W.E.ST. SCU-138-P Guide

Technical Documentation
SCU-138-P
Speed control unit with integrated power stage

Page 2 of 34 SCU-138-P-2230 05.06.2020
CONTENTS
1General Information.................................................................................................................................................4
1.1 Order number................................................................................................................................................. 4
1.2 Scope of supply.............................................................................................................................................. 4
1.3 Accessories.................................................................................................................................................... 4
1.4 Symbols used................................................................................................................................................. 5
1.5 Legal notice.................................................................................................................................................... 5
1.6 Safety instructions.......................................................................................................................................... 6
2Characteristics.........................................................................................................................................................7
2.1 Device description.......................................................................................................................................... 8
3Use and application.................................................................................................................................................9
3.1 Installation instructions ................................................................................................................................... 9
3.2 Typical system structure............................................................................................................................... 10
3.3 Method of operation...................................................................................................................................... 10
3.4 Commissioning............................................................................................................................................. 11
4Technical description.............................................................................................................................................12
4.1 Input and output signals ............................................................................................................................... 12
4.2 LED definitions ............................................................................................................................................. 12
4.3 Circuit diagram ............................................................................................................................................. 13
4.4 Typical wiring................................................................................................................................................ 14
4.5 Connection examples................................................................................................................................... 14
4.6 Technical data.............................................................................................................................................. 15
5Parameters............................................................................................................................................................17
5.1 Parameter overview...................................................................................................................................... 17
5.2 Basic parameters.......................................................................................................................................... 19
5.2.1 LG (Changing the language).................................................................................................................19
5.2.2 MODE (Parameter view).......................................................................................................................19
5.2.3 SENS (Malfunction monitor) .................................................................................................................19
5.2.4 EOUT (Output signal if not ready).........................................................................................................20
5.3 Input Signal adaptation................................................................................................................................. 20
5.3.1 SELECT:W (command signal source selection) ...................................................................................20
5.3.2 SIGNAL:W (Type of input signal)..........................................................................................................20
5.3.3 SYS_RANGE (Working range) .............................................................................................................21
5.3.4 PWM:ZERO (scaling of the PWM input)...............................................................................................21
5.3.5 PWM:FULL...........................................................................................................................................21
5.3.6 FIX_SPEED (Internal demand value) ...................................................................................................21
5.3.7 RA (Command signal ramp time)..........................................................................................................22
5.4 Control parameters....................................................................................................................................... 23
5.4.1 PID controller........................................................................................................................................23
5.4.2 Integrator control function.....................................................................................................................24
5.5 Output signal adaptation............................................................................................................................... 25
5.5.1 MIN (Deadband compensation)............................................................................................................25
5.5.2 MAX (Output scaling)............................................................................................................................25
5.5.3 TRIGGER (Response threshold for the MIN parameter) ......................................................................25
5.5.4 SIGNAL:U (Output polarity) ..................................................................................................................26
5.6 Power stage.................................................................................................................................................. 27
5.6.1 CURRENT (Rated solenoid current).....................................................................................................27
5.6.2 DFREQ (Dither frequency)....................................................................................................................27
5.6.3 DAMPL (Dither amplitude)....................................................................................................................27
5.6.4 PWM (PWM Frequency).......................................................................................................................28
5.6.5 ACC (Current loop auto adjustment).....................................................................................................28

Page 3 of 34 SCU-138-P-2230 05.06.2020
5.6.6 PPWM (P gain of the current loop) ...................................................................................................... 28
5.6.7 IPWM (I gain of the current loop)......................................................................................................... 28
5.7 Special commands ....................................................................................................................................... 29
5.7.1 AINMODE (Scaling mode)................................................................................................................... 29
5.7.2 AIN (Analogue input scaling)................................................................................................................ 30
5.8 PROCESS DATA (Monitoring)...................................................................................................................... 31
6Appendix............................................................................................................................................................... 32
6.1 Failure monitoring......................................................................................................................................... 32
6.2 Troubleshooting............................................................................................................................................ 32
6.3 Description of the command structure.......................................................................................................... 33
7Notes.................................................................................................................................................................... 34

Page 4 of 34 SCU-138-P-2230 05.06.2020
1 General Information
1.1 Order number
SCU-138-P - Speed control unit with integrated power stage and pulse transmitter input
1.2 Scope of supply
The scope of supply includes the module plus the terminal blocks which are part of the housing.
The Profibus plug, interface cables and further parts which may be required should be ordered separately.
This documentation can be downloaded as a PDF file from www.w-e-st.de.
1.3 Accessories
WPC-300 - Start-Up-Tool (downloadable from our homepage –products/software)
Any standard cable with USB-A and USB-B connector can be used as the programming cable.

