Technical documentation

W.E.ST. Elektronik GmbH
Technical documentation
POS-123A / POS-123I

W.E.ST. Elektronik GmbH
Table of contents
Revisions ...................................................................................................................................................... 3
Ordering code ............................................................................................................................................... 3
Accessories .................................................................................................................................................. 3
General description....................................................................................................................................... 4
General installation remarks......................................................................................................................... 5
Description of the unit................................................................................................................................... 6
Typical positioning ............................................................................................................................. 6
In- and outputs ..................................................................................................................................... 7
LED Function ....................................................................................................................................... 7
Block diagram ...................................................................................................................................... 8
Typical wiring ....................................................................................................................................... 9
Technical Data ................................................................................................................................... 10
Dimensions ...................................................................................................................................... 10
General IO description ....................................................................................................................... 11
Power supply ................................................................................................................................... 11
Digital inputs .................................................................................................................................... 11
Digital outputs .................................................................................................................................. 11
Analogue inputs ............................................................................................................................... 12
Analogue outputs............................................................................................................................. 12
Serial interface................................................................................................................................. 13
Start-up and commissioning guidelines...................................................................................................... 14
Parameter table .......................................................................................................................................... 15
Parameter description................................................................................................................................. 16
AIN (input signal scaling) ................................................................................................................. 16
A (acceleration time)........................................................................................................................ 16
D (deceleration stroke or braking distance).....................................................................................17
CTRL (braking characteristics) ........................................................................................................ 17
VELO (Internal velocity preset)........................................................................................................ 18
VS (internal or external velocity preset)........................................................................................... 18
VRAMP (ramp time for the external velocity) .................................................................................. 18
VMODE (Activation of the NC mode) .............................................................................................. 18
TH (Stroke time for the speed controlled axis) ................................................................................ 19
HAND (Hand speed)........................................................................................................................ 19
MIN (compensation of the dead zone) ............................................................................................ 20
MAX (maximum output signal)......................................................................................................... 20
TRIGGER (threshold value of MIN)................................................................................................. 20
INPOS (in positioning window) ........................................................................................................ 21
OFFSET (zero point adjustment)..................................................................................................... 21
POL (output polarity)........................................................................................................................ 21
SENS (sensor monitoring) ............................................................................................................... 21
SAVE (data storing in EEPROM)..................................................................................................... 21
LOADBACK (copy of the EEPROM into the active RAM) ............................................................... 22
DEFAULT (parameter reset)............................................................................................................ 22
PROCESS DATA (monitoring) ........................................................................................................ 22
Appendix: Power stage (PEXT3)................................................................................................................ 23
Remarks ..................................................................................................................................................... 24
Seite 2 von 24

Revisions
W.E.ST. Elektronik GmbH
Date Module revision Comment
14.02.2006 1113 rev 1 New hardware based on the ME5 board.
27.04.2007 1113 rev 2 Software adaptation of the 4… 20 mA output
14.05.2008 1113 rev 3
Ordering code
POS-123A-11* - with analogue ± 10 V output
POS-123I-11* - with analogue 4… 20 mA output
The working direction of the sensor signal is changeable.
AIN:X -1000 1000 10000 V or AIN:X -1250 1000 10000 C
will invert the working range.
Optional
POS-123P - with integrated power stage
POS-123PDP - with integrated Profibus PD and SSI sensor interface (see doc. POS-123PDP)
* = Version number, for ordering not necessary. Changes of the last digit (13 to 14) indicate technical improvements
at 100% compatibility. Changes from 13 to 20 indicate significant technical improvements. In
this case check the documentation about the parameter and wiring.
Accessories
RS232-SO - programming cable with RS232C interface
USB-SO - programming cable with USB interface
HHT-302 - Hand held terminal
WPC-300 - Start up software
W.E.ST. Elektronik GmbH
Poststraße 26
D-41372 Niederkrüchten
Fax.: +49 (0) 2163 57 73 55 - 11
Homepage: www.w-e-st.de or www.west-electronics.com
EMAIL: info@w-e-st.de
Date: 14.04.2008
Revision: 9
The right of changes are reserved.
Seite 3 von 24

