1

Step Motor Control System by means of Human Machine Interface and Programmer Logic

Controller

J.C. Quezada(1)

, E. Flores(2)

, J. Bautista(3)

, A. Lpez(4)

(1),(2)

Universidad Autnoma del Estado de Hidalgo, Escuela Superior de Tizayuca, Tizayuca, Hidalgo, Mxico (3)

Universidad Autnoma del Estado de Mxico, Valle de Teotihuacn, Estado de Mxico, Mxico (4)

Centro de Investigacin y de Estudios Avanzados del IPN, Departamento de Ciencias Computacionales, D.F.,

Mxico

Abstract: Step motors are widely used in motion

control systems and they require the driver to provide

high precision in pulses synchronization in order to

obtain high precision in motor speed and thus in the

mechanisms motions, including rotation direction of

the set step motor-mechanism. In this work a control

system for a step motor is designed and implemented

on a test bank; the system consists of a GUI (Graphical

User Interface) to interact with the operator. The HMI

(Human-Machine Interface) has been designed on

proprietary software and considers, to the operator,

rules for control and monitoring of system conditions.

The HMI is interconnected with a PLC (Programmable

Logic Controller) in which the control rules and system

protections are implemented using Ladder Diagram

Language (or Ladder Logic, LL).

Key Words: Graphical User Interface, GUI; Human-

Machine Interface, HMI; Ladder Logic, LL;

Programmable Logic Controller, PLC; Step motor.

1. Introduction

At industry, many manufacturing systems and

continuous processes use different types of motors (AC-

motors, DC-motors and Step motors). Step motors are

commonly used for accurate motions of mechanisms

required by sophisticated machines and/or production

plants [1],[2]. The step motor control has been

traditionally carried out by using microcontroller

technologies, Field Programmable Gate Array (FPGA)

and Digital Signal Processing (DSP); however,

nowadays, industrial processes and machines are often

controlled through algorithms developed on

Programmable Logic Controllers (PLC) allowing to

modify them in an easy, quick and secure way before

new control requirements of the machines or plants

[3],[4]. PLC applications related to motors have been

primarily focused toward its startup and stopping

control and remote control by means of speed

controllers (driver). Logical programs developed in

PLC must guarantee the process reliability through

rules that allow to include all the risk possibilities as

much for people as for the plant (in this work, the step

motor) [6]. For this project the control logic has been

developed in Ladder Logic (LL) since it is still the most

used in PLC and therefore in process control [5],[6].

On the other hand, Human-Machine Interfaces

(HMI) at the present time are employed to represent in

an identical way the reality of the processes, allowing

the operators an interrelation between the physical

equipments of the plant with the virtual equipments of

Graphical User Interfaces (GUI) [7]. Besides, graphical

interfaces allow including events (mainly by means of

the computers mouse) in order to carry out control

actions and protection of the system equipments, as

well as to read the memory registers containing

information about the PLC variables and could using

their states to indicate, through color changes in virtual

equipments, the condition that those variables keep into

the real process and thus to facilitate to system operator

to make decisions [8].

This work shows to PLC as the step motor control

system and to HMI as the monitor through the designed

GUI. The system development is stated with a logic

about the variables state-event to be realized:

protection and/or animation through color.

2. Problem statement

In order to design the control algorithm, have been

considered the following aspects:

1. General requirements about the step motor control

system: variables to be controlled and/or monitored.

2. Employed control devices: HMI - PLC - Step motor.

3. The control algorithm development on LL.

4. GUI design for system control and monitoring.

2

2.1. System requirements

Basic system function is to control a six-wire two-phase

step motor in high torque configuration. The control

system must have industrial security conditions, that is

to say, IN-OUT selection, and physical (of field) and

virtual (on HMI) emergergency stop. Control stage

have to involve an option to five preset velocities and

an option to variable speed, as well as for rotation

change in both conditions. Control type selection,

preset-variable; rotation direction, left-right; system in-

out condition, and preset and variable velocities

buttons, must have of virtual type.

The step motors electric connection is shown in the

next circuit (Figure 1) and the motor step sequence in

the Table 1.

Orange

White

Blue

M

RedBlack

Yellow

Figure 1. Motor electrical circuit

Table 1. Motor step sequence

White/

Black Orange Red Blue Yellow

Ste

p

1 + - -

2 + - -

3 + - -

4 + - -

2.2. Control devices

The GUI has been developed on software by means

of a proprietary HMI installed on a PC, and reads and

writes data into the PLC register variables, in order to

be manipulated and/or monitored and assigns them the

same TAG or label. TAG assignation is based on the

Instrument Society of America (ISA) norm [12].

