Motrona SI 251 User manual

control – motion – interface
SI25101B_e.DOC / Mrz-08 Page 1 / 16
SI 251
Sine/Cosine Interpolator with
Adjustable Multiplication Rate,
for Use with Sine/Cosine Encoder Systems
•Converts sinus wave inputs with 1 Vss standard level into incremental quadrature
output signals
•Outputs A, /A, B, /B, Z, /Z (RS422 / TTL) and A, B, Z (80 – 30 V HTL)
•Adjustable multiplier for interpolation rates from 1:5 to 1:50
•Adjustable divider 1:1 – 1:128 to reduce the output frequency
•Sinus-input frequency 0 - 400 kHz
•Quadrature output frequency up to 4 MHz
•Adjustable glitch filter
•Power supply 18 – 30 VDC
Operating Instructions
ELEKTRO-TRADING sp. z o.o
Tel. [phone]
Tel/Fax [phone]
E- ail [email protected]
http://www.elektro-trading.com.pl

SI25101B_e.DOC / Mrz-08 Page 2 / 16
Safety Instructions
•This manual is an essential part of the unit and contains important hints about
function, correct handling and commissioning. Non-observance can result in
damage to the unit or the machine or even in injury to persons using the
equipment!
•The unit must only be installed, connected and activated by a qualified electrician
•It is a must to observe all general and also all country-specific and application-
specific safety standards
•When this unit is used with applications where failure or maloperation could cause
damage to a machine or hazard to the operating staff, it is indispensable to meet
effective precautions in order to avoid such consequences
•Regarding installation, wiring, environmental conditions, screening of cables and
earthing, you must follow the general standards of industrial automation industry
•- Errors and omissions excepted –
Version: Description:
SI25101a/ AF/ Nov. 04 Original
SI25101b/ AF/HK/ Feb.05 Corrections with connectors male/female, DIL2 settings and
miscellaneous small bugs

SI25101B_e.DOC / Mrz-08 Page 3 / 16
Table of Contents
1. Introduction....................................................................................................4
2. Block Diagram................................................................................................5
3. Connections ...................................................................................................6
4. Pin assignment of SUB-D-connectors ............................................................8
4.1. Sine/Cosine inputs ................................................................................................8
4.2. RS 422 impulse output ..........................................................................................9
5. Switch settings ............................................................................................10
6. Frequency Divider and Error Signals ............................................................ 13
7. Delays ..........................................................................................................14
8. Miscellaneous Hints ....................................................................................14
9. Dimensions .................................................................................................. 15
10. Technical Data .............................................................................................16

SI25101B_e.DOC / Mrz-08 Page 4 / 16
1. Introduction
SI251 represents an encoder interface unit, designed to convert output signals of so-called
“sine-cosine-encoders” and similar measuring systems into incremental quadrature impulse
signals.
Under consideration of an adjustable multiplier the unit interpolates a corresponding number of
impulses from every sine wave. An additional programmable divider provides division of the
impulses if applicable, before they appear at the output. Impulses are available with TTL/RS422
standard (A, /A, B, /B, Z, /Z) and with HTL standard (A, B, Z, 18-30V) at the same time.
SI251 also possesses a selectable glitch filter to minimize interferences on the signal lines. The
maximum sine input frequency is 400 kHz. The interpolation rate can be set in a range from 5 to
50, i.e. the unit can generate up to 50 pulses from one sine period
The maximum output frequency is 4 MHz with use of the RS422 output, and approx. 100 kHz
when the HTL output is used. Where applicable, the output frequency can be reduced by a
selectable divider 1:1 – 1:128.
Independent of the selected interpolation rate, an interpolation time can be set in order to limit
the output frequency to a desired maximum value.
The unit provides auxiliary output voltages of 5.2 volts and approx. 20 volts, all short-circuit-
proofed, for power supply of the sine/cosine encoder.
Errors will be signaled by a LED and at the same time by a digital control output. Errors can be
reset by means of a pushbutton on the unit, or by a remote reset signal.
All settings are done by means of two DIL switches which are accessible from the top site and
the bottom site of the housing.
The mechanical construction provides a compact housing for rail mounting, with
12 screw terminals and two Sub-D-connectors