General description
W.E.ST. Elektronik GmbH
This electronic module is developed for controlling of hydraulic positioning drives. A typical signal accuracy
of app. 0,01% of the sensor stroke can be achieved. The sampling time of the control loop is 1ms.
Proportional valves with integrated electronics or external power amplifiers can be controlled by the analogue
differential output (or by the 4… 20 mA current output). Additionally an integrated power amplifier
for best performance is available.
Internal profile generation (acceleration time, max. velocity and stroke depended deceleration) provides
fast and excellent positioning. Two modes can be selected.
Stroke depended deceleration: The axis drives in open loop mode and is switched over in closed loop
during deceleration. This is a time-optimal positioning structure with very high stability. The maximal velocity
can be limited by the external velocity input.
NC mode: An integrated NC profile generator (VMODE command) can be activated. The position profile
is internally generated with defined speed and the axis is following (controlled by the following error) the
command position with the same speed.
Internal functions, InPos, out of stroke and sensor or command failure are monitored by the two digital
outputs: ready and status.
The adjustment via RS232C is simple and easy to understand. A standard terminal program or our special
windows application software (WPC-300, download from our homepage) can be used.
Typical applications: positioning drives, handling axis and fast transportable drives (adaptation of nonlinear
valve characteristics).
Features
• Extern definable target positions
• High speed positioning mode
• Principle of stroke depended deceleration or NC controlled movement
(speed controlled)
• Optimal use of overlapped and zero overlapped proportional valves
• Internal profile, defined by acceleration time, max velocity and deceleration
stroke
• Extern definable velocities
• Simple and application orientated parameter settings
• Failure monitoring
• Adjustments via RS232C interface
Seite 4 von 24

General installation remarks
Explanation of terms and notes on safety
Terms:
w: command signal
x: actual signal
v external speed
xw: error between w and x (x- w)
u: output signal
W.E.ST. Elektronik GmbH
Mounting instructions
This module is for the installation provided in shielded electromagnetic compatibility housing (EMC conform).
All cables operating outside have to be screened. A complete shielding is presupposed. By use of our
control modules it is also presupposed, that no strong electrical disturbances near the module are installed.
Typical mounting area: 24V control signal area (near PLC)
By the arrangement of the electrical cabinet a separation between power part (and power cables) and
signal part must be taken in consideration. Experience shows us that the area next to the PLC (24 V
area) is suitable. All digital and analogue inputs and outputs have filters and an over voltage protection. In
case of correct wiring and shielding all EMC demands are fulfilled. If there are nevertheless any problems,
please send us detailed sketches of mounting and wiring. We will look after this problem immediately.
Even if all EMC-norms are fulfilled, technical problems in special cases are possible. Our experience has
shown us that most of these problems are caused in the physical conditions of the cables. If everything is
shielded continuously and configured correctly, no problems have to be expected.
ATTENTION!
ATTENTION!
Due to electrical disturbances, failure at components as well as software faults can cause
in individual cases uncontrolled movements at the drive. Appropriate safety precautions
have to be considered during the engineering.
Connection and start up of the module may only be allowed by qualified persons
who have, because of education, experience and instruction, sufficient
acknowledge on relevant directives and approved technical rules. Please
read and follow the operating instructions carefully. In case of non observance
of the instruction the guaranty and liability claim expires.
Seite 5 von 24