The employed PLC is modular type [9],[10] with

capacity for modules endowed of inputs and outputs for

24 VCD digital signals, as in this work; however, also

can manipulate analogical signals. The step motor

control system is shown in Figure 2.

Digital inputs and outputs are addressed through %I

and %Q respectively; in case of the inner signals of the

PLC memory, they are addressed through %M for

digital signals and %R for 16-bits registers [11].

Variables statement and addressing in the PLC are

shown in Table 2. The same variables TAG is used for

stating points in the HMI development.

Fuen

te

CPU

%I

%Q

USB - RS485

PLC

HMI

S tep Motor

Figure 2. HMI - PLC - Step motor

Table 2. HMI PLC variables addressing

2.3. Control algorithm development

Figure 3 shows the main control diagram; the first

algorithm line is related to the system security

conditions: physical and virtual stop, and system

conditions (HS_FISICO, HS_VIRTUAL and

SIST_D_F, respectively). Line two is proposed in order

to make sure that at any system stopping, the motor

startup-stopping signal A_P_MOTOR becomes zero.

Subsequently, there are two subroutines with crossed

contacts of the signal TIPO_CTL conditioned to only

one at once is activated; first subroutine is for

controlling the preset velocities, and the second one for

controlling variable speed of the step motor.

For controlling the preset velocities a timer block

is employed for determining each velocity (Figure 4);

the timers output signal are inputs to a counter block

with a preset value of four for four step control (Figure

5).

Address TAG Description

%I129 HS_FSICO Physical emergency stop

%M1 HS_VIRTUAL Virtual emergency stop

%M2 A_P_MOTOR Motor start up/stopping

%M3 SIST_D_F In-Out system

%M4 TIPO_CTL Control type: preset velocities variable

speed

%M5 SENT_GIRO Motor rotation direction

%M10 COND_SIST System conditions

%M11 VEL_1 Preset speed 1

%M12 VEL_2 Preset speed 2

%M13 VEL_3 Preset speed 3

%M14 VEL_4 Preset speed 4

%M15 VEL_5 Preset speed 5

%Q17 MOTOR Motor start up-stopping

%Q21 BOB_NAN orange coil

%Q22 BOB_ROJA red coil

%Q23 BOB_AZUL blue coil

%Q24 BOB_AMA yellow coil

%R35 LEC_VEL Speed reading

3

Figure 3. Main algorithm

Figure 4. Timer block

Figure 5. Counter block

Figure 6. Equal comparative block

Figure 7. Line for a motor coil

From the counter block, the real count value is taken

out from the corresponding register in order to be

compared through an equal comparative block (Figure

6); the output of this block is employed in the

energizing sequence of the coils, as shown in Figure 7.

It can be seen in Figure 6 that the equal comparative

block is enabled by the signal selecting the control type

TIPO_CTL. In Figure 7 the rotation direction sequence

of the step motor is enabled through SENT_GIRO.

The variable speed control employs a timer block for

which its desired value register is manipulated by

means of the GUI, as shown in Figure 8.

. Figure 8. Timer block to variable speed

4

For counting, comparison and points sequence, the

same algorithm structure is used, which guarantee that

at change of control type and of motor rotation, the

sequence holds since the registers in the used blocks are

the same and the containing information is taken out

independently from the time in which the change of

control type and of rotation direction are carried out.

2.4. GUI design

The developed GUI shown in Figure 9 presents the

protection elements, the physical emergency stop

through a security label (monitoring signal comes from

field), and the following virtual elements (signals

modified from the HMI or read from the PLC

registers): emergency stop represented by means of a

retentive emergency button, selector of in-out

condition, selector of control type preset-variable

speed, selector of rotation left-right direction, button for

startup-stopping of the step motor, five buttons for

selecting preset velocities, an analogical and digital

speedometer, and buttons for increasing or decreasing

the step motor speed in the variable speed control

mode.

The HMI logic has been developed combining the

programming of states of the variables with the

programming of events conditioning an action. Figure

10 shows the GUI events diagram and the states of the

variables, in the PLC, about the system protections:

HS_FISICO, HS_VIRTUAL and SIST_D_F.

Symbol indicates the execution, by means of the

computers mouse, of an action on the GUI virtual

instruments, which at the same time carry out an action

on the HMI points variables interrealted with the PLC

data registers.