SI25101B_e.DOC / Mrz-08 Page 5 / 16
2. Block Diagram
/
A ,/B, /Z, A, B, Z
SIN-
COS+
COS-
REF-
SIN+
REF+
3
2
8
Vdd = 20 V / 150 mA
Vcc = 5.2V / 150 mA
1
Encoder Supply
A10
11
9
12
B
Z
Jumper
5
6
GND
+
Power +
-
/A
B
/B
/Z
A
Z

SI25101B_e.DOC / Mrz-08 Page 6 / 16
3. Connections
The unit provides a 9-pin Sub-D connector (female on the unit site) for connection of the
sine/cosine sensor. For easy power supply of the encoder, an external jumper allows to switch
an auxiliary voltage of either 5.2 volts or approx. 20 volts to the same connector. Also the mean
voltage is available on the connector pins, allowing also the use of sensors with non-
differential sinus output.
The incremental output impulses are available with RS422 standard and HTL standard (push-
pull) at the same time, and one output of both or both outputs at a time may be used, quite
according to the application.
All inputs and outputs as well as the power supply refer to the same
reference potential (GND)!
In case of errors the Error Output switches to HIGH. At the same time the yellow front LED will
be lit.
To release an Error state, a HIGH signal must be applied to the “Error Release” input (PNP, HTL,
a positive signal of 10-30 volts will release the error). Errors may be cleared also by pushing the
small button on the top site of the unit.
The unit operates with a 18 – 30 volts DC power applied to terminals 5 (+) and 6 (-)

SI25101B_e.DOC / Mrz-08 Page 7 / 16
male
female
Test
Error Out
Error release
18-30V GND
A(HTL)
Encoder supply
5.2V
VDD
DIL-switch 1 iImpulse divider)
Pushbutton and DIL switch 2 (Configuration)
B(HTL)
Z(HTL)
GND
LED’s
At any time, the over-all transmission characteristics of encoder, external components and
capacity of cable must ensure proper signals at the input of the unit, with respect to levels,
shape and phase displacement A/B.
The output swing of the HTL push- pull outputs corresponds to the input supply voltage on
terminals 5 and 6.

SI25101B_e.DOC / Mrz-08 Page 8 / 16
4. Pin assignment of SUB-D-connectors
4.1. Sine/Cosine inputs
Standard encoders with differential outputs can be connected directly to the corresponding pins
SIN+, SIN-, COS+, COS-, REF+, REF-.
Where longer cables must be used, terminating resistors between the non-inverted and the
inverted signal of each channel may be of advantage.
COS+ SIN- SIN+
GND
REF- REF+ COS-
12 3 4 5
9867
Vm
Encoder supply from terminal 1
SIN+
SIN-
COS+
COS-
REF+
REF-
3
2
1
9
7
6
GND
GND
With sensors using single-ended outputs, the sensor signals SIN, COS and REF are connected
to the corresponding input pins. The inverted inputs of the unit are tied to either the mean
voltage output Vm(pin 8) of the unit, or to a corresponding voltage reference of the sensor itself
SIN+
COS+
REF+
3
2
1
9
7
6
GND
GND
Vm1
Vm2

SI25101B_e.DOC / Mrz-08 Page 9 / 16
When the reference signals REF+ and REF- are not used or not available, the related inputs of
the converter must be tied to a defined potential.
When you connect the REF- pin to Vmwith the REF+ pin open, the unit will generate a Z
impulse with every sine period.
When you connect the REF+ pin to Vmwith the REF- pin open, the unit will not generate a Z
impulse.
The sine-cosine signals on the input site are highly sensitive analogue
signals! Therefore it is mandatory to use proper screening. Use of cables
with pair wise twisted leads is highly recommended. The cable length should
not exceed 5 meters if possible.
With critical applications, a terminating impedance (approx. 470 ohms, and
where required a capacitor of 680 pF to 4.7 nF) connected between the
differential inputs may be helpful.
4.2. RS 422 impulse output
B/AA
GND
/ZZ/B
12345
98 67

