Stepper Motor

USER'S MANUAL

FOR

VMC-SMC

STEPPER MOTOR

CONTROLLER INTERFACE

FOR

VMC-8509 KITS

PERIPHERALS PVT. LTD.

WB-10, Shakarpur, Delhi-110 092. Phone : 91- 11- 22462826 Fax : 91-11-22515127 E-mail : [email protected] Website : www.vinytics.com

Table of Contents

INTRODUCTION ......................................................................................... 1

SPECIFICATION ........................................................................................ 1

FEATURES................................................................................................ 1

WORKING OF STEPPING MOTOR ........................................................... 2

Starting and Stopping Under Load ....................................................... 4

Speed Control of Stepper Motor ........................................................... 4

OTHER INSTRUCTIONS ............................................................................ 7

Connector Details ................................................................................ 8

Vinytics VMC-SMC Users Manual

VMC-SMC Users Manual VMC-SMC Users Manual

INTRODUCTION

Digital control systems have come to stay. They are entering into allbranches of engineering. There are many systems to monitor variousprocesses and give out control signals in the form of digits but thereis only one device to convert these digital pulses into preciseincremental motion and that device is stepping motor. Steppermotor is a device which converts digital pulses into precise angularor liners steps of desired value.

SPECIFICATION

q Permanent Magnet D.C. Stepping Motors two phase Bifilar wound.q Step angle : 1.8° ±5% Non-cumulative.q Step/Revolutions : 200.

FEATURES

v Instantaneous response to control pulses.v Holds on to the position infinitely in static condition.v No burn-out due to locked rotor.v Speed can be varied over a wide margin from 0-10,000 steps/

sec. Equivalent to 0-3,000 RPM.v High torque to inertia ratio. Can be over-driven without damage.v Can be programmed in three parameters namely, speed, direction

and number of steps.

Stepping Motors differ from conventional Servo Motors in followingrespect :

Ø There is no control winding in stepping motors. Both windings areIdentical.

Ø The stepping rate (speed of rotation) is governed by frequency ofswitching and not supply voltage.

STARTING AND STOPPING UNDER LOADThere is a limit for every type of stepping motor as regards thespeed at which it will start and stop without loosing step. The limit isdue to load torque as well as load intertie. To overcome thisacceleration and declaration techniques have to be employed.Acceleration means stepping rate on switching should be very lowand should increase to desired level gradually depending on inertiato be encountered. Acceleration/deceleration may be as high as1000 to 3000 steps/sec.

SPEED CONTROL OF STEPPER MOTORThe program initializes the 8255 (P1) in order to make port. A asoutput port. The PA0 to PA3 is connected through buffer and drivingcircuit to the winding of the stepper motor. The codes for clockwisemovement of stepper motor are FA, F6, F5 and F9 (refer switchingsequence). These code are to be output in the sequence they arewritten. In case of anti-clock wise movement of the stepper motor,output codes are as F9, F5, F6 and F4. The delay routine is calledto generate the delay (max. of about 1 Sec.) between the steps.This delay can be changed to make faster steps. The minimumdelay depends upon the maximum speed of the stepper motorspecified.

The speed for steps can be varied by changing the content at 2031-2032 and 2037-2038. These values are taken by register pair DEand a corresponding delay is generated. Both the delays are addedup to give the final delay. The individual delay can be calculated by(24N + 17) X basic Machine Cycle, N#O. When N is the numberstored in D register pair.

The following is program for Vinytics 8085 Kits.

Starting address of the program : 2000

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Switching Sequence

STEP SW-1 SW-2 PH-1 PH-2 A-2 B-2

1 1 2 1 0 1 0 0 1 0 12 1 4 0 1 1 0 0 0 0 13 3 4 0 1 0 1 1 0 0 14 3 2 1 0 0 1 1 0 0 0

1 0 1 00 0 1 00 1 1 00 0 1 00 1 0 1

The above switching Sequence/Logic will move shaft in one direction.To change direction of rotation read the sequence upward.

The specified torque of any stepping motor is the torque at stand still(holding torque). This torque is directly portional to the current in thewinding. The current in winding is governed by the D.C. resistanceof winding. As the switching sequence starts the inductive reactanceof the winding which increases with the frequency of switchingopposes the rise of current to desired level within the time given forone step depending upon the speed of stepping. This is mainly dueto L/R time constant of winding. The drop in current level causesdrop in torque as the speed increases. In order to improve torque athigh speeds it is necessary to maintain current at the desired level.This can be done by one of the following methods:

1. By increasing supply voltage and introducing current limitingresistances in each phase. Introduction of resistances improvesthe time constant of winding. Seven to nine time the windingresistance in each phase will give very good improvement intorque/speed Characteristics.

