Motrona IT251 User manual

Operating Manual
motrona GmbH, Zeppelinstraße 16, DE - 78244 Gottmadingen, Tel. [phone], Fax [phone], [email protected], www.motrona.com
IT251
Level converter, direction signal decoder and programmable impulse divider
Features:
Level conversion from TTL / RS 422 to HTL 10 ... 30 V and vice versa
Programmable divider for error- free and position-true division of
quadrature encoder Signals (A, B, 90°)
Separate marker pulse divider with individual settings
300 kHz of maximum frequency
Push-pull outputs for direct PLC interfacing
18 ... 30 VDC power supply

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Version:
Description:
It25101e/ TJ/ Sep 03/5
HTL input circuit resistors
It25102a/ hk/ Jan07
Brochure format, improved clarification of functions
It2510_2b_oi/ ag/ Sep-15
Design, Technical Specifications and Safety Instructions updated
Legal notices:
All contents included in this manual are protected by the terms of use and copyrights of motrona GmbH. Any reproduction,
modification, usage or publication in other electronic and printed media as well as in the internet requires prior written
authorization by motrona GmbH.
Table of Contents
1. Safety Instructions and Responsibility ......................................................... 3
1.1. General Safety Instructions...................................................................................3
1.2. Use according to the intended purpose ................................................................3
1.3. Installation.............................................................................................................4
1.4. Cleaning, Maintenance and Service Notes...........................................................4
2. Introduction ................................................................................................. 5
3. Block Diagram ............................................................................................. 5
4. Connections and Terminal Assignments ...................................................... 6
5. Basic Switch Settings.................................................................................. 8
6. Setting of the Impulse Division Rate.......................................................... 11
7. Index Pulse Divider (Marker Pulse Z).......................................................... 12
7.1. Unchanged index pulse (bypass).........................................................................12
7.2.Modifications of the index pulse ........................................................................12
7.3. Setting of the division rate of the index divider..................................................13
7.4. Position and width of the index pulse.................................................................13
8. Technical Specifications ............................................................................ 15
9. Dimensions................................................................................................ 16

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1. Safety Instructions and Responsibility
1.1. General Safety Instructions
This operation manual is a significant component of the unit and includes important rules and
hints about the installation, function and usage. Non-observance can result in damage and/or
impairment of the functions to the unit or the machine or even in injury to persons using the
equipment!
Please read the following instructions carefully before operating the device and observe all
safety and warning instructions! Keep the manual for later use.
A pertinent qualification of the respective staff is a fundamental requirement in order to use
these manual. The unit must be installed, connected and put into operation by a qualified
electrician.
Liability exclusion: The manufacturer is not liable for personal injury and/or damage to property
and for consequential damage, due to incorrect handling, installation and operation. Further
claims, due to errors in the operation manual as well as misinterpretations are excluded from
liability.
In addition the manufacturer reserve the right to modify the hardware, software or operation
manual at any time and without prior notice. Therefore, there might be minor differences
between the unit and the descriptions in operation manual.
The raiser respectively positioner is exclusively responsible for the safety of the system and
equipment where the unit will be integrated.
During installation or maintenance all general and also all country- and application-specific safety
rules and standards must be observed.
If the device is used in processes, where a failure or faulty operation could damage the system or
injure persons, appropriate precautions to avoid such consequences must be taken.
1.2. Use according to the intended purpose
The unit is intended exclusively for use in industrial machines, constructions and systems. Non-
conforming usage does not correspond to the provisions and lies within the sole responsibility of
the user. The manufacturer is not liable for damages which has arisen through unsuitable and
improper use.
Please note that device may only be installed in proper form and used in a technically perfect
condition - in accordance to the Technical Specifications (see chapter 8). The device is not
suitable for operation in explosion-proof areas or areas which are excluded by the EN 61010-1
standard.