Page 5 of 34 SCU-138-P-2230 05.06.2020
1.4 Symbols used
General information
Safety-related information
1.5 Legal notice
W.E.St.
Elektronik GmbH
Gewerbering 31
D-41372 Niederkrüchten
Tel.: +49 (0)2163 577355-0
Fax.: +49 (0)2163 577355-11
Home page: www.w-e-st.de
EMAIL: contact@w-e-st.de
Date: 05.06.2020
The data and characteristics described herein serve only to describe the product. The user is required to
evaluate this data and to check suitability for the particular application. General suitability cannot be inferred
from this document. We reserve the right to make technical modifications due to further development of the
product described in this manual. The technical information and dimensions are non-binding. No claims may
be made based on them.
This document is copyright.

Page 6 of 34 SCU-138-P-2230 05.06.2020
1.6 Safety instructions
Please read this document and the safety instructions carefully. This document will help to define the product
area of application and to put it into operation. Additional documents (WPC-300 for the start-up software) and
knowledge of the application should be taken into account or be available.
General regulations and laws (depending on the country: e. g. accident prevention and environmental
protection) must be complied with.
These modules are designed for hydraulic applications in open or closed-loop control circuits.
Uncontrolled movements can be caused by device defects (in the hydraulic module or the
components), application errors and electrical faults. Work on the drive or the electronics must
only be carried out whilst the equipment is switched off and not under pressure.
This handbook describes the functions and the electrical connections for this electronic
assembly. All technical documents which pertain to the system must be complied with when
commissioning.
This device may only be connected and put into operation by trained specialist staff. The
instruction manual must be read with care. The installation instructions and the commissioning
instructions must be followed. Guarantee and liability claims are invalid if the instructions are
not complied with and/or in case of incorrect installation or inappropriate use.
CAUTION!
All electronic modules are manufactured to a high quality. Malfunctions due to the failure of
components cannot, however, be excluded. Despite extensive testing the same also applies
for the software. If these devices are deployed in safety-relevant applications, suitable external
measures must be taken to guarantee the necessary safety. The same applies for faults which
affect safety. No liability can be assumed for possible damage.
Further instructions
The module may only be operated in compliance with the national EMC regulations. It is
the user’s responsibility to adhere to these regulations.
The device is only intended for use in the commercial sector.
When not in use the module must be protected from the effects of the weather,
contamination and mechanical damage.
The module may not be used in an explosive environment.
To ensure adequate cooling the ventilation slots must not be covered.
The device must be disposed of in accordance with national statutory provisions.

Page 7 of 34 SCU-138-P-2230 05.06.2020
2 Characteristics
This module was developed for controlling a universal closed loop control system for speed and velocity con-
trol. A power amplifier for proportional valves is integrated. Various parameter settings allow an optimal adap-
tation to the corresponding valve. The controller runs with a loop time of 1 ms and the amplifier with 0,125 ms
for the current control.
The command value is received by an analogue input signal (range 0… 10V or 4… 20mA). Alternatively the
setpoint can be defined by an internal parameter (e.g. for generator speed control). Another possibility is the
use of a PWM modulated signal for the transmittal of the command value.
Ramp function and PID controller can be used universally. The output current is closed loop controlled and
therefore independent from the supply voltage and a varying solenoid resistance. The output stage is moni-
tored (short circuit / broken wire) and switches off in case of detected error.
By the free parameterization of the power stage all typical proportional valves of the different manufactures
can be optimal adapted.
Because of the easy handling a very short training period is guaranteed.
Typical applications: Speed control using an impulse sensor.
Features
Universal speed control unit
Compact housing
Digital reproducible adjustments
Free scaling of the analogue command input
Alternatively scalable PWM command input
Universal PID controller
Controlling of proportional valves with one or two solenoids
Direct connection of pulse transmitter
Free parameterization of ramps, MIN and MAX, DITHER (frequency and amplitude) and
PWM frequency of the solenoid output
Output current up to 2.6 A
Adaptable to all standard proportional valves
Application orientated parameter settings
Fault diagnosis and extended function checking
Parameterization via USB interface with WPC-300 software