Description of the unit
Typical positioning
W.E.ST. Elektronik GmbH
This module supports the simple point-to-point positioning with hydraulic drives. The system works with
the principle of stroke depended deceleration, that means the control gain will be adjusted with the parameters
D:A and D:B.
The deceleration characteristics can be defined with the parameter CTRL linear (LIN) or nearly square
root (SQRT1). By use of standard proportional valves, SQRT1 has to be chosen normally.
By use of control valves with linear characteristics, it depends on the application. If you choice LIN, a
shorter deceleration stroke can be set (D:A and D:B).
Sequence of the positioning:
The positioning process will be controlled by switching inputs. After enabling (ENABLE input), the command
position is set to the actual position of the sensor and the axis is in closed loop position control
mode. The READY output indicates a general ready for operation. With START input, the analogue
command input (Pin 13) is active and new command positions will be taken over. The axis is immediately
driving to this new position and indicates, with the InPos output, when the axis is in position. The InPos
output is active as long as the axis is within the InPos window or the START input is active.
The axis can be driven in manual mode (START is off) with the digital inputs HAND+ or HAND-. The programmed
velocity (parameter HAND) is used.
When the HAND inputs are switched off, the command position is set to the actual position and the system
is in closed loop position control mode.
Weak points of positioning accuracy:
The positioning accuracy will almost be limited by the hydraulics and mechanics. Therefore, the correct
valve selection is the most important point. Additionally, two contradictory requirements (short positioning
time and high accuracy) have to be considered in the system design.
v+
v-
MAX:A
A:A D:A
D:B
Volumenstrom P-A und B-T
Regelrichtung
Ausfahren
Regelrichtung
Einfahren
MAX:B
Seite 6 von 24
A:B

In- and outputs
W.E.ST. Elektronik GmbH
Terminal Description of the analogue inputs and outputs
PIN 9/10 External command speed (V), range 0… 100 % corresponds to 0… 10 V
PIN 6 -
PIN 13 Command position (W), range 0… 100% corresponds to 0… 10V or 4… 20 mA
PIN 14 Actual (feedback) value (X), range 0… 100% corresponds to 0… 10V or
4… 20 mA
PIN 15 / 16 Differential output (U) ± 100% corresponds to ± 10V differential voltage,
optionally (I-version) current output ±100% corresponds to 4… 20 mA (PIN 15 to
PIN 11)
Terminal Description of the digital inputs and outputs
PIN 8 Enable input:
This digital input signal initializes the application. The analogue output is active
and the READY signal indicates that all components are working correctly. Target
position is set to actual position and the drive is closed loop controlled.
PIN 7 START (RUN) input:
The positioning controller is active; the external analogue command position is
taken over as command value. If the input is switched off during movement the
command position is set to the actual position plus a defined emergency deceleration
stroke
PIN 6 HAND+ input:
Hand mode (START = OFF), driving with the programmed velocity. After deactivation
the actual value is taken over as command position.
PIN 5 HAND- input:
Hand mode (START = OFF), driving with the programmed velocity. After deactivation
the actual value is taken over as command position.
PIN 2 STATUS output:
Monitoring of the control error (INPOS). Depending on the INPOS command, the
status output will be deactivated, if the position difference is greater then the adjusted
window.
The output is only active if START = ON.
PIN 1 READY output:
General operationality, ENABLE is active and there is no sensor error (by use of
4… 20 mA sensors). This output corresponds with the green LED.
LED Function
LEDs Description of the LED function
GREEN Identical with the READY output.
OFF: No power or ENABLE is inactive.
ON: System in process
FLASHING Failure detected (internal or 4… 20 mA).
Only if SENS = ON.
YELLOW Identical with the STATUS output.
OFF: Control error depending of the error parameter.
ON: No control error.
Seite 7 von 24

