Isel MD24 User manual

isel®Germany AG D-36124 Eichenzell Bürgermeister-Ebert-Str. 40 +49/(0)6659/981-700 +49/(0)6659/981-776
Item-no. 970317 BE001
Last update: 01/2010
MD24 / MD28
Microstepping Driver
odul
Instruction Manual
Hardware Description

The information, technical data and dimensions contained in this manual
correspond to the best available technology at the time of publication.
Nevertheless existing misprints and errors cannot be excluded. We are always
grateful for improvement suggestions and error hints.
We point out to the fact that software and hardware names of the respective
companies that are used in our prints are generally subject to trademark or brand
or patent protection.
All rights reserved. No part of our prints may either be reproduced in any form
(print, photography or another procedure) or processed, copied or published by
using electronic systems without written permission of isel®.
Manufacturer: isel®Germany AG
Buergermeister-Ebert-Straße 40
D-36124 Eichenzell
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Web: http://www.isel.com

1
Table of Content
1Introduction ......................................................................................................... 1
2Safety Instructions.............................................................................................. 2
3Technische Daten................................................................................................ 3
4Dimensions.......................................................................................................... 3
5Pin Assignment................................................................................................... 4
5.1 P1 - Control-Signals.................................................................................... 4
5.2 P2 - Motor / Power-supply........................................................................... 4
6Jumpers ............................................................................................................... 5
7Control Signal Connector (P1) Interface ........................................................... 6
8Connecting the Motor (P2) ................................................................................. 7
8.1 Connections to 4-lead Motors ...................................................................... 7
8.2 Connections to 6-lead Motors ...................................................................... 7
8.2.1 Half Coil Configurations 7
8.2.2 Full Coil Configurations 8
8.3 Connections to 8-lead Motors ...................................................................... 8
8.3.1 Series Connections 8
8.3.2 Parallel Connections 9
9Power Supply Selection...................................................................................... 9
9.1 Regulated or Unregulated Power Supply..................................................... 9
9.2 Multiple Drivers........................................................................................... 10
10 Selecting Microstep Resolution and Driver Output Current.......................... 10
10.1 Microstep Resolution Selection.................................................................. 10
10.1.1 MD24 10
10.1.2 MD28 11
10.2 Current Settings ......................................................................................... 11
10.2.1 MD24 11
10.2.2 MD28 12
10.3 Standstill Current Setting............................................................................ 12
11 Wiring Notes...................................................................................................... 12
12 Typical Connection........................................................................................... 13

2
13 Sequence Chart of Control Signals................................................................. 13
14 Protection Functions ........................................................................................ 14
15 Problem Symptoms and Possible Causes...................................................... 15

MD24 / MD28 –Hardware Description
1
1 Introduction
The MD24 / MD28 are economical microstepping driver based on patented technology. It
is suitable for driving 2-phase and 4-phase hybrid stepping motors. By using the
advanced bipolar-current chopping technique, it can output more speed and torque from
the same motor, compared with traditional drivers, such as L/R drivers. Its 3-state current
control technology allows coil currents to be well controlled and with relatively small
current ripple, therefore less motor heating is achieved.
Features:
- Low cost and good high-speed torque
- Optically isolated input signals
- Pulse frequency up to 300 KHz
- Automatic idle-current reduction
- 3-state current control technology
- High resolution Microstepping
- Suitable for 2-phase and 4-phas motors
- DIP-Switch setting
- Over-voltage and short-circuit protection
Small size
Suitable for a wide range of stepping motors from Nema size 17 to 34. It can be used in
various kinds of machines, such as X-Y tables, labeling machines, laser cutters, engraving
machines, pick-place devices, and so on. Particularly adapt to the applications desired with
low vibration, high speed and high precision.