Velocidad 1

Velocidad 2

Velocidad 3

Velocidad 4

Velocidad 5

Velocidades

DERIZQ

DENTROFUERA

Giro

Condiciones del Sistema Control de Velocidades

I

OO

PARO DEEMERGENCIA

PO W ER SUPPLY

GE FanucSERI ES 9 0 - 3 0

PRO G RAM M ABLECO NTRO LLER

+24VDCO UTPUT-

100- 240VAC 40A50 / 60HZ

BATTERY

PW RO K

RUNBATT

A 1 2 3 4 5 6 7 8

FB 1 2 3 4 5 6 7 8

A 1 2 3 4 5 6 7 8

FB 1 2 3 4 5 6 7 8

A 1 2 3 4 5 6 7 8

FB 1 2 3 4 5 6 7 8

A 1 2 3 4 5 6 7 8

FB1 2 3 4 5 6 7 8

A 1 2 3 4 5 6 7 8

FB 1 2 3 4 5 6 7 8

PARO DE

EMERGENCIA

Predeterminadas

HMI - PLC - MOTOR A PASOS

VARDET

Tipo de Control

0300

150 22575

RPM

000

Figure 9. GUI in edition

Based on the control rules, the step motor startup

and stopping can be achieved if HS_FISICO,

HS_VIRTUAL and SIST_D_F are equal to zero, which

guarantee that in absence of electricity feed for the

physical emergency stop, the step motor stops. In the

diagram, the actions for changing the state of a variable

into the PLC memory and/or the element color in the

GUI, are indicated. Any of these three signals put the

A_P_MOTOR at zero when they are activated.

Figure 10. Logic of HMI protections

Changing the step motor rotation direction is

independent from the speed control type being

operated. For step motor control at preset velocities,

Figure 11 presents the logic of events and actions

corresponding to the speed selection 1 (VEL_1); for

selecting other options is the same procedure.

Figure 11. Logic of the preset speed control in HMI

TIPO_CTL VEL_1 = 1

VEL_2=VEL_3=VEL_4=VEL5=0

0

HS_FISICO

Label PARO DE

EMERGENCIA hidden in the

GUI

A_P_MOTOR=0

Label PARO DE

EMERGENCIA

oscillating in GUI

0

1

HS_VIRTUAL

Label PARO DE

EMERGENCIA at GUI in

green color

A_P_MB=0

Button PARO DE

EMERGENCIA

at GUI in red color

0

1

SIST_D_F

At selector CONTROL in

green color and knob positioned

in GUI

A_P_MB=0

At selector FUERA in red color

and knob positioned in GUI

0

1

5

Figure 12. Logic of the variable speed control

The variable speed control type is manipulated by

means of the HMI in order to increase or decrease the

used register value of the timer block.

3. System testing

Two types of tests were carried out to the step motor

control system, that is:

System security, and

Step motor speed control.

Figures 13 and 14 show the security tests of the

control system; in Figure 12 the HS_VIRTUAL is

activated, button and step motor in red color, and

SIST_D_F is in out-position with red letters.

Figure 13. HS_VIRTUAL and SIST_D_F at 0

In Figure 14 it can be observed that HS_FISICO is

activated through the label centered at the GUI; the step

motor stays in red color. The HS_VIRTUAL is no

longer active and the button is in green color.

Figure 14. HS_FISICO at 0

Figures 15 and 16 show the control system at preset

velocities TIPO_CTL in 0, and with the left rotation

direction SENT_GIRO in 0 at Figure 13; while in

Figure 15 SENT_GIRO is in 1 showing the message

corresponding to the selector in green color and the

knob in its corresponding position. Also, the system

conditions at normal operation are showed, that is to

say, HS_FISICO = HS_VIRTUAL = SIST_D_F = 1,

and the motor and stop button in green color; and the

emergency stop label corresponding to the physical

stopping is not showed in the GUI. The on-off switch of

the step motor is activated and A_P_MOTOR = 1 is in

wine color.

Figure 15. System operation with left rotation direction

In the case of variable speed control of the step

motor, the configuration is such that the changes in the

corresponding timer block last 5 milliseconds (ms) each

time the buttons of signal increment or decrement are

pressed, which allows having an accurate speed control,

TIPO_CTL Increasing %R31

Decreasing %R31

1

6

as can be seen in Figure 17 where the digital indicator

displays 1.05 rpm, and Figure 18 shows 85.71 rpm. The

interval can be modified in the GUI design.

Figure 16. System operation with right rotation direction

Figure 17. Variable speed control 1.05 rpm

Figure 18. Variable speed control 85.71 rpm

The maximum programmed speed of the system is

300 rpm for the variable speed control type, as shown

in Figure 19. Figure 20 presents a picture about the test

bank where the speed control system of a step motor

was implemented.