Block diagram
POS-123
3,5 mm JISC-6560
Ramp time
24V
3
24 V
DC
10
9
0..10V
command speed
4
0 V
RS232 C
9600 Baud
1 Stopbit
no parity
V
vramp x
x = 1...2000
0V
DC
0 V
0 V
11
Power supply
W.E.ST. Elektronik GmbH
Differential input
of the actuator
Acceleration A
Deceleration A
Input selector
13
15
Output: A (0..10)V
a:i x
i = A
x = 1...2000 ms
d:i x
i = A
x = 10...10000
ain:i a b c x
i = W
0..10V
4..20mA
Command
position
16
a,b,c = -10000...10000
x = V|C
11
0 V
0 V
Output: B (0..10)V
a:i x
i = B
x = 1...2000 ms
d:i x
i = B
x = 10...10000
14
12
Valve adaptation
vs x
x = EXT | INT
velo x
x = 1000...10000
min:i x
i = A|B
x = 0..5000
max:i x
i = A|B
x = 5000..10000
trigger x
x = 0..2000
pol x
x = +|-
offset x
x = -2000... 2000
XW
W
U
Input selector
X
ain:i a b c x
i = X
0..10V
4..20mA
Feedback
position
Acceleration B
Deceleration B
a,b,c = -10000...10000
x = V|C
11
Seite 8 von 24
I version: 4... 20 mA output
PIN 15 to PIN 12
0 V
0 V
Ready
1
24 V output
Control program
24 V input
8
Enable
InPos
2
24 V output
24 V input
7
Start
PE via DIN-RAIL
SUPPORT DIAGNOSTICS CONFIGURATION
save din inpos x (x = 0..2000)
loadback x ctrl x (x = LIN|SQRT1|SQRT2)
help w sens x (x = ON|OFF)
para xw hand:i x (i = A|B, x = -10000..10000)
default u vmode x (x = ON|OFF)
v th x (x = 100...60000)
24 V input
6
Hand +
24 V input
5
Hand -

Typical wiring
PLC Inputs
PLC Outputs
analogue command
signal from PLC
Error / InPos
Ready
Enable
Start
Hand+
Hand-
Actual position
0..10V
W.E.ST. Elektronik GmbH
PE terminal
1
5
9
13
0..10V
0V
2
6
10
14
3
7
11
15
4
8
12
16
Seite 9 von 24
PE terminal
0V
0..10V
0..10V
Screen
24V
0V
Power supply
To the power amplifier or valve
with integrated electronics.
Differential input is required.
(-10V..10V)
4... 20 mA output:
PIN 15 to PIN 12

Technical Data
Power supply
Current consumption
External fuse
Dimensions
WIDTH (see technical data)
W.E.ST. Elektronik GmbH
[VDC]
[mA]
[A]
Digital inputs [V]
[V]
Digital outputs [V]
[V]
Analogue inputs (sensor and command
signals)
Resolution
Speed input
Resolution
Analogue outputs
Max. load
Resolution
[V]
[mA]
[%]
[V]
[%]
[V]
[mA]
[mA]
[%]
Sample time ms 1
Seite 10 von 24
12… 30 (incl. ripple)
12 V
logic 0: < 2 V
logic 1: > 12 V (50 mA)
0...10; 33 kOhm
4...20; 250 Ohm
0,01 (internally 0,0031)
0...10; 90 kOhm
0,01
2 x 0...10 (differential output)
5
4...20 mA (I version); 390 Ohm max. load
0,024
Interface RS 232C, 9600 Baud, 1 stopbit, No parity, Echo
Mode
Housing Snap-On Module EN 50022
Polyamide PA 6.6
Combustibility class V0 (UL94)
Protection class
Temperature range
Humidity
[IP]
[°C]
[%]
Dimensions (width) [mm] 22,5
20
-20… 60

W.E.ST. Elektronik GmbH
General IO description
This description is a general description of the technical data of out open loop and closed loop control
modules. Please check the implemented IO signals via the block diagram about availability.
Power supply
This module is designed for 12… 30 VDC (typical 24 V) of a power supply. This power supply must correspond
to the actual EMC standards.
All inductivities at the same power supply (relays, valves …) must be provided with an over voltage protection
(varistors, free-wheel diodes …).
It is recommended to use a regulated power supply (linear or switching mode) for the supply of the module
and the sensors. These power supplies have a clearly lower internal resistance in comparison with
non regulated power supplies and therefore a better spurious rejection.
Power supply : 12… 30 VDC, incl. ripple
Power consumption: 100 mA
External protection: 1 A medium lag
ATTENTION: Without an external fuse and in case of a continual short-circuit the
module can be destroyed in spite of all internal protections.
Digital inputs
The digital inputs are designed for a voltage level of 12 V and 24 V. The typical connections to the PLC
will not be screened if the modules are arranged carefully and with short cable lengths. As common potential
0V (PIN 4) is used.
All inputs are protected with suppressor diodes and RC-filters against transient overshoots.
Low level: < 4 V
High level: > 12 V
Current: < 0,1 mA
Digital outputs
The digital outputs are designed for a voltage level of 12 V and 24 V. The typical connections to the PLC
will not be screened if the modules are arranged carefully and with short cable lengths. As common potential
0V (PIN 4) is used.
All outputs are protected with suppressor diodes and RC-filters against transient overshoots.
Low level: < 4 V
High level: > 10 V
Current: max. 50 mA (with load of 200 Ohm)
Seite 11 von 24