Page 8 of 34 SCU-138-P-2230 05.06.2020
2.1 Device description
V:
ID:
Add.:Date:
Made in Germany
W.E.ST.
Ready
1 2 3 4
5 6 7 8
910 11 12
14 15 1613
D-41372 Niederkrüchten
Homepage: http://www.w-e-st.de
W.E.ST.
Elektronik
13 14 15
910 11 12
16
A B
Klemmblöcke (steckbar)
Terminals (removable)
LEDs
USB
Interface
Typenschild undAnschlussbelegung
Type plate and terminal pinassignment
23,0000 mm99,0000 mm
114,0000 mm

Page 9 of 34 SCU-138-P-2230 05.06.2020
3 Use and application
3.1 Installation instructions
This module is designed for installation in a shielded EMC housing (control cabinet). All cables which
lead outside must be screened; complete screening is required. It is also necessary to avoid strong
electro-magnetic interference sources being installed nearby when using our open and closed loop
control modules.
Typical installation location: 24 V control signal area (close to PLC)
The devices must be arranged in the control cabinet so that the power section and the signal section
are separate from each other.
Experience shows that the installation place close to the PLC (24 V area) is most suitable. All digital
and analogue inputs and outputs are fitted with filters and surge absorbers in the device.
The module should be installed and wired in accordance with the documentation bearing in mind EMC
principles. If other consumers are operated with the same power supply, a star-shaped ground wiring
scheme is recommended. The following points must be observed when wiring:
The signal cables must be laid separately from power cables.
Analogue signal cables must be screened.
All other cables must be screened if there are powerful interference sources (frequency
converters, power contactors) and cable lengths > 3 m. Inexpensive SMD ferrites can be
used with high-frequency radiation.
The screening should be connected to PE (PE terminal) as close to the module as
possible. The local requirements for screening must be taken into account in all cases. The
screening should be connected to at both ends. Equipotential bonding must be provided
where there are differences between the connected electrical components.
If having longer lengths of cable (> 10 m), the diameters and screening measures should
be checked by specialists (e. g. for possible interference, noise sources and voltage drop).
Special care is required if using cables of over 40 m in length, and if necessary the
manufacturer should be consulted if necessary.
A low-resistance connection between PE and the mounting rail should be provided. Transient
interference is transmitted from the module directly to the mounting rail and from there to the local
earth.
Power should be supplied by a regulated power supply unit (typically a PELV system complying with
IEC364-4-4, secure low voltage). The low internal resistance of regulated power supplies gives better
interference voltage dissipation, which improves the signal quality of high-resolution sensors in
particular. Switched inductances (relays and valve coils) which are connected to the same power
supply must always be provided with appropriate overvoltage protection directly at the coil.

Page 10 of 34 SCU-138-P-2230 05.06.2020
3.2 Typical system structure
This minimal system consists of the following components:
(*1) Proportional valve
(*2) Pulse transmitter
(*3) Speed control unit SCU-138-P
(*4) Interface to PLC
3.3 Method of operation
This speed control module is controlled via an analogue command signal (from plc, joystick or potentiometer),
a PWM Signal or a fix programmed command value. An ENABLE signal (24 V typical) activates the functions
and if error-free operation this is reported via a READY output. Now the device is in power amplifier mode.
The control loop is initiated by a digital START input. Therefore, the actual value is read by an encoder. If us-
ing two solenoids the closed loop controller gets activated directly with the ENABLE signal. The digital START
input is used for switching the solenoids in this mode (DIR).
The integrated standard features are configured on the various parameters.
In case of a fault the power output stage will be deactivated and the fault will be indicated via deactivating the
READY output and the flashing READY LED.
Three different modes can be used for the error management. SENS=ON: all faults have to be acknowledged
by the ENABLE input. SENS=AUTO: automatic reset mode for all signal faults. SENS=OFF: fault detection is
suppressed.
The output current is controlled whereby a high accuracy and a good dynamic will be obtained. All customary
proportional valves (up to 2.6 A) could be controlled with this power amplifier.