MD24 / MD28 –Hardware Description
2
2 Safety Instructions
The MD24 / MD28 modules are designed according to the current state of the art
and the accepted safety-relevant rules.
The devices may only be actuated in perfect technical condition. Failures are to be
eliminated immediately. Children and persons that are not instructed may not put the
device into operation.
The equipment may only be used for the intended purpose.
All work is to be accomplished exclusively by authorized technical personnel and
with consideration of the regulations of the electrical industry as well as the rules for
the prevention of accidents.
Assembly and employment of the equipment is to be accomplished according to the
standards of the declaration of conformity. The regulations and limit values kept by
the manufacturer do not protect in case of inappropriate use of the equipment.
The equipment may not be exposed to high air humidity and high vibrations
(see technical data).
Keep this operating instructions in a safe place and commit each user
to its observance!
Non-observance of this instruction manual can result in damages to property,
heavy bodily injuries and death.

MD24 / MD28 –Hardware Description
3
3 Technische Daten
MD 24
MD 28
Min.
Typ.
Max.
Min.
Typ.
Max.
Output current [A]
1
-
4,2
2,8
-
7,8
Supply voltage [V]
20
36
50
24
68
80
Logic signal current [mA]
7
10
16
7
10
16
Pulse input frequency [KHz]
0
-
300
0
-
300
Isolation resistance [MΩ]
500
-
-
500
-
-
Cooling
Natural Cooling or Forced cooling
Environment
Avoid dust, oil fog and corrosive gases
Ambient Temperature
0°C –50°C
Humidity
40% RH –90% RH
Operating Temperature
Max. 70°C
Vibration
Max. 5,9m/s2
Storage Temperature
-20°C - 65°C
Weight
Ca. 280 Gramm
Ca. 440 Gramm
Dimensions
118 x 75,5 x 33mm
119 x 97 x 48mm
4 Dimensions
MD24 MD28
Draufsicht Seitenansicht
(All units:mm)

MD24 / MD28 –Hardware Description
4
5 Pin Assignment
5.1 P1 - Control-Signals
Phoenix 6-pin.
Pin
Signal
Description
1
PUL+(+5V)
Pulse signal: In single pulse (pulse/direction) mode, this input represents
pulse signal, effective for each rising or falling edge (set by inside jumper
J1); 4-5V when PUL-HIGH, 0-0.5V when PUL-LOW. In double pulse mode
(pulse/pulse) , this input represents clockwise (CW) pulse, effective for high
level or low level (set by inside jumper J1). For reliable response, pulse
width should be longer than 1.5µs. Series connect resistors for
current-limiting when +12V or +24V used.
2
PUL-(PUL)
3
DIR+(+5V)
DIR signal: In single-pulse mode, this signal has low/high voltage levels,
representing two directions of motor rotation; in double-pulse mode (set by
inside jumper J2), this signal is counter-clock (CCW) pulse, effective for
high level or low level (set by inside jumper J1). For reliable motion
response, DIR signal should be ahead of PUL signal by 5µs at least. 4-5V
when DIR-HIGH, 0-0.5V when DIR-LOW.
4
DIR-(DIR)
5
ENA+(+5V)
Enable signal: This signal is used for enabling/disabling the driver. High
level (NPN control signal, PNP and Differential control signals are on the
contrary, namely Low level for enabling.) for enabling the driver and low
level for disabling the driver.
Usually left UNCONNECTED (ENABLED)
6
ENA-(ENA)
5.2 P2 - Motor / Power-supply
Phoenix 6-pin.
Pin
Signal
Description
1
GND
DC power ground
2
+V
DC power supply (see techn. data)
3
A+
Motor-Phase A
4
A-
5
B+
Motor-Phase B
6
B-

MD24 / MD28 –Hardware Description
5
6 Jumpers
There are two jumpers J1 and J2 inside the MD24 / MD28 specifically for the purpose of
selecting effective pulse edge or effective level and control signal mode, as shown in
figure 2. Default setting is PUL/DIR mode and upward-rising edge effective.
PUL/DIR mode and effective at upward-rising edge PUL/DIR mode and effective at downward-falling edge
CW/CCW mode and effective CW/CCW mode and effective
at high level (The fixed level) at low level (The fixed level)