W.E.ST. Elektronik GmbH
Analogue inputs
By use of analogue inputs you have to distinguish between symmetrical and asymmetrical inputs.
All analogue inputs must be screened.
The symmetrical input is carried out as a differential input for voltage signals and can be switched over
per software to bipolar or unipolar signals. Especially by use of high-resolution analogue signals an additional
cable twisted in pairs has to be taken.
The asymmetrical inputs are optimized for the two-pole-conductor techniques (voltages or current signals
as usual in the automobile industry). They can be switched over by software between voltage and
current input. A low-impedance GND connection is required for good signal transmission. In this configuration
the return line is the GND of the power supply. Therefore sensors and the control module should be
combined at a common star point (low impedance) with the GND of the power supply. As common potential
the 0V PIN 11 and optionally PIN 12 are used.
All inputs are protected with suppressor diodes and RC-filter against transient overshoots.
Differential input:
Voltage level: bipolar ±10 V (PIN 9 and PIN 10)
unipolar 0… 10 V (PIN 10 against PIN 9)
input resistance: > 91 kΩ
Asymmetrical inputs:
Voltage level: unipolar 0… 10 V (against PIN 11)
input resistance: 25 kΩ
Current level: unipolar 4… 20 mA (against PIN 11)
input resistance: app. 250 Ω
Analogue outputs
The analogue outputs are carried out as symmetrical differential outputs. Because all power amplifiers
have a differential input (especially valves with integrated electronics), an optimal signal transmission
even over greater distances is possible. All analogue outputs have to be wired with screened cables.
Ideally, twisted pair cables are used. For the signal potential or if both outputs are used as two separate
asymmetrical signals (f. e. for plug amplifiers), PIN 12 as GND potential has to be used. All outputs are
protected with suppressor diodes against transient overshoots.
As differential output:
Voltage level: bipolar ±10 V (PIN 15 and PIN 16)
Output current: max. 10 mA
As asymmetrical outputs:
Voltage level: 2 x unipolar 0… 10 V (PIN 15 or PIN 16 against PIN 12)
Output current: max. 10 mA
Seite 12 von 24

W.E.ST. Elektronik GmbH
As current output:
Voltage level: 1 x unipolar 4… 20 mA (PIN 15 to PIN 12)
max output current: max. 22 mA
max load: 390 ohm
ATTENTION! At the asymmetrical output with the 0 V potential at PIN 12 a minimal
output voltage of approx 0,1 to 0,15 V exists.
Serial interface
The serial interface is chosen for the parametering with a PC or a notebook. A suitable cable of 3,5mm
JISC-6560 plug to 9pol. RS232 (PC compatible) can be bought under RS232-SO.
You can parameterize our modules with each terminal program. However, by use of our application software
WPC-300 you have enlarged functions and therefore it is preferable.
Download: WWW.WEST-ELECTRONICS.COM or WWW.W-E-ST.DE
Features:
• Table orientated parametering
• Saving and loading of the parameter sets
• Process data monitoring
• Oscilloscope for dynamical optimization of the control parameters
• Terminal window for flexible data input
Seite 13 von 24