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1.3. Installation
The device is only allowed to be installed and operated within the permissible temperature range.
Please ensure an adequate ventilation and avoid all direct contact between the device and hot or
aggressive gases and liquids.
Before installation or maintenance, the unit must be disconnected from all voltage-sources.
Further it must be ensured that no danger can arise by touching the disconnected voltage-
sources.
Devices which are supplied by AC-voltages, must be connected exclusively by switches,
respectively circuit-breakers with the low voltage network. The switch or circuit-breaker must be
placed as near as possible to the device and further indicated as separator.
Incoming as well as outgoing wires and wires for extra low voltages (ELV) must be separated
from dangerous electrical cables (SELV circuits) by using a double resp. increased isolation.
All selected wires and isolations must be conform to the provided voltage- and temperature-
ranges. Further all country- and application-specific standards, which are relevant for structure,
form and quality of the wires, must be ensured. Indications about the permissible wire cross-
sections for wiring are described in the Technical Specifications (see chapter 8).
Before first start-up it must be ensured that all connections and wires are firmly seated and
secured in the screw terminals. All (inclusively unused) terminals must be fastened by turning the
relevant screws clockwise up to the stop.
Overvoltages at the connections must be limited to values in accordance to the overvoltage
category II.
For placement, wiring, environmental conditions as well as shielding and earthing/grounding of the
supply lines the general standards of industrial automation industry and the specific shielding
instructions of the manufacturer are valid. Please find all respective hints and rules on
www.motrona.com/download.html -->“[General EMC Rules for Wiring, Screening and Earthing]”.
1.4. Cleaning, Maintenance and Service Notes
To clean the front of the unit please use only a slightly damp (not wet!), soft cloth. For the rear no
cleaning is necessary. For an unscheduled, individual cleaning of the rear the maintenance staff
or assembler is self-responsible.
During normal operation no maintenance is necessary. In case of unexpected problems, failures
or malfunctions the device must be shipped for back to the manufacturer for checking, adjustment
and reparation (if necessary). Unauthorized opening and repairing can have negative effects or
failures to the protection-measures of the unit.

It251_02c_oi_e.doc / Apr-16 Page 5 / 16
2. Introduction
IT 251 has been designed as a universal encoder interface for use with incremental encoder
signals. The unit is suitable to solve the following applications:
Level conversion from TTL / RS422 to HTL and vice-versa
Division of quadrature encoder pulses, with adjustable division rate from 1:1 to 1:4096
Separately programmable division of the marker pulses
Translation from any of the three common standards of indication of the direction to any
other standard (quadrature A/B 90° or A = pulse and B = direction or A = forward impulse
and B = reverse impulse)
All settings occur from the top or bottom side of the unit, by means of four 8-position DIL
switches.
The unit is built into a compact housing with 12 screw terminals and two SUB-D-connectors and
can be mounted to DIN rails
3. Block Diagram
A
B
Z
/A
B
/B
/Z
A
Z
2x 90°
direction
Impulse forw.
Impulse rev.
A
2x 90°
direction
Impulse forw.
Impulse rev.
/A
B
/B
/Z
A
Z
/A
B
/B
/Z
Z
1
7
2
8
3
9
4
5
6
LED “State” (yellow)
Impulse A
LED “On” (green)
Power on