2. By using a constant current source with or without a chopperinstead of using a constant voltage source which will give evenbetter performance.

PHASE-1 PHASE-2

A-1 B-1 A-2 B-2

Ø A pulse input two phase clock (instead of continuous pulses) willmove the shaft of motor by one step for every pulse, thus numberof steps be moved can be precisely controlled.

Ø When there is no pulse input, the rotor will remain locked up inthe portion in which the last step was taken since at any time twowindings always energized which lock the rotorelectromagnetically.

Ø Stepping motors can be programmed in three parameters namely:a) Direction,b) Speed andc) Number of Steps

WORKING OF STEPPING MOTOR

The stepping action is caused by sequential switching of supply tothe two phases of the motor as described in switching diagram. Allstepping motors are of bifilar type with six leads. Watch of the twoPhases of motor has double winding with a centre tap switching thesupply from one side to another of a phase causes reversal ofmagnetic polar without actually reversing the polarity of supply. Forstep input sequence gives 1.8° (full) after and eight step inputsequence give 0.9° (half) step function.

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PROCEDURE

1. Switch on 8085 kit.2. Connect 26 pin FRC cable from 8255-I connector of kit to 26 pin

connector of SMC Card at CN1 Connector.3. Connect Stepper motor cables to given stepper motor card at

CN4 connector.4. Connect stepper motor power supply connector at CN2 connector

of SMC module.5. Enter the given program from 2000 Address and Execute from

2000 Address.6. See the speed of motor as defined delay.

PROGRAM

2000 3E 80 MVI A,80 Initialize all ports as outports.

2002 D3 03 OUT 032004 3E FA START: MVI A,FA2006 D3 00 OUT 00 Output code for step 0.2008 CD 30 20 CALL DELAY Delay between two steps.200B 3E F6 MVI A,F6200D D3 00 OUT 00 Output code for step 1.200F CD 30 20 CALL DELAY Delay between two steps.2012 3E F5 MVI A,F52014 D3 00 OUT 00 Output code for step 2.2016 CD 30 20 CALL DELAY Delay between two steps.2019 3E F9 MVI A,F9201B D3 00 OUT 00 Output code for step 3.201D CD 30 20 CALL DELAY Delay between two steps.2020 C3 04 20 JMP START Start.

Delay Routine

2030 11 00 01 DELAY: LXI D,0100 Generate a Delay.2033 CD A6 03 CALL DELAY2036 C9 RET

To move the Motor in the reverse direction, Change the contents at

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PC4 PC5

PC2 PC3

PC0 PC1

PB6 PB7

PB4 PB5PB2 PB3

PB0 PB1

PA6 PA7

PA4 PA5

PA2 PA3PA0 PA1

PC6 PC7

GND GND

STEPPER MOTOR

Connector Details at CN1

U1 U2 U3 U4

+5VGND

MotorSupply

NC

26

1 2

25

CN1

CN2

CN4 CN3

GN

D

GN

D

PA1

PA2

PA0

PA3

MO

TOR

SU

PP

LY

GN

DG

ND

PA1

PA2

PA0

PA3

U5


the addresses as mentioned below :

Address Forward Reverse

2005 FA F9200C F6 F52013 F5 F6201A F9 FA

F The 7Pin Connector Details of CN4 are as follows :

Stepper Motor Voltage: 12/5 V as per the Stepper Motor

PA0 Amplified OutputPA1 Amplified OutputPA2 Amplified OutputPA3 Amplified Output

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MOTOR GND GND PA1 PA2 PA0 PA3

SUPPLY

560ΩΩΩΩΩ

0.1 µµµµµd

330 ΩΩΩΩΩ

0.1µµµµµd100ΩΩΩΩΩ1W

270ΩΩΩΩΩCL100ECP 055

STEPPER DRIVER

VOLTAGE 5 TO 36V

10Ω,Ω,Ω,Ω,Ω,1W

THE CIRCUIT REMAINS SAME FOR ALL FOUR WINDINGTHE INPUTS ARE TAKEN FROM PA1, PA2 AND PA3

Note : To change the speed of the stepper motor, change data at memorylocation 2031 and 2032 in the programme. e.g. 2031 00,

2032 02

Stepper Motor

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