How to apply SMS in Real-Time Control Systems

How to apply SMS in Real-Time Control Systems

by JAMES AGAJO, DEPARTMENT OF ELECTRICAL/ELECTRONICS ENGINEERING, AUCHI POLYTECHNIC, ACUHI

Abstract  - Advancement in technology  has given rise to exploring ways of advancing control of devices beyond the environment in which it is been operated. This is the essence of this research. This work is an application of Global system for mobile communication within a coverage network from a particular telecommunication service provider where two mobile stations communicate with each other.  The mobile phone at the receiving end is stationed to receive SMS messages which are decoded by an interface to carry out control of various devices. This work bridges the digital gap needed for control of high technology equipment. Adopting this real time integrated technology will enhance optimal performance in engineering systems by taking care of sluggish performance to avoid oscillations.

Keywords: SMS, Real-Time, Remote, Control, Interface, Industrial control

I. INTRODUCTION

Today the world is experiencing a revolution technologically. Such challenges have made it necessary for scientist and Engineers to intensify their specific research areas to meet up the challenge pose to us as engineers. The consequence of not meeting up with present challenges could be enormous. The implication could be loss of valuable Man hour and low accuracy. However quality service ability to conform with the challenges pose to us by state of the art applications have necessitated the need for adopting real-time personal positioning system for indoor and industrial application.  Real-time personal positioning system for indoor and industrial application (emphasis: SMS remote controller with is a high-tech device that has the facility to control a device from a remote area, this can be achieved using a coverage network from some telecommunication service provider.

Terrestrial network make use of Radio for transmission which date back to its origin when an Italian inventor Guglielmo Marconi sends the first wireless message overseas. Besides being used for military communications, the new medium will become a significant factor in many people's lives, broadcasting sporting events, music, and news. From the 1930s through the 1950s, radio became a major form of entertainment in America. [2]. SMS appeared on the wireless scene in 1991 in Europe, where digital wireless technology first took it root. The European standard for digital wireless now known as GSM. In North America, SMS was initially made available built by early pioneers such as BellSouth mobility and Nextel in 1998[11]. Microcontroller is incorporated into the system which ensures synchronous or asynchronous data transfer. Today digital signal processing has made communication easier which in a very general term takes samples of a signal with the ADC converter[3]

Although SMS Controller in entirety does not follow real time, this is basically because of the fact that there is time lag between the sent and receive message. The fact remains that response between the time the message is received and the interface that carries out the conversion can be made short. This can be achieved as can be decided by the osscillator connected to the microcontroller.

All microcontroller require a clock, it is use to synchronize all all the activities within the microcontoller

Period = 1/frequency

A crystal osscillator of 12 mega hertz will make the microcontroller to perform

1/12 x 1000000= 83333.333333333333333333333333333

It will perform 8333.3333333333 instructions per second [7]

Filter circuit is incoporated into the system to realise  an undistorted performance this filters out high frequency ripples the capacitor use to realise this value about 30 pico farad.[8]. The application of SMS remote controller are enormous aside industrial control , it stand out as one  outstanding security device used in monitoring burglary, it can be used as an anti-theft device from a remote position one could in a country as far as Brazil and monitor the status of his appliances at home in Nigeria

The GSM network offers a wireless infrastructure which extends your reach to anywhere in the world.  There are several means to tap onto this infrastructure as a communication medium.  One way is to use a direct data call to connect a point-to-point data link from one place to another.  Or, to log into the World-Wide-Web via GPRS.  A simple method is also via Short Message System (SMS). Which ever means is used, a user wants to exchange or send data or information from one point to another.  We will describe here of how to use an AT command on mobile phones to be as a GSM communication information node.  This will be the cheapest means to create your own DIY remote messaging system.  Selecting a Mobile Phone or GSM module Use HyperTerminal to do Simple Testing of the PhoneSMS reading and SMS sending to the Phone from HyperTerminal Interfacing a micro-controller system to the Phone.[10]

Radio Transmission

Terrestrial network make use of Radio for transmission which travel which move signals to and fro along a line of sight with a free space loss of

L=(4πl/λ)2= (4πfl/c)2

λ is wavelength,  c is speed of light.[1]

Transmission Technology

TDMA and CDMA are the appropriate technology require for this work they are digital transmission technologies that support GSM.[11]

II. SELECTING A MOBILE PHONE OR GSM MODULE

The first condition is to making sure that the phone has a serial port. It is necessary to use a phone that is GSM AT compliant.  Then, it is possible to communicate with the phone through AT commands.  Since all Sony Ericsson mobile phones, the same data connector on the phone.  the GSM is connected using  RS232 data cable.  The tested phones are : T39, T65, T68, T68i, R320s, R520m, T310, T316, T610, T618, T628, T630.

Siemens mobile phones : S25, S35, S45, S55, S65, C35, C45, C55, M35, ME45, M50, MT50. GSM modules: see our OEM TC35 Siemens module.

Most Nokia phone is AT compliant only through the IrDA port.  The data connector port uses a Nokia protocol called the FBus which is much more complicated.