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4. Connections and Terminal Assignments
For frequency input, either the RS 422 inputs (D-SUB) or the 10 … 30 V HTL inputs can be used.
The other inputs, which are not in use, must remain unconnected or must be disabled by
corresponding DIL switch setting.
The outputs provide impulse signals at TTL / RS422 level as well as at a 10 … 30 V HTL level,
and either one or the other or both at a time can be used, whichever is applicable.
Please note that all input and output signals refer to the same common potential (GND) which at
the same time is also the minus potential of the power supply.
RS422 output
(male)
(female)
/A
/B
/Z
A
B
Z
+
Screen*
_
7
8
9
10
11
12
1
2
3
4
5
6
A
B
Z
DIL switch 1
Impulse divider
DIL switch 2
Impulse divider
DIL switch 3
Index divider
DIL switch 4
Configuration
GND
Input
HTL Output
HTL
HTL
Output
Power on
Impulse A
*) This screen terminal allows to connect the metallic housings of the SUB-D-connectors to the
potential applied to terminal 12 (e.g. PE or external GND or else), when the corresponding DIL
switch is on (see settings of DIL 4 switch)
The D-SUB input connector provides an auxiliary output of +5 V / 130 mA for encoder supply.
The HTL inputs provide PNP characteristics and must be switched to +.
Where you use encoders with PNP or push-pull outputs, there will be no problem.
Encoders with NPN outputs (open collector type) will however need an external pull-up resistor
(e.g. 2.7 kOhm). See the schematics of the input circuit for calculation of the resistance.
At any time, the total transmission characteristics of encoder, external components and capacity
of the cable must ensure proper signals at the input terminals of the unit, with respect to the
levels, the shape and the phase displacement A/B.
The output swing on the HTL push- pull outputs corresponds to the input supply voltage applied to
terminals 10 and 11.
The green front LED signals that power is on, and the yellow LED signals the input impulses from
input channel A respectively A, /A.
Power Supply
18 … 30 VDC

It251_02c_oi_e.doc / Apr-16 Page 7 / 16
-
+
Vref =5.5 V
HTL input 2.7 k
6 k
Low < 4.0 V
High > 9.0 V
B/A A +5.5V GND
/N N/B
1 2 3 4 5
986 7
B/AAGND
/NN/B
12345
9 8 67

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5. Basic Switch Settings
Upon commissioning, some basic settings must be done by switch DIL4.
These settings select one of the possible standards for expressing the direction of rotation on
inputs and outputs. Also the potential of the metallic housings of the SUB-D-connectors can be
set, and the inputs can be enabled or disabled (RS422 signals or HTL signals)
Changes of the DIL switch positions will become active
only after the next power-up of the unit!
DIL 3
DIL 4
Fro nt side Back side
Top side
DIL switches DIL3 and DIL4 are located on the top side and switches DIL1 and DIL2 are located on
the bottom side of the unit.

It251_02c_oi_e.doc / Apr-16 Page 9 / 16
Configuration
DIL4
8
7
6
5
4
3
2
1
on
on
A
B
1**
Output direction
standard
on
off
A
B
2
off
on
A
B
3
on
on
1
Input direction
standard
on
off
A
B
2*
off
on
A
B
3*
on
Connects the metallic housing of SUB-D-connector “RS422
Input” to terminal 12
off
Metallic housing of the SUB-D-connector
“RS422 Input” is potential-free
on
Connects the metallic housing of SUB-D-connector “RS422
Output” to terminal 12
off
Metallic housing of the SUB-D-connector
“RS422 Output” is potential-free
on
HTL Inputs disabled
off
HTL Inputs enabled
on
TTL / RS422 Inputs disabled
off
TTL / RS422 Inputs enabled
*) Where your application uses input format 2 or 3 to indicate the direction,
you should ensure that changes of direction occur always while the pulse
lines are low. Otherwise there is a risk of cumulating error pulses at the
output with frequent changes of direction.
**) Also from input signals according to direction standards 2 or 3, the unit
can generate a quadrature output with A/B phase displacement, according to
direction standard 1. However, with the divider set to 1:1, the phase
displacement then is constant in time, i.e. the phase between A and B
corresponds to 90° only at a certain input frequency, and becomes smaller
with lower input frequencies.
This, in general, is not a restriction for proper detection of the direction,
because practically every counter or position controller can clearly interpret

It251_02c_oi_e.doc / Apr-16 Page 10 / 16
this information, even when the phase is barely visible on an oscilloscope.
For this kind of application, please set the A/B delay time by DIL switch 2,
with consideration of your maximum output frequency.
For division rates higher than 1:1, the phase displacement gets more and
more close to a real 90º quadrature signal, independent of the input
frequency.
A/B time displacement when converting
direction standard 2 or 3 to quadrature standard
A/B Time Displacement
DIL2
8
7
on
on
T = 0,4 µs
on
off
T = 1,2 µs
off
on
T = 4,4 µs
off
off
T = 10,0 µs