W.E.ST. Elektronik GmbH
Start-up and commissioning guidelines
1. The module must be mounted and wired with attentions to EMC requirements. A star orientated
ground connection should be used when other power consumers are sharing the same power
supply. Following points have to be taken in account for wiring:
• Signal cable and power cable have to be wired separately.
• Analogue signal cables must be screened.
• Other cables should be screened in case of strong electrical disturbance (power relays,
frequency controlled power driver) or at cable lengths > 3m. With high frequency EMI inexpensive
ferrite elements can be used. In this typical configuration of installation (see
point 2 to 4), no extra step should be taken in consideration.
2. By the arrangement of the electrical cabinet a separation between the power part (and power cables)
and signal part must be taken in consideration. Experience shows us that the area next to
the PLC (24 V area) is suitable.
3. Low impedance between PE “protected earth” and DIN-Rail should be used. Transient interference
voltages at the terminals are discharged via DIN-Rail to the local PE. The screens have to
be connected directly next to the module via PE terminals.
4. The power supply should be carried out voltage regulated (i. e. PWM controlled). The low impedance
of controlled power supplies facilitates improved interference damping. Therefore the signal
resolution will be increased. Switched inductance (relays and solenoids) operating from the same
power supply has to be damped by surge protection elements directly by the inductance.
5. According to the motion diagram, the power amplifier- / valve- / drive combination should drive
out with positive output signal (PIN 15 to PIN 16) and the output voltage of the sensor heightens.
ATTENTION: This output is a differential output. Both outputs may not be
connected with 0V.
Seite 14 von 24

Parameter table
W.E.ST. Elektronik GmbH
Commands Parameter Defaults Units Description
ain:i a b c x i= W|X
a= -10000… 10000
b= -10000… 10000
c= -10000… 10000
x= V|C
a:i x i= A|B
x= 1… 2000
d:i x i= A|B
x= 10… 10000
ctrl x x= lin|sqrt1
|sqrt2
: 10000
: 10000
: 0
: V
:A 100
:B 100
:A 2500
:B 2500
-
-
0,01%
-
ms
ms
0,01%
0,01%
Seite 15 von 24
Analogue output selection. W and X for the inputs and V = voltage,
C = current. With the parameters a, b and c the inputs can be scaled
(output = a / b * (input - c)).
Because of the programming of the x-value (x = C) the corresponding
input will be switched over to current automatically.
Acceleration time depending on direction. A indicates analogue output
15 and B indicates analogue output 16.
Normally A = flow p-A, B-T and B = flow P-B, A-T.
Deceleration stroke depending on direction. The loop gain is calculated
by the deceleration stroke. The shorter the higher. In case of
instabilities longer deceleration stroke will be sufficient.
sqrt1 - Selection of the control function: lin = standard linear P-control,
sqrt1 = progressive time optimized deceleration curve, sqrt2 = sqrt1
with a higher gain in position
velo x x= 1000… 10000 10000 0,01% Internal limitation of the velocity. This limitation is active when command
vs = off.
vs x x= ext|int int - Activates the external velocity limitation with the parameter EXT.
vramp x x= 1… 2000 50 ms Ramp time for velocity input.
vmode x x= on|off off - Activation of the NC-generator. The command position is generated
by a velocity profile (internal or external preset of v). The axis drives
more or less speed controlled.
th x x= 100… 60000 5000 ms Stroke time for 100% velocity and 100% nominal sensor stroke.
hand:i x i= A|B
x= -10000… 10000
min:i x i= A|B
x= 0… 5000
max:i x i= A|B
x= 5000… 10000
:A 3300
:B -3300
:A 0
:B 0
:A 10000
:B 10000
0,01%
0,01%
0,01%
0,01%
0,01%
0,01%
Degree of output signal in manual mode
Deadband compensation of positive overlapped proportional valves.
Good adjustment will increase positioning accuracy.
Maximum output range for adapting control range to maximum flow
range.
trigger x x= 0… 2000 200 0,01% Point to activate the deadband compensation (min). Also useful for
reduced sensitivity in position with control valves.
inpos x x= 2… 2000 200 0,01% Range for the InPos signal (status output).
offset x x= -2000… 2000 0 0,01% The offset will be added to the command value.
pol x x= +|- + - For changing the output polarity. All A and B adjustments depend on
the output polarity. The right polarity should be defined first.
sens x x= on|off on - Activation of the sensor and internal failure monitoring.
save - - - Storing the programmed parameter in E²PROM.
loadback - - - Reloading the parameter from E²PROM in working RAM
din - - - Status of the digital inputs.
w, x, xw, u ,v - - - Actual signals: command value, actual value, process data, control
divergence and reference value.
default - - - Preset values will be set.