Figure 19. Maximum speed of the step motor

Figure 20. Test bank of the speed control system of a step

motor

4. Conclusions

New technologies for industrial processes automation

commonly employ PLC for sequence control, and HMI

for variables monitoring and manipulation with

animation in real time by means of GUI. The

programming by events and actions implemented in the

HMI allows support to the operators in the processes

interpretation and in the early solution to problems

and/or faults in the system, through programmed

alarms; however, also gives as a consequence the

7

necessity of highly qualified personnel in applying

those new technologies. The control algorithm and the

logic of events and actions allow optimize the pulse

sequence toward the step motor for a better speed

control of this.

5. References

[1] De Lucena, S.E.; Kaiser, W.: "Stepping-Motor-Driven

Constant-Shear-Rate Rotating Viscometer"

Instrumentation and Measurement, IEEE Transactions

on , Vol. 57, No.7, pp. 1338-1343, July 2008.

[2] Zhihuang Huang; Lin Li; Donghui Guo: "Design of

stepping motor driving module for automatic

microscope system" Anti-counterfeiting, Security, and

Identification in Communication, 2009. ASID 2009. 3rd

International Conference on, pp.328-331, 20-22 Aug.

2009.

[3] Ljungkrantz, O.; Akesson, K.; Fabian, M. and Yuan,

C.: Formal Specification and Verification of Industrial Control Logic Components IEEE Transactions. Automation Science and Engineering, Vol. 99, pp. 1-

11, Dec 2009.

[4] Gulpanich, S.; Tipsuwanporn, V.; Suesut, T. and

Tirasesth, K.: "Implementation Programmable Logic

Controller for THAILAND Industries" Computational

Intelligence for Modeling, Control and Automation,

2005 and International Conference on Intelligent

Agents, Web Technologies and Internet Commerce,

International Conference on, Vol. 2, pp. 234-239, Nov

2005.

[5] Johnson, D. Programmable Logic Controllers Control Engineering, pp. 83-90, Sep 2008.

[6] Konaka, E.; Suzuki, T. and Okuma, S.: "Safety

Verification of Programmable Logic Controller taking

into account the Physical Dynamics - Application to

Material Handling Robots" SICE 2003 Annual

Conference , Vol. 1, pp. 818- 823, Aug 2003.

[7] Mathiesen, M.L.; Vefling, H.; Indergaard, R. and

Aakvaag, N.: "Trial Implementation of a Wireless

Human Machine Interface to Field Devices" Emerging

Technologies and Factory Automation, ETFA '06. IEEE

Conference on, pp.189-193, Sep 2006.

[8] Hall, S.; Cockerham, K. and Rhodes.: "What's your

color? [human-machine interface design]" Industry

Applications Magazine, IEEE, Vol. 8, No. 2, pp. 50-54,

Mar/Apr 2002.

[9] W. Bolton: Programmable Logic Controllers, 4th

Edition, Elsevier, 2006, pp. 9-12.

[10] Domingo, J.; Gmiz, J.; Grau, A. and Martnez, H.:

Introduccin a los Autmatas Programables, 1st

published, VOC, 2003, pp. 124, 135.

[11] Ge FanucTM, PLC Serie 90TM - 30/20/Micro, Juego de

Instrucciones de la CPU, Manual de referencia GFK-

0467-SP, 2002, pp. 2-10,11,27,31.

[12] American National Standard, Instrumentation Symbols

and Identification, ANSI/ISA 5.1-1984 (R-1992), Jul

1992.

6. Authors Biography

Jos Carlos Quezada Quezada, is

an engineer in electronics by the

Technological Institute of Lzaro

Crdenas, Mexico, 1992. He

obtained his M.Sc. in Mechatronics

Engineering in 2008 at TESE. His

research is Instrumentation and

Automation.

Ernesto Flores Garca, Ernesto

Flores obtained his MSc in

Automatic Control specialty from

the CINVESTAV-IPN of Mexico

City, Mexico. He is currently a PhD

candidate in the same specialty and

Institution. He received his Engineer

degree in Aeronautics from the IPN

of Mexico. His research interests include

Electromechanical Systems Control, Servomechanisms,

Robotics, Microcontrollers, among others. MSc Flores

has worked as a university researcher-professor in

Control and Mathematics areas from 2004; nowadays

he is working at the Universidad Autnoma del Estado

de Hidalgo, Mexico.

Asdrbal Lpez Chau is an

engineer in electronics and

telecommunication by ESIME-IPN,

Mexico, 1997. He obtained his

M.Sc. in computer engineering in

2000 at CIC-IPN, Mexico.

Currently, he is pursuing his PhD,

working in the area of adaptive

classification algorithms for high speed data streams, at

CINVESTAV-IPN, Mexico.

Jorge Bautista Lpez, is an

engineer in communication and

electronics by ESIME-IPN, Mexico,

2002. He is candidate to master in

sciences by SEPI-IPN. Working

embedded systems with

microcontrollers and programmer

logic controllers.