MD24 / MD28 –Hardware Description
6
7 Control Signal Connector (P1) Interface
The MD24 / MD28 can accept differential and single-ended inputs (including open-collector and
PNP output). The MD24 / MD28 has 3 optically isolated logic inputs which are located on
connector P1 to accept line driver control signals. These inputs are isolated to minimize or
eliminate electrical noises coupled onto the drive control signals. Recommend use line driver
control signals to increase noise immunity of the driver in interference environments. In the
following figures, connections to open-collector and PNP signals are illustrated.
a) Common-anode
b) Common-cathode

MD24 / MD28 –Hardware Description
7
8 Connecting the Motor (P2)
The ME542 driver can drive any 2-pahse and 4-pahse hybrid stepping motors.
8.1 Connections to 4-lead Motors
4 lead motors are the least flexible but easiest to wire. Speed and torque will depend on
winding inductance. In setting the driver output current, multiply the specified phase
current by 1.4 to determine the peak output current.
4-lead Motor Connections
8.2 Connections to 6-lead Motors
Like 8 lead stepping motors, 6 lead motors have two configurations available for high
speed or high torque operation. The higher speed configuration, or half coil, is so
described because it uses one half of the motor’s inductor windings. The higher torque
configuration, or full coil, uses the full windings of the phases.
8.2.1 Half Coil Configurations
As previously stated, the half coil configuration uses 50% of the motor phase windings.
This gives lower inductance, hence, lower torque output. Like the parallel connection of 8
lead motor, the torque output will be more stable at higher speeds. This configuration is
also referred to as half chopper. In setting the driver output current multiply the specified
per phase (or unipolar) current rating by 1.4 to determine the peak output current.
6-lead motor half coil (higher speed) connections

MD24 / MD28 –Hardware Description
8
8.2.2 Full Coil Configurations
The full coil configuration on a six lead motor should be used in applications where higher
torque at lower speeds is desired. This configuration is also referred to as full copper. In
full coil mode, the motors should be run at only 70% of their rated current to prevent
overheating.
6-lead motor half coil (higher speed) connections
8.3 Connections to 8-lead Motors
8 lead motors offer a high degree of flexibility to the system designer in that they may be
connected in series or parallel, thus satisfying a wide range of applications.
8.3.1 Series Connections
A series motor configuration would typically be used in applications where a higher torque
at lower speeds is required. Because this configuration has the most inductance, the
performance will start to degrade at higher speeds. In series mode, the motors should
also be run at only 70% of their rated current to prevent overheating.
8-lead motor series connections

MD24 / MD28 –Hardware Description
9
8.3.2 Parallel Connections
An 8 lead motor in a parallel configuration offers a more stable, but lower torque at lower
speeds. But because of the lower inductance, there will be higher torque at higher
speeds. Multiply the per phase (or unipolar) current rating by 1.96, or the bipolar current
rating by 1.4, to determine the peak output current.
8-lead motor parallel connections
9 Power Supply Selection
The MD24 / MD28 can match medium and small size stepping motors (from Nema size
17 to 34) made by any motor manufactures around the world. To achieve good driving
performances, it is important to select supply voltage and output current properly.
Generally speaking, supply voltage determines the high speed performance of the motor,
while output current determines the output torque of the driven motor (particularly at lower
speed). Higher supply voltage will allow higher motor speed to be achieved, at the price of
more noise and heating. If the motion speed requirement is low, it’s better to use lower
supply voltage to decrease noise, heating and improve reliability.
9.1 Regulated or Unregulated Power Supply
Both regulated and unregulated power supplies can be used to supply the driver.
However, unregulated power supplies are preferred due to their ability to withstand
current surge. If regulated power supplies (such as most switching supplies.) are indeed
used, it is important to have large current output rating to avoid problems like current
clamp, for example using 4A supply for 3A motor-driver operation. On the other hand, if
unregulated supply is used, one may use a power supply of lower current rating than that
of motor (typically 50% - 70% of motor current). The reason is that the driver draws
current from the power supply capacitor of the unregulated supply only during the ON
duration of the PWM cycle, but not during the OFF duration. Therefore, the average
current withdrawn from power supply is considerably less than motor current. For
example, two 3A motors can be well supplied by one power supply of 4A rating.