Parameter description
AIN (input signal scaling)
W.E.ST. Elektronik GmbH
Commands Parameter Defaults Units
ain:i a b c x i= W|X
a= 0… 10000
b= 0… 10000
c= -10000… 10000
x= V|C
: 1000
: 1000
: 0
: V
Seite 16 von 24
-
-
0,01%
-
With this command each input can be scaled individually. For the scaling function the following linear
equation is taken.
a
y =
⋅ −
b
( x c)
x is the input signal and y is the output signal.
At first the offset (c) will be subtracted (in 0,01% units) from the input signal, then the signal will be multiplied
with factor a / b. a and b should always be positive. With these both factors every floating-point
value can be simulated (for example: 1.345 = 1345 / 1000).
With the x parameter value the internal measuring resistance for the current measuring (0… 20 mA or
4… 20 mA) will be activated (V for voltages input and C for current input).
AIN:xx a b c x
i with voltage (V): AIN:i 1000 1000 0 V
i with current (C): AIN:i 1250 1000 2000 C
Inverted (sensor works from 10 V to 0 V)
AIN:xx a b c x
i with voltage (V): AIN:I -1000 1000 10000 V
A (acceleration time)
Commands Parameter Defaults Units
a:i x i= A|B
x= 0… 2500
:A 100
:B 100
This parameter is set in ms.
The ramp time is separately set for driving out (A) and for driving in (B).
ms
ms

D (deceleration stroke or braking distance)
W.E.ST. Elektronik GmbH
Commands Parameter Defaults Units
d:i x i= A|B
x= 0… 10000
:A 2500
:B 2500
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0,01%
0,01%
This parameter is set in 0,01% units of the maximum length of the sensor.
The braking distance is set dependent from the direction. The controller gain will be calculated by means
of the braking distance. The shorter the braking distance the higher the control gain (see command
CTRL). In case of instabilities a longer braking distance should be set.
CTRL (braking characteristics)
Commands Parameter Defaults Units
ctrl x x= lin|sqrt1
|sqrt2
sqrt1 -
With this parameter, the braking characteristic of the hydraulic axis is controlled. With positive overlapped
proportional valves one of both SQRT braking characteristics should be used. The nonlinear flow curve of
the valves is mostly linearized by the SQRT function.
If zero overlapped proportional valves (control valves) are used, you can choose between LIN and
SQRT1 according to the application. The progressive gain characteristic of SQRT1 has the better positioning
accuracy. According to the application there is maybe a longer braking distance, so that the total
stroke time will be longer.
LIN: Linear braking characteristics (control gain corresponds to: 10000 / d:i).
SQRT1: Root function for the calculation for the braking curve. The control gain goes up quadratic
with a small control error (control gain corresponds to: 30000 / d:i). This characteristic
is preferably used with positive overlapped proportional valves.
SQRT2: Root function for the calculation for the braking curve. The control gain goes up quadratic
with a small control error (control gain corresponds to: 50000 / d:i).
Velocity
CTRL = LIN
Braking stroke
D:A or D:B
Stroke
CTRL = SQRT