Page 11 of 34 SCU-138-P-2230 05.06.2020
3.4 Commissioning
Step
Task
Installation
Install the device in accordance with the circuit diagram. Ensure it is wired cor-
rectly and that the signals are well shielded. The device must be installed in a
protective housing (control cabinet or similar).
Switching on for the first time
Ensure that no unwanted movement is possible in the drive (e. g. switch off the
hydraulics). Connect an ammeter and check the current consumed by the de-
vice. If it is higher than specified, there is an error in the wiring. Switch the de-
vice off immediately and check the wiring.
Setting up communication
Once the power input is correct the PC (notebook) should be connected to the
serial interface. Please see the WPC-300 program documentation for how to
set up communication.
Further commissioning and diagnosis are supported by the operating software.
Pre-parameterization
Parameterize now (with the help of the system redundancy and the connection
diagram) the following parameters:
The WORKING RANGE for the ANALOGUE INPUTS. See specifications of the
system and the sensors.
The output CURRENT and the typical valve parameters like DITHER and
MIN/MAX.
Pre-parameterization is necessary to minimize the risk of an unintentional
movement / pressure.
Control signal
Check the control signal (output signal). The control signal (solenoid current)
lies in the range of 0... 2.6 A. In the current state it should show around 0 A.
Switching on the hydraulics
The hydraulics can now be switched on. The module is not yet generating a
signal. Drives should be at a standstill or drift slightly (leave its position at a
slow speed).
Activating ENABLE
CAUTION! The power stage gets activated.
The controller can now be driven by the analogue command value or preset fix
rounds per minute.
Activating START
The actual value is read in now and the output signal is calculated depending
on the control deviation and the controller settings.
Controller optimization
Now optimize the settings. The PID parameters have to be adapted depending
on the application.

Page 12 of 34 SCU-138-P-2230 05.06.2020
4 Technical description
4.1 Input and output signals
4.2 LED definitions
LEDs
Description of the LED function
GREEN
Identical to the READY output.
OFF: No power supply or ENABLE is not activated
ON: System is ready for operation
Flashing: Error discovered
YELLOW A
Intensity of the solenoid current
GREEN +
YELLOW A
1. Chasing light (over all LEDs): The bootloader is active. No normal functions are
possible.
2. All LEDs flash shortly every 6 s: An internal data error was detected and corrected
automatically! The module still works regularly. To acknowledge the error the module
has to be cycle powered.
YELLOW A +
YELLOW B
Both yellow LEDs flash oppositely every 1 s: The nonvolatile stored parameters are in-
consistent! To acknowledge the error, data has to be saved with the SAVE command or
the corresponding button in the WPC.
Connection
Supply
PIN 7
Power supply (see technical data)
PIN 8
0 V (GND) connection.
Connection
Analogue signals
PIN 9 / 10
Command value (WA), signal range 0… 10 V or 4… 20 mA, scalable, alternatively PWM
signal
PIN 13 /14
Feedback value (X), the actual speed is read in via a pulse transmitter (12 / 24 V)
PIN 11
0 V (GND) connection for analogue signals
PIN 12
8V reference voltage output
Connection
Solenoids
PIN 2 / 1
PWM output solenoid B
PIN 3 / 4
PWM output solenoid A
Connection
Digital inputs and outputs
PIN 15
ENABLE input:
Generally enabling of the application.
Erases error messages, activates the power stage and the READY signal.
PIN 6
START (DIR) input:
ON: Closed loop control mode, the PID controller is activated
OFF: Open loop amplifier mode, pure power amplifier
PIN 5
READY output:
ON: The module is enabled; there are no discernable errors.
OFF: ENABLE is not available, no supply or an error has been detected.