SI25101B_e.DOC / Mrz-08 Page 10 / 16
5. Switch settings
Switch DIL1 allows to set the filter and to choose the interpolation rate and interpolation time.
Switch DIL2 selects a programmable divider and allows to set the unit to test mode
Changes of the DIL switch positions will become active only after the next
power-up of the unit!
DIL1: ( 0 = OFF, 1 = ON ) Interpolation and Filtering
8 7 6 5 4 3 2 1
1 1 Minimum Filter
1 0 Filter 10kHz
0 1 Filter 100 kHz
1 Glitch-Filter OFF
0 Glitch-Filter ON
Filtering
1 1 1 40
1 1 0 20
1 0 1 10
1 0 0 5
0 1 1 50
0 1 0 25
0 0 1 12,5
0 0 0 6,25
Interpolation rate
1 1 25ns
1 0 100ns
0 1 400ns
0 0 1600ns
Interpolation time

SI25101B_e.DOC / Mrz-08 Page 11 / 16
Hints for settings of DIL switch 1:
•Under proper electrical conditions there is no imperative need to use the
filtering functions offered in the table above. When you set your
interpolation factor with use of the filter settings highlighted in the table,
there will be no further restrictions with the operating range of the unit.
•se of the filtering functions will eliminate noise on the signal lines, but at
the same time result in some limitations and restrictions of the operating
range. The sine input frequency must not exceed the selected filter
frequency. Where you decide to use the 100 kHz filter, the unit will not
respond to frequencies higher than 100 kHz.
•Distortions of the input signal result in fluctuation of the output frequency.
•Use of the glitch filter results in increased interpolation times at standstill
or with low input frequencies, therefore reduces noise and jitter of the
output signal by a few increments up and down in standstill. However,
when the glitch filter is switched on, fast changes of the speed can result
in temporary proportional errors between input frequency and output
frequency during acceleration
The subsequent table shows the limits of input and output frequencies with respect to the DIL
switch settings:
Interpolation rate Interpolation time Maximum output
frequency
Maximum input
frequency
25 ns 2 MHz 400 kHz
100 ns 2 MHz 400 kHz
400 ns 625 kHz 125 kHz
x5
1600 ns 156.25 kHz 31.25 kHz
25 ns 2,5 MHz 400 kHz
100 ns 2,5 MHz 400 kHz
400 ns 625 kHz 100 kHz
x6,25
1600 ns 156.25 kHz 25 kHz
25 ns 4 MHz 400 kHz
100 ns 2,5 MHz 250 kHz
400 ns 625 kHz 62.5 kHz
x10
1600 ns 156.25 kHz 15.625 kHz

SI25101B_e.DOC / Mrz-08 Page 12 / 16
Interpolation rate Interpolation time Maximum output
frequency
Maximum input
frequency
25 ns 4 MHz 320 kHz
100 ns 2.5 MHz 200 kHz
400 ns 625 kHz 50 kHz
x12,5
1600 ns 156.25 kHz 12.5 kHz
25 ns 4 MHz 200 kHz
100 ns 2.5 MHz 125 kHz
400 ns 625 kHz 31.25 kHz
x20
1600 ns 156.25 kHz 7.8125 kHz
25 ns 4 MHz 160 kHz
100 ns 2.5 MHz 100 kHz
400 ns 625 kHz 25 kHz
x25
1600 ns 156.25 kHz 6.25 kHz
25 ns 4 MHz 100 kHz
100 ns 2.5 MHz 62.5 kHz
400 ns 625 kHz 15.625 kHz
x40
1600 ns 156.25 kHz 3.90625 kHz
25 ns 4 MHz 80 kHz
100 ns 2.5 MHz 50 kHz
400 ns 625 kHz 12.5 kHz
x50
1600 ns 156.25 kHz 3.125 kH