VELO (Internal velocity preset)
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Commands Parameter Defaults Units Description
velo x x= 1000… 10000 10000 0,01%
Here the maximum velocity can be limited internally. The limitation function corresponds to the external
velocity preset if VS was parameterized with EXT.
VS (internal or external velocity preset)
Commands Parameter Defaults Units
vs x x= EXT|INT INT
Switch over between internal and external velocity preset.
In case of external velocity preset external voltages at PIN 9 and PIN 10 are used. An input of 10V corresponds
with 100% speed.
VRAMP (ramp time for the external velocity)
Commands Parameter Defaults Units
vramp x x= 1… 2000 50 ms
Here the ramp time for velocity changes will be set.
Operating shocks can be reduced when changing the external velocity.
VMODE (Activation of the NC mode)
Commands Parameter Defaults Units
vmode x x= ON|OFF OFF
With this parameter the NC mode (almost closed loop controlled velocity) will be activated. In OFF state
the stroke depended deceleration is active; the velocity preset limits the output signal.
In ON state the positioning demand value is generated by a profile generator and the axis drives to the
target position with the defined velocity. The stroke time is defined by the parameter th.
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TH (Stroke time for the speed controlled axis)
Commands Parameter Defaults Units
Th x x= 100… 60000 5000 ms
The stroke time is defined for the stroke of 100 %.
It is also defined for 10 V (100 %) velocity and can be reduced by the external speed input.
HAND (Hand speed)
Commands Parameter Defaults Units
hand:i x
i= A|B
x= -10000… 10000
:A 3330
:B -3330
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0,01%
0,01%
With this parameter, the hand speed can be preset. For the corresponding switch input the direction can
be defined by the sign.
The hand speed is also limited by the external velocity preset (MIN evaluation).

MIN (compensation of the dead zone)
MAX (maximum output signal)
TRIGGER (threshold value of MIN)
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Commands Parameter Defaults Units
min:i x
max:i x
trigger x
i= A|B
x= 0… 5000
x= 5000… 10000
x= 0… 2000
-
0
10000
200
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-
0,01%
0,01%
0,01%
With this command, the output signal is adjusted to the valve characteristics. The positioning controllers
have a double-gain characteristic curve instead of a typical overlapped jump. The advantage is a better
and more stabile positioning behaviour. With this compensation, non-linear volume flow characteristic
curves can be adjusted too.
MIN:B
MAX:B
ATTENTION: If there exist also possibilities for adjustments at the valve or at the valve
electronics, it has to be guaranteed, that the adjustment has to be carried out at the
power amplifier or at the positioning module.
If the MIN value is set too high, it influences the minimal velocity, which cannot be adjusted
any longer. In extreme case this causes to an oscillating around the closed loop
controlled position.
Output
two flow gain
characteristics
TRIGGER
standard deadband
compensation
Input
MAX:A
MIN:A

INPOS (in positioning window)
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Commands Parameter Defaults Units
inpos x x= 2… 2000 200 0,01%
This parameter is used in 0,01% units.
The INPOS command defines the window where the INPOS message is indicated. The positioning
process is not influenced by this message. The controller remains active.
In NC-mode this message has to be interpreted alternatively as following error.
OFFSET (zero point adjustment)
Commands Parameter Defaults Units
offset x
x= -2000… 2000 0 0,01%
This parameter is entered in 0,01% units.
The corresponding OFFSET will be added to the control error (demand value - actual value + offset). With
this parameter the zero point failure can be compensated.
POL (output polarity)
Commands Parameter Defaults Units
pol x x= +|- + -
The output polarity of the controller can be switched over.
SENS (sensor monitoring)
Commands Parameter Defaults Units
sens x x= ON|OFF ON -
The sensor monitoring can be activated (with 4… 20 mA sensors).
SAVE (data storing in EEPROM)
Commands Parameter Defaults Units
save - - -
Every parameter change is immediately active but only saved in RAM. For permanent storing in
EEPROM the command SAVE is used to copy the parameter from RAM into EEPROM memory.
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LOADBACK (copy of the EEPROM into the active RAM)
Commands Parameter Defaults Units
loadback - - -
With this command, the data will be written back from EEPROM to RAM. This is helpful when the previous
control parameter (before the last saving) will be reactivated.
DEFAULT (parameter reset)
Commands Parameter Defaults Units
default - - -
Reset of all parameters to the set in factory definition. Data not stored in EEPROM.
PROCESS DATA (monitoring)
Commands Parameter Units
w
Demand value
0,01%
x
Actual value
xw
Control deviation
v
Velocity
u
Actuator signal
The process data can be read out now. They show the actual and command values.
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Appendix: Power stage (PEXT3)
Description of the integrated power stage see: Pext3.PDF
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Remarks
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