MD24 / MD28 –Hardware Description
10
9.2 Multiple Drivers
It is recommended to have multiple drivers to share one power supply to reduce cost, if
the supply has enough capacity. To avoid cross interference, DO NOT daisy-chain the
power supply input pins of the drivers. (Instead, please connect them to power supply
separately.)
Attention: NEVER connect power and ground in the wrong direction, as it will damage
the M24/MD28.
10 Selecting Microstep Resolution and Driver Output Current
This driver uses an 8-bit DIP switch to set microstep resolution, and motor operating
current, as shown below:
10.1 Microstep Resolution Selection
Microstep resolution is set by SW5, 6, 7, 8 of the DIP switch as shown in the following
tables:
10.1.1 MD24
Microstep
Steps/rev.
SW5
SW6
SW7
SW8
2
400
OFF
ON
ON
ON
4
800
ON
OFF
ON
ON
8
1600
OFF
OFF
ON
ON
16
3200
ON
ON
OFF
ON
32
6400
OFF
ON
OFF
ON
64
12800
ON
OFF
OFF
ON
128
25600
OFF
OFF
OFF
ON
5
1000
ON
ON
ON
OFF
10
2000
OFF
ON
ON
OFF
20
4000
ON
OFF
ON
OFF
25
5000
OFF
OFF
ON
OFF
40
8000
ON
ON
OFF
OFF
50
10000
OFF
ON
OFF
OFF
100
20000
ON
OFF
OFF
OFF
125
25000
OFF
OFF
OFF
OFF

MD24 / MD28 –Hardware Description
11
10.1.2 MD28
Mikrostep
Schritte/Umdr.
SW5
SW6
SW7
SW8
2
400
ON
ON
ON
ON
4
800
OFF
ON
ON
ON
8
1600
ON
OFF
ON
ON
16
3200
OFF
OFF
ON
ON
32
6400
ON
ON
OFF
ON
64
12800
OFF
ON
OFF
ON
128
25600
OFF
OFF
OFF
ON
256
51200
ON
OFF
OFF
ON
5
1000
ON
ON
ON
OFF
10
2000
OFF
ON
ON
OFF
20
4000
OFF
OFF
ON
OFF
25
5000
ON
OFF
ON
OFF
40
8000
ON
ON
OFF
OFF
50
10000
OFF
ON
OFF
OFF
100
20000
ON
OFF
OFF
OFF
200
40000
OFF
OFF
OFF
OFF
10.2 Current Settings
For a given motor, higher driver current will make the motor to output more torque, but at
the same time causes more heating in the motor and driver. Therefore, output current is
generally set to be such that the motor will not overheat for long time operation. Since
parallel and serial connections of motor coils will significantly change resulting inductance
and resistance, it is therefore important to set driver output current depending on motor
phase current, motor leads and connection methods.
Phase current rating supplied by motor manufacturer is important in selecting driver
current, however the selection also depends on leads and connections.
The first three bits (SW1, 2, 3) of the DIP switch are used to set the dynamic current.
Select a setting closest to your motor’s required current.
10.2.1 MD24
Peak current [A]
RMS [A]
SW1
SW2
SW3
1,00
0,71
ON
ON
ON
1,46
1,04
OFF
ON
ON
1,91
1,36
ON
OFF
ON
2,37
1,69
OFF
OFF
ON
2,84
2,03
ON
ON
OFF
3,31
2,36
OFF
ON
OFF
3,76
2,69
ON
OFF
OFF
4,20
3,00
OFF
OFF
OFF
Note: Due to motor inductance, the actual current in the coil may be smaller than the
dynamic current settings, particularly under high speed condition.