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6. Setting of the Impulse Division Rate
The incremental division rate for the A/B input pulses can be set by means of switch DIL1 and by
positions 1 –4 of switch DIL2.
The marker pulse Z uses a separate divider and marker division is described later.
The switch positions use a binary code like shown in the subsequent list. For technical reasons, a
switch in ON position means logical “0” and a switch in OFF position means logical “1”.
Set all switch positions to a binary code that corresponds to the desired division rate –1
Impulse Divider [A / B]
DIL2
DIL1
on = log.0, off = log.1
Binary value
4
3
2
1
8
7
6
5
4
3
2
1
2048
1024
512
256
128
64
32
16
8
4
2
1
on
on
on
on
on
on
on
on
on
on
on
on
(0) = Division 1 : 1
on
on
on
on
on
on
on
on
on
on
on
off
(1) = Division 1 : 2
on
on
on
on
on
on
on
on
on
on
off
on
(2) = Division 1 : 3
on
on
on
on
on
on
on
on
on
on
off
off
(3) = Division1 : 4
on
on
on
on
on
on
on
on
on
off
on
on
(4) = Division 1 : 5
on
on
on
on
on
on
on
on
on
off
on
off
(5) = Division 1 : 6
on
on
on
on
on
on
on
on
on
off
off
on
(6) = Division 1 : 7
on
on
on
on
on
on
on
on
on
off
off
off
(7) = Division 1 : 8
...etc.
on
on
on
on
on
on
on
off
on
on
on
on
1 : 17
on
on
on
on
on
on
off
on
on
on
on
on
1 : 33
on
on
on
on
on
off
on
on
on
on
on
on
1 : 65
on
on
on
on
off
on
on
on
on
on
on
on
1 : 129
on
on
on
off
on
on
on
on
on
on
on
on
1 : 257
on
on
off
on
on
on
on
on
on
on
on
on
1 : 513
on
off
on
on
on
on
on
on
on
on
on
on
1 : 1025
off
on
on
on
on
on
on
on
on
on
on
on
1 : 2049
...etc.
off
off
off
off
off
off
off
off
off
on
off
off
1 : 4092
off
off
off
off
off
off
off
off
off
off
on
on
1 : 4093
off
off
off
off
off
off
off
off
off
off
on
off
1 : 4094
off
off
off
off
off
off
off
off
off
off
off
on
1 : 4095
off
off
off
off
off
off
off
off
off
off
off
off
1 : 4096

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7. Index Pulse Divider (Marker Pulse Z)
7.1. Unchanged index pulse (bypass)
When you like to just bypass the index pulse from the input to the output (without any changes of
frequency, position and pulse width), please use the following DIL switch settings:
DIL3
DIL2
8
7
6
5
4
3
2
1
6
5
on
on
on
on
on
on
on
on
off
off
In this case you can ignore all further information given in this chapter.
7.2. Modifications of the index pulse
The programmable index divider allows modifications of the pulse distance, the pulse width and
the pulse position.
As a precondition for use of the subsequent functions,
the input index pulse needs to have a
minimum width of one fourth of the period and a
maximum width of one half of the period of the
input frequency
Switch DIL3 allows setting of the division rate between input and output.
Positions 5 and 6 of switch DIL2 allow modification of width and position of the output pulse.
Min.
Max.

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7.3. Setting of the division rate of the index divider
These settings use the same rules and codes as shown with the main divider (see section 6)
Index Divider [Z]
DIL3
on = log.0, off = log.1
Binary value
8
7
6
5
4
3
2
1
128
64
32
16
8
4
2
1
on
on
on
on
on
on
on
on
1 : 1
on
on
on
on
on
on
on
off
1 : 2
on
on
on
on
on
on
off
on
1 : 3
on
on
on
on
on
on
off
off
1 : 4
off
off
off
off
off
off
on
on
1 : 253
off
off
off
off
off
off
on
off
1 : 254
off
off
off
off
off
off
off
on
1 : 255
off
off
off
off
off
off
off
off
1 : 256
7.4. Position and width of the index pulse
For illustration of the functions, the drawings of this chapter assume that the main impulse
divider of the A/B input pulses would be set to 8. The index pulse will appear at the output
according to the division rate set (see section 7.3 above).
DIL2
Small index pulse (1/4 of the input period time)
6
5
off
off
The pulse width on the output is 1/4 of one period on the input side