Page 13 of 34 SCU-138-P-2230 05.06.2020
4.3 Circuit diagram
2
Input
PE via DIN-RAIL
3
4
1
5
15
Ready
Enable
Start (DIR)
Digital Output
USB type B
SCU-138-P
6
13
Valve
adaption
Digital Input
u
Control program
Ramp
function PID
control
function
ia
ib
to solenoidA
c
wa
x
12
GND
+Ub
8
7
DC
DC
to solenoid B
Power
supply
Power
stage
Digital Input
Reference
voltage
14
11
Setpoint
Actual
value
Scaling
Frequency
Input
Scaling
9
10
Differetial Input
we
+
-

Page 14 of 34 SCU-138-P-2230 05.06.2020
4.4 Typical wiring
4.5 Connection examples
8V PIN 12
GND PIN 11
+In PIN 9
-In PIN 10
Potentiometer / Joystick
+In PIN 9
-In PIN 10
SPS / PLC / SENSOR 0... 10 V
8V PIN 12
GND PIN 11
+In PIN 9
-In PIN 10
Joystick
4... 20 mA input
+In PIN 9
-In PIN 10
GND PIN 11
Alternative 3 –wire connection of two solenoids:
Enable
8765
16151413
1211109
Analogue command signal
Solenoid
4321
0V
PE
Power Supply
0V
12 V / 24 V
+
-
Pulse signal (actual value)
+
Reference voltage output
Ready
A
Solenoid B
Start (DIR)
Digital input
output
PE
0V
0V
Example.: Hawe valves
3
4
1
2
A-Solenoid
B-Solenoid

Page 15 of 34 SCU-138-P-2230 05.06.2020
4.6 Technical data
Supply voltage (Ub)
Current requirement
External protection
[VDC]
[mA]
[A]
12… 30 (incl. ripple)
30 + solenoid current
3 medium time lag
Reference output
Voltage
Max. load
[V]
[mA]
8
25
Digital inputs
OFF
ON
Input resistance
[V]
[V]
[kOhm]
< 2
> 10
25
Digital outputs
OFF
ON
Max. output current
[V]
[V]
[mA]
< 2
max. Vcc
50
Analog inputs:
Voltage
Input resistance
Current
Burden
Signal resolution
[V]
[kOhm]
[mA]
[Ohm]
[%]
0… 10
min. 90
4… 20
390
0,03
PWM input (command value)
[V]
[Hz]
Logic 0: < 2 V
Logic 1: > 10 V, max. 1 mA
50… 1000
Pulse input (actual value)
[V]
[Hz]
Logic 0: < 2 V
Logic 1: > 10 V, max. 1 mA
35… 10000 (measurement value limited to 6
kHz)
PWM output
Max. output current
Frequency
[A]
[Hz]
Wire break and short circuit monitored
2,6
61… 2604 selectable in defined steps
Controller cycle times
Solenoid current control
Signal processing
[µs]
[ms]
125
1
Serial interface
Transmission rate
-
[kBaud]
USB - virtual COM Port
9,6… 115,2
Housing
Material
Flammability class
Snap-on module acc. EN 50022
PA 6.6 polyamide
V0 (UL94)
Weight
[kg]
0,13
Protection class
Temperature range
Storage temperature
Humidity
Vibration resistance
[IP]
[°C]
[°C]
[%]
-
20
-20… 60
-20… 70
< 95 (non-condensing)
IEC 60068-2-6 (Category C)

Page 17 of 34 SCU-138-P-2230 05.06.2020
5 Parameters
5.1 Parameter overview
Group
Command
Default
Unit
Description
Basic parameters
LG
EN
-
Changing language help texts
MODE
STD
-
Parameter view
SENS
ON
-
Malfunction monitor
EOUT
0
0.01 %
Output signal if not ready
Input signal adaptation
Command signal scaling
SELECT:W
ANA
-
Selection of the command value source
SIGNAL:W
U0-10
-
Type of input
SYS_RANGE
1000
Hz
Working range / reference value for 100% command value
PWM:ZERO
0
0,01 %
PWM duty cycle yielding a setpoint of 0%
PWM:FULL
10000
0,01 %
PWM duty cycle yielding a setpoint of 100%
FIX_SPEED
0
0.01 %
Fix internal command value
Ramp function
RA:UP
RA:DOWN
100
100
ms
ms
Command signal ramp times
Control parameters
PID controller
C:P
C:I
C:D
C:D_T1
C:FF
100
4000
0
500
0
0.01
0.1 ms
0.1 ms
0.1 ms
0.01 %
P gain
I gain
D gain
D gain filter
Feed forward gain
Integrator control
C:I_ACT
C:I_LIM
C:I_PRE
2500
2500
0
0.01 %
0.01 %
0.01 %
Integrator activation
Integrator limitation
Integrator pre-set value
Output signal adaptation
MIN:A
MIN:B
0
0
0.01 %
0.01 %
Deadband compensation
MAX:A
MAX:B
10000
10000
0.01 %
0.01 %
Output scaling
TRIGGER
200
0.01 %
Deadband compensation trigger point
SIGNAL:U
1S+
-
Type and polarity of the output / controller