MD24 / MD28 –Hardware Description
12
10.2.2 MD28
Peak current [A]
Nennstrom [A]
SW1
SW2
SW3
2,80
2,00
ON
ON
ON
3,50
2,50
OFF
ON
ON
4,20
3,00
ON
OFF
ON
4,90
3,50
OFF
OFF
ON
5,70
4,10
ON
ON
OFF
6,40
4,53
OFF
ON
OFF
7,00
5,00
ON
OFF
OFF
7,80
5,57
OFF
OFF
OFF
Achtung: Durch die Induktivität des Motors, kann der aktuelle Motorstrom kleiner sein,
als der eingestellte Ausgangsstrom, insbesondere bei hohen Drehzahlen!
10.3 Standstill Current Setting
SW4 is used for this purpose. OFF meaning that the standstill current is set to be half of
the dynamic current, and ON meaning that standstill current is set to be the same as
dynamic current.
The current automatically reduced to 60% of dynamic current setting one second after the
last pulse.
Theoretically, this will reduce motor heating to 36% (due to P=I2*R) of the original value.
11 Wiring Notes
- In order to improve anti-interference performance of the driver, it is recommended
to use twisted pair shield cable.
- To prevent noise incurred in PUL/DIR signal, pulse/direction signal wires and motor
wires should not be tied up together. It is better to separate them by at least 10 cm,
otherwise the disturbing signals generated by motor will easily disturb pulse
direction signals, causing motor position error, system instability and other failures.
- If a power supply serves several drivers, separately connecting drivers is
recommended instead of daisy-chaining.
- It is prohibited to pull and plug connector P2 while the driver is powered ON,
because there is high current flowing through motor coils (even when motor is at
standstill). Pulling or plugging connector P2 with power on will cause extremely
high back-EMF voltage surge, which may damage the driver.

MD24 / MD28 –Hardware Description
13
12 Typical Connection
A complete stepping system should include stepping motor, stepping driver, power supply
and controller (pulse generator). A typical connection is shown as figure 10.
13 Sequence Chart of Control Signals
In order to avoid some fault operations and deviations, PUL, DIR and ENA signals must
abide by some rules, as shown in the following diagram (assuming J1 default setting is
upward-rising edge effective):

MD24 / MD28 –Hardware Description
14
Remark:
t1- ENA must be ahead of DIR by at least 5µs. Usually, ENA+ and ENA- are NC (not
connected). See “Connector P1 Configurations” for more information.
t2- DIR must be ahead of PUL effective edge by at least 5µs to ensure correct direction;
t3- Pulse width not less than 1.5µs
t4- low level width not less than 1.5µs.
14 Protection Functions
To improve reliability, the driver incorporates some built-in protections features.
Over-voltage protection
When power supply voltage of the MD24 exceeds +52VDC or of the MD28 exceeds
+96VDC, protection will be activated and power indicator LED will turn red. When power
supply voltage is lower than +22VDC, the driver will not works properly.
Coil-ground Short Circuit Protection
Protection will be activated in case of short circuit between motor coil and ground.
Over-current Protection (only MD28)
Protection will be activated when continuous current reaches to 14A.
Wrong Motor Connection Protection (nur MD28)
Protection will be activated when the motor is connected in a wrong way.
Note: When above protections are active, the motor shaft will be free or the LED will turn
red. Reset the driver by repowering it to make it function properly after removing above
problems.
Attention: Since there is no protection against power leads (+,-) reversal, it is critical to
make sure that power supply leads correctly connected to driver. Otherwise,
the driver will be damaged instantly.

MD24 / MD28 –Hardware Description
15
15 Problem Symptoms and Possible Causes
Symptoms
Possible problem
Motor is not rotating
No power
Microstep resolution setting is wrong
DIP switch current setting is wrong
Fault condition exists
The driver is disabled
Motor rotates in the wrong
direction
Motor phases may be connected in reverse
The driver in fault
DIP switch current setting is wrong
Something wrong with motor coil
Control signal is too weak
Control signal is interfered
Erratic motor motion
Wrong motor connection
Something wrong with motor coil
Current setting is too small, losing steps
Current setting is too small
Motor stalls during acceleration
Acceleration is set too high
Power supply voltage too low
Inadequate heat sinking / cooling
Excessive motor and driver
heating
Automatic current reduction function not being utilized
Current is set too high