IV. MODE OF OPERATION

This work can be used to control up to 8 devices by sending a specific SMS message with any mobile phone. Its very useful at the cases that, at the place we have the devices, we have not a wired telephone line. This can be achieved using an  old ericsson mobile phone.  The controlling that we can do to the devices, is only ON or OFF.

(1)   AT+CPMS="ME"     (Select the phone memory "ME")

(2)   AT+CMGR=1            (read received message from memory

position 1)

If the mobile phones will response with:

AT+CMGR=1[CR][CR][LF]   (this message its sent when there is no message in the phone memory)

+CMS ERROR: 500[CR][LF]

At this case the AVR it will send again the commands 1 & 2

If the mobile phone will response with: AT+CMGR=1[CR][CR][LF]   (this message its sent when a new message arrive in the phone memory)

+CMGR: 0,,26[CR][LF]

0791039624910000240C91xxxxxxxxxxxx00003001205151302108B1180C068BC162[CR][LF]OK[CR][LF]

(xxxxxxxxxxxx is the phone number of the sender)

the microcontroller will decode the septets message to octets, execute it (arm or disarm the relays) and send the command AT+CMGD=1 delete the received message from memory position 1) to delete the message from the phone memory.

You can see the voltage of the Port B with any voltmeter if you have +5 or 0v voltage, to check if the command you send, for example"11001010", its executed.[10]

9600 bps baud rate will work (actually, the module will accept all the baud rate setting, any selection will work).  The other parameters are : Data Bits (8), Parity (None), Stop bits (1), Flow Control (None).On the left bottom corner of the HyperTerminal window will show a "Connected 0:00:44" which shows that the connection is available and the time that the connection has been established. The following are some simple AT commands :

Call Control

AT                Attention

ATA            Answer Command

ATD            Dial Command

ATH            Hang Up Call

Type "AT" on the HyperTerminal.   The GSM phone will respond with an "OK". Typing "AT" on the HyperTerminal.   The GSM phone will respond with an "OK".This is the simplest command to tell the mobile phone to go on attention.  It doesn't do anything.  However, this is also a means to test if the phone responds on the baud rate and all the serial settings. The GSM phone will send a "RING" message, when it picks up an incoming call from the network. With that, we have the means to communicate to the phone via serial port.  Thus, we could build a system to remotely send or receive data.[9]

V.  CONCLUSION

Today we experience a big digital gap between the developed and the developing countries. To close this gap there is need to adopt seamless technologies. In most IT applications we also experience the hazard caused by inability to be always close to some of the devices we use. With the cooperation of telecommunication service providers, control and monitoring   of systems from remote locations will solve some of these problems. Finally, the need to adopt SMS remote controllers that use sample block control system in most devices is expedient with rising case of theft, insecurity, burglary, industrialization and globalization.

References

[1] A. Bruce Carlson, Paul B. Crilly and Janet C. Ruledge

Communication Systems an introduction to signals  and noise in

electrical Communication,Fouth edition p106

[2] B.RAM:(2005), Fundamentals of microprocessors and

Microcomputers, sixth edition p9,7.1

[3] Douglas v. Hall, 2004. Microprocessor  and Interfacing, Tata

McGraw-Hill ,         second edition pp273-300,pp330-344

[4] Further work on SMS remote controllerL:(2007),          wwwallegromicro.com

[5] I.J. NAGRATH and M. GOPAL Control Systems Engineer,fouth

edition p514,515,516

[6] Literature on Radio and wireless communication and l, Microsoft ®

Encarta ® 2006. © 1993-2005 Microsoft Corporation.

[7] Mike JamesL2001,Microcontroller Cookbook PIC & 8051,second

edition p65,70

[8] V.K MEHTA and ROHIT MEHTA(2006), Principle of Electronics

revised edition p163

[9] Work on SMS remote controllerL2007,http://www.lancos.com

[10] USB DEVELOPER,(2007), http://www.USB DEVELOPER.COM.

[11]Web Proforum tutorials 2002,http://www.iec.org

BIBLOGRAPHY

James Agajo has just completed a Master Degree in Electronics and telecommunication Engineering and also possesses a Bachelor degree in Electronics and Computer Engineering from the Federal University of Technology Minna Nigeria. His interest is in intelligent system development with a high flare for Engineering and Scientific research. He is presently on secondment with UNESCO TVE as a supervisor and a resource person. James is presently registered with the Nigeria Society of Engineers.

Omeimen Ujuanbi bagged a Bachelors degree in Physics in 1989 from the then Bendel State University (now Ambrose Alli University, Ekpoma). His undergraduate project work was on speed control of a D.C motor using Silicon Controlled Rectifier (SCR). In 1994, he obtained a Master’s degree in Applied Geophysics and a Doctorate degree in Engineering Geophysics from the same University.   He has taught and researched in the University for well over a decade. He has six textbooks to his credit which are used at undergraduate levels in Nigerian Universities. He has published at local and international journals. He has also attended and delivered research papers in scientific conferences over the years.  He has just completed one year Sabbatical appointment with Shell Petroleum Development Company, Port Harcourt-Nigeria. He is a member of The Nigerian Institute of Physics (NIP), National Association of Mathematical Physics and Geophysical Association of Nigeria (GAN).