SI25101B_e.DOC / Mrz-08 Page 13 / 16
6. Frequency Divider and Error Signals
The programmable frequency divider provides decrease of the output frequency by an
adjustable division rate between 1:1 and 1: 128.
The following errors are detected and indicated by the yellow LED and the Error output:
•Wire break with one of the signals SIN+, SIN-, COS+ or COS-
•Too low amplitude on one of above signal lines
•The input frequency exceeds it’s maximum level, the output frequency is unable to
follow
•The signals REF+ and REF- are not subject of the error check procedure. Depending on
the settings on the DIL2 switch, error signals remain active until remote
acknowledgement, or reset automatically upon elimination of the error.
•In case of an error the proper function of the unit is not ensured and a loss of encoder
pulses can occur.
DIL2: ( 0 = OFF, 1 = ON ) Divider and testing functions
8 7 6 5 4 3 2 1
1 1 1 1 1 1 1 : 2
1 1 1 1 1 0 1 : 4
1 1 1 1 0 1 1 : 6
1 1 1 1 0 0 1 : 8
1 1 1 0 1 1 1 : 10
1 1 1 0 1 0 1 : 12
1 1 1 0 0 1 1 : 14
1 1 1 0 0 0 1 : 16
1 1 0 1 1 1 1 : 18
- - - - - - - - - - - - - - - - - - - - - -
0 0 0 0 0 0 1 : 128
Division rate
1 Automatic error reset
0 Static error message Error LED and output
0 Divider switched on
1 Divider switched off
Divider

SI25101B_e.DOC / Mrz-08 Page 14 / 16
7. Delays
There is a delay time between the analogue input signals and the incremental output signals,
which is typically 3 μsec. when the divider is switched off.
Use of the divider function will extend the delay time correspondingly.
Since the delay time is constant, there will be a phase displacement between input and output,
depending on the actual frequency.
8. Miscellaneous Hints
•The unit will reach full accuracy only after a transient period of approximately 20 full
sine cycles at the input. Before that, the input frequency should not exceed about 50 %
of the normal maximum frequency
•The application of digital interpolation procedures requires use of quantization steps,
which can cause a certain dither of the output signal.
•The quality of the output signal depends essentially on the input signals. Therefore
maximum elaborateness is recommended with screening, running of cables and cable
length.
•SI251 does not possess a potential separation, i.e. the unit GND is at the same time
also GND of the sensor. Therefore it is important to ensure clear conditions with
earthing and to prevent earth loops and balance currents flowing through the unit.
Where unrulable potential situations should come up, it is recommended to use a fully
separate power supply for the SI 251 unit

SI25101B_e.DOC / Mrz-08 Page 15 / 16
9. Dimensions
40 mm (1.575’’)
79
mm
(3.110’’)
74 mm (2.193’’)
91mm (3.583’’)
Front view Side view

SI25101B_e.DOC / Mrz-08 Page 16 / 16
10. Technical Data
Power Supply (with no external load) : Vdd = 18 V DC (0.15 A) – 30 V DC (0.09 A)
Aux. Voltage Output 1 : 5.2 V / max. 150 mA
Aux. Voltage Output 2 : Vdd – 4V / max. 150 mA
Input frequency : max. 400 kHz
Amplitude Sine/Cosine Inputs : min. 0.8 Vpp – max.1.2 Vpp
DC Offset Sin/Cos Inputs : min.1.8V – max. 3.1V
Differential Ref Input: High : 130mV ; Low : 40mV
Output voltage HTL : Vdd – 4V
Output voltage HTL Error : Vdd – 4V
Output current HTL : max. 40 mA (push-pull)
Input level HTL : LOW < 4 V, HIGH > 10 V
Input resistance HTL : approx. 10 kΩ
Operating temperature range : 0...+45 °C / 32...110 °F
Weight : approx. 200 g
Conformity and Standards : EMC 89/336/EEC : EN 61000-6-2
EN 61000-6-3
LV73/23/EEC : EN 61010-1