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DIL2
Enlarged index pulse (one full encoder revolution)
6
5
off
on
The pulse width of the enlarged output index pulse corresponds to the distance
between two input index pulses (with index divider > 1 only).
DIL2
Index pulse width adapted to output frequency (1/4 output period)
(only applicable with quadrature input A/B, 90°)
6
5
on
off*)
The pulse width corresponds to 1/4 of one period of the output frequency
on
on**)
This mode of index treatment requires divider settings of the A/B impulse divider
and the index divider that ensure a clear assignment of the output index pulse to
the A/B output frequency, with no cumulating remainders. Where the signal
division does not come out even, jumps of the output index pulse position will
occur.
Example: With use of a 1000 ppr encoder we would set the A/B impulse divider to
3 and the index divider to 2. As a result the index output pulse should appear after
every 666.6….. input pulses, what physically is impossible without jumps.
*) Pulse width = 1/4 output period, even with index divider set to 1:1
**) Divider setting 1:1 will bypass the input index pulse to the output

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8. Technical Specifications
Power supply:
Input voltage:
Protection circuit:
Ripple:
Consumption:
(unloaded encoder supply)
Connections:
18 … 30 VDC
reverse polarity protection
≤10 % at 24 VDC
approx. 250 mA (at 18 V)
approx. 150 mA (at 30 V)
screw terminal, 1.5 mm² / AWG 16
Encoder supply:
Output voltage:
Output current:
Connections:
+ 5.5 VDC / +/- 5 %
max. 130 mA
male 9-pin SUB-D connector
Incremental input:
Signal levels:
HTL internal resistance
Channels:
Frequency:
Connections:
TTL / RS422, differential voltage > 1 V
HTL, LOW: 0 … 4 V / HIGH: 10 … 30 V
Ri ≈4.7 kOhm
A, B, Z (HTL, asymmetrical)
A, /A, B, /B, Z, /Z (TTL / RS422 symmetrical)
300 kHz
screw terminal, 1.5 mm² / AWG 16 (HTL) or
female 9-pin SUB-D connector (TTL / RS422)
Incremental output:
Signal levels:
Channels:
Output current:
Connections:
17 … 29 V at HTL (depends on power supply voltage)
5 V at TTL / RS422
A, B, Z (HTL, asymmetrical)
A, /A, B, /B, Z, /Z (TTL / RS422 symmetrical)
max. 20 mA / push-pull
screw terminal, 1.5 mm² / AWG 16 (HTL) and
male 9-pin SUB-D connector (TTL / RS422)
Housing:
Material:
Mounting:
Dimensions:
Protection class:
Weight:
plastic
35 mm top hat rail (according to EN 60715)
w x h x d = 40 x 79 x 91 mm
resp. 1.5748 x 3.1102 x 3.5827 inch
IP20
approx. 200 g
Ambient temperature:
Operation:
Storage:
0 °C … +45 °C / +32 … +113 °F (not condensing)
-25 °C … +70 °C / -13 … +158 °F (not condensing)
Failure rate:
MTBF in years:
55.4 a (long-term usage at 60 °C / 140 °F )
Conformity & standards:
EMC 2004/108/EC:
Guideline 2011/65/EU:
EN 61000-6-2, EN 61000-6-3, EN 61000-6-4
RoHS-conform

It251_02c_oi_e.doc / Apr-16 Page 16 / 16
9. Dimensions
40 mm (1.575’’)
79 mm (3.110’’)
74 mm (2.193’’)
91mm (3.583’’)
Front view Side view