�
• If the input frequency is below the switch point Fu minus hysteresis, the current
paths are open�
Power
supply
Safety
output
Fu
Fuh
f in
t
ON ON
10 s 10 s
Automatic operation
1: Voltage supply of the unit
2: Current paths (safety-related outputs)
3: Switch point Fu is reached during the start-up delay
4: Switch point Fu is not reached during the start-up delay

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Automatic operation (circuitry of the inputs Y5 and Y6)
The automatic operation mode is implemented by connecting input Y5 to Y1
(pulsed test signal) and input Y6 to + 24 V DC�
If the device detects an error, it returns to the safe state (→ 3.2 Safe state
of the output relays (failsafe state))�
Detected errors are short circuit on 0 V DC or + 24 V DC or separated
connections�
VORSICHT!
Personal injury may result�
Carefully check if the automatic operating mode can be used when
the current paths (safety-related outputs) directly drive a motor�
In some applications an uncontrolled restart may be dangerous�
In these cases the device must be used only as a speed monitor
and not for the direct control of a machine�

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5.2.2 Manual operation
In this operating mode, the outputs of the device are only switched if the input
frequency is above the switch point Fu and after the restart signal has been sent
to the device via an external restart command element�
When the underspeed has been detected, the current paths are open�
Power
supply
Safety
output
Fu
Fuh
f in
t
ON ON
Restart
signal
10 s 10 s
Manual operation
1: Voltage supply of the unit
2: Restart signal
3: Current paths (safety-related outputs)
In manual operation the current path remains open until there is a restart signal on
input Y5� The restart signal is activated via a falling edge on input Y5 (a complete
transition 0 V DC → + 24 V DC → 0 V DC ).
This signal is only active if the frequency exceeds the Fuh value�
The restart signal must be applied for 0�3���5 s� Otherwise the command is
rejected�
If the restart command is activated while the frequency is between Fu and
FuH, the command is rejected� This applies both to the rising and the falling
edge�

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The restart command element must be installed outside the hazardous
area in a position where the hazardous area and the entire work area
concerned are clearly visible�
The device may also be installed within the hazardous area since handling
is not required during operation�
When the device is waiting for the restart command, the yellow LED [ENA]
flashes�
Manual operation (circuitry of the inputs Y5 and Y6)
Manual operation is implemented when during initialisation input Y6 is on the
pulsed test signal of Y1 and input Y5 is open�
The start-up delay of 10 seconds is active after each restart command (→
3�6 Start-up delay)�

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5.3 Enable inputs
If several devices with different switch points are used for underspeed monitoring
of a drive, devices whose switch point value is not relevant can be "switched off"
by means of the two enable inputs�
The monitoring function of these devices is then deactivated; the current paths are
closed�
The monitoring function of a device is activated or deactivated by means of a
complementary signal to both enable inputs�
Enable inputs E1 and E2
1: The monitoring function of the device is active/not active
2: Enable signals not simultaneous
To deactivate the monitoring function of a device 2 conditions must be met:
• The enable signals E1 and E2 have to be activated almost
simultaneously� Max� time interval of the enable signals: 0�5 s
• The device must be switched on when the enable signals are activated�
The enable signals can be activated by means of mechanical switches�

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6 Indicators and operating elements
S2
IN1 IN2
K1 K2
rpm
1
50
100
10
PP Hz
5
96
10
500
0,5 1
S3
FAULTENA
ON CONF
96
3
3
P/0
P/0
S1
1: LEDs
2: Switches (270° potentiometer, 10 positions, locking)
6.1 LEDs
LED Colour Description
ON Green Power
ON when device is switched on�
CONF Blue Configuration
ON when device in configuration mode�
Flashing when switches are in P position�
ENA Yellow Enable
ON when the enable inputs are logically on�
Flashing in configuration mode when the position of a switch is
changed (one flash for each step)�
Flashing when the device is waiting for a restart command (→ 5.2.2)�

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LED Colour Description
FAULT Red Error
ON when an internal fault was detected�
Flashing when an external fault was detected�
1 x Manual/automatic configuration error
2 x Switches in incorrect position (frequency selectors)
3 x Feedback circuit error
4 x Sensor error (function or wiring)
5 x Current > 500 mA on output S33, S44, Y1, Y7 or Y8
Flashing alternately with ENA, CONF, IN1/2 and K1/2 when a sensor
is not connected�
IN1 IN2
K1 K2
FAULTENA
ON CONF
IN1 IN2
K1 K2
FAULTENA
ON CONF
IN1 IN2
K1 K2
FAULTENA
ON CONF
IN1 IN2
K1 K2
FAULTENA
ON CONF
IN1/2 Yellow Input IN1/2
ON when a HIGH signal was detected on the input IN1 or IN2�
K1/2 Green Relay K1/2
ON when the safety output relay K1 or K2 is switched on�
6.2 Switches
Switches Description
S1 SP x 10 Switch point selection (increments of 10)
S2 SP x 1 Switch point selection (increments of 1)
S3 SP multi Unit (rpm/Hz) and multiplier of the selected switch point
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