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

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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

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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.

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1.4 Symbols used
General information
Safety-related information
1.5 Legal notice
W.E.St. Elektronik GmbH
Gewerbering 31
D-41372 Niederkrüchten
Tel.: [phone]
Fax.: [phone]
Home page: www.w-e-st.de
EMAIL: [e-mail]
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.

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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

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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

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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.

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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.