Page 18 of 34 SCU-138-P-2230 05.06.2020
Group
Command
Default
Unit
Description
Parameters of the power stage
CURRENT
1000
mA
Rated solenoid current
DFREQ
121
Hz
Dither frequency
DAMPL
500
0.01 %
Dither amplitude
PWM
2604
Hz
PWM frequency
ACC
ON
-
Current loop auto adjustment
PPWM
IPWM
7
40
-
-
P-Gain of the current loop
I-Gain of the current loop
Special commands
Scaling mode
AINMODE
EASY
-
Input scaling mode
AIN:W
A: 1000
B: 1000
C: 0
X: V
-
-
0.01 %
-
Free scaling of the analogue input. Gets activated when
AINMODE is switched over to MATH.

Page 19 of 34 SCU-138-P-2230 05.06.2020
5.2 Basic parameters
5.2.1 LG (Changing the language)
Command
Parameters
Unit
Group
LG x
x= DE|EN
-
STD
Either German or English can be selected for the help texts.
CAUTION: After changing the language settings, the ID button in the menu bar (WPC-300) must be
pressed (module identification).
5.2.2 MODE (Parameter view)
Command
Parameters
Unit
Group
MODE x
x= STD|EXP
-
STD
This command changes the operating mode. Various commands (defined via STD/EXP) are blanked out in
Standard Mode. The commands in Expert Mode have a more significant influence on system behavior and
should accordingly be changed with care.
5.2.3 SENS (Malfunction monitor)
Command
Parameters
Unit
Group
SENS x
x= ON|OFF|AUTO
-
STD
This command is used to activate/deactivate the monitoring functions (4… 20 mA sensors, output current, sig-
nal range and internal failures) of the module.
ON: All monitoring functions are active. Detected failures can be reset by deactivating the ENABLE in-
put.
OFF: No monitoring function is active.
AUTO: Auto reset mode. All monitoring functions are active. If the failure doesn’t exist anymore, the mod-
ule automatically resumes to work.
Normally the monitoring functions are always active because otherwise no errors are detectable via
the READY output. Deactivating is possible mainly for troubleshooting.

Page 20 of 34 SCU-138-P-2230 05.06.2020
5.2.4 EOUT (Output signal if not ready)
Command
Parameters
Unit
Group
EOUT X
x= 0… 10000
0.01 %
EXP
Output value in case of a detected error or a deactive ENABLE input. A value (degree of valve opening) for
use in the event of a sensor error (or the module is disabled) can be defined here. This function can be used if,
for example, in case of an error of the setpoint signal the valve should be driven with a fixed current.
|EOUT| = 0 The output is switched off in the event of an error. This is normal behavior.
Inpenpendetly from the setting of the parameter SIGNAL:U the EOUT –Signal will always be applied to Sole-
noid A. No inversion or change to Solenoid B will occur. Solenoid B is always turned off in case of an error.
CAUTION!
The output value defined here is stored permanently (independently of the parameter set). The
effects should be analyzed by the user for each application from the point of view of safety.
5.3 Input Signal adaptation
5.3.1 SELECT:W (command signal source selection)
Command
Parameters
Unit
Group
SELECT:W X
x= ANA|PWM|PRE
-
STD
By this command the source for the command value is set.
- ANA: The command value is read in via an analogue signal, which is defined by SIGNAL:W.
- PWM: The command value is read in via a pulse width modulated signal at the input.
- PRE: The command value is pre-set with parameter FIX_SPEED.
5.3.2 SIGNAL:W (Type of input signal)
Command
Parameters
Unit
Group
SIGNAL:W X
x= OFF|U0-10|I4-20
-
EASY
This command can be used to set the type of the analogue input signal (voltages or current) and to define the
direction of the signal.
OFF= Deactivation of the input
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