Viper DC servomotor drive Manual V2.0.1
Contents
1. CONTROL PROGRAM 12 Volts MAIN POWER IN Direction and Step inputs e Fault LED and ka Estop out e Warn o ENCODER e MOTOR OUT Current Limit First lower the p setting to 50 and set Il to zero and d to zero Set the h command to zero also Slowly apply step pulses one at a time and the motor should start to turn Use the Command to see what the drives output PWM value is currently at Apply step pulses in the opposite direction and until the motor just stops turning Read the drives PWM value and write it down This is the value the h command needs to overcome the friction in the system Enter it and use the s command to save the setting VIPER gm PAGE 29 Viper command set Dataemn fo p nnnn Enter Proportional term i nnnn Enter Integral term d nnnn Enter Derivative term j nn Enter step size jump 1 nn Enter Loop term n nn Enter number of bank r nnnn Enter error range limit cnn Enter pwm Clip limit 100 450 h nn Enter hysterisis friction compensation b nn Enter Balance control motor offset f nnnn Enter Feed_Forward term t nnnn Enter encoder Trip limit ann Enter current parameter Read data 1 Read settings group 1 1 lt cr gt Returns N P I D L data 2 Read settings group 2 2 lt cr gt Returns F T PWM data 3 Read settings group 3 lt cr gt Returns A Real_current pot e Get servo error in Hex e lt cr gt 00A1 v Get software version v lt2. Input Fault and Warning Waring Output setting Trip Fault setting Encoder meu Motor Power Output Control Side Power Side Page 5 Viper 100F 200F Drive Connectors mu oe 12 Vols PROGRAM Direction and Step inputs Fault LED and Warn Estop out 00000 oO0O000 O o VIPER Ah MAIN MOTOR POWER OUT ENCODER O Differences between Viper 100 200 A and Viper 100 200F after 2011 The older Viper drives couldn t read actual Current They used a set value set by a trim pot and could only see if the motor current was above or below that The F series Viper 95 and 100 200 can read current and the max motor current is now a software The F series drives can run up to 300Khz step input vs 125 khz for the older drives Page 6 Differences Viper 100 200 Avs Viper 100 200F continued The baudrate for the serial connection is now 38400 baud vs the previous drive which were 9600 baud Low voltage detection is a new feature that detects whether main power on the V100F 200F is turned off and disables the drive until it comes back on It then soft starts after a 2 seconds Note position is cleared so the motor doesn t jump The viper 95 low voltage detection disables and locks drive when voltage dips This brownout detection protects the drive since the CPU can be unpredictable during low voltage situations On the V100F 200F power and motor connectors are
3. block connectors is highly recommended For a professional job use a crimp tool such as this one from http www action electronics com molex htm PHT 98 601 NON INSULATED OPEN BARREL AND D SUB V35 CONN PAGE 33
4. disconnect the 12volt to the control side to Reset power to the drive to reset the trip fault Adjusting the Current Warning pot The adjustable trim pot on the drive allows you to set a Warning current level that is less than the max motor current This can be set to indicate the machine is under excessive load cause by a dull cutter or jamming condition etc The warn doesn t trip the drive but flashes the Fault light 3 flashes and holds down the Stop output if the current stays high for more than 2 seconds When the load reduces the error goes away The Viper has 2 output signals One is to power a flashing LED on the front panel of the controller and the other should be connected to your Estop signal to stop the motion commands These are open collector outputs and can be parallel connected to multiple Viper drives Note Its important to connect the error outputs back to the breakout board to stop the control software PAGE 24 Viper Error Indicator LED F series When an error is flashed the Viper will hold down the Estop signal until the error is removed You can add a Fault override switch normally closed in this estop line to allow the operator to jog the machine while holding the switch to recover from a warning error It will flash the RED led a count indicating the error number LED error count Version 3 0 firmware Encoder Range warning r command Currentwarn Pot adjustment Under voltage
5. This is because the motor is pulled along by the incoming pulse train The Feedforward parameter can reduce high speed following error by adding a push that is proporional to the speed of the incoming step pulses Leave the f command to zero until you get the drive tuned with the PID and L parameters While running the motor read the error with the e command Increase the f command until the error becomes close to zero Start off slow and increase the speed while increasing the f command Too much Feedforward will create a leading following error Typically the F parameter may end up being close to the P parameter PAGE 20 Using Banks for storing multiple configurations The Viper drive allows you to setup 3 different preset configurations This allows the drive to be Jumper selectable in the field for your most common motors See jumper settings at the end of this manual When you power up the drive the current bank selected will be the one you are tuning in this session When done tuning that bank Save the parameters to the EEprom with the s command and then you can turn the drive off Testing a new motor for the first time Bank 0 When Bank 0 no jumpers is selected the Viper will limit the power to the motor by 60 to protect the drive from over current when setting up a new motor It s a good idea to put a 5 10 ohm 10 watt resistor in series with the motor power when testing only since if an encoder is n
6. a few encoder counts Also it would require a very high input step rate to make the motor spin fast We recommend a 1000 line differential encoder for most applications Encoders with less than 400 counts turn should be avoided The viper can handle up to 625Khz encoder frequency assuming good cableing A good source for encoders is US Digital com Page 3 The DC servo motor has a Permanent Magnet outside stator and a wire wound armature Carbon brushes connect the electrical power to the rotating armature They can either have 2 or 4 brushes A motor with 4 brushes gives a smoother motion The motor also acts as a generator while spinning and under deceleration can force power back into the drive A fast decelerating motor or a load pushing the motor can increase the power supply voltage Viper drives have at least a 25 voltage headroom and can handle moderate over voltage Mos Fet Bridge _ The Viper drive uses a can Mos Fet or an IGBT ch PWM wave bridge to drive the servo gi motor AA The signal is Pulse Width Modulation or PWM with a frequency of 20 000 HZ DC motor PAGE 4 Viper 75 95 Drive Connections Power Input Serial Main Program 222 Fuse kii i Step Dir Input i Fault and Current dah Warning Fault adjustment Encoder Motor Power Input Output Viper 100 200 Drive Connectors Main power 12 18 Input Main Vdc In Serial Fuse E Program s Step Dir
7. moved to one side for easier mounting in cabinets Page 7 Selecting a Powersupply Voltage Motors typically specify a maximum DC voltage and maximum RPM EG and MCG ID34002 servo motor has a max DC voltage of 90 volts and runs 5000 rpm at 90 volts These are maximum ratings however you can set the powersupply lower than this to run the motor slower In a motor the voltage determines the RPM and the current determines the Torque When the motor is running with no load the current is small As the load increases the motor draws more current from the power supply Current in motors are rated by Continuous stall current This is the maximum current the motor can take continuously without overheating You probably won t be running the motor this hard all the time so the power supply can be rated at a lower current maybe 60 of this value Most power supplys can output 1 5 times there rated power for a short time and since the average power used by the servo system is usually low you can usually use a power supply with a lower VA rating than total calculated power The Fuse in the Viper drive should be the value of the continuous stall current or slightly above to protect the motor The other current rating of the motor is the pulsed peak current This is the current that motor damage can occur if exceeded The Viper drives can output peak currents at 200 of their rated current for less than 1 second Setting a Safe Maximum RPM You
8. of current allowed to the motor and turning them CCW makes them trip at a lower current NOTE use a plastic or non metallic screw driver to adjust these pots to prevent shorts or electrical shock if the screwdriver touches the PCB board Adjusting the Current Limit and Trip To start adjust the both pots at about midpoint With the motor holding apply a twisting to the shaft to simulate an excessive load of the amount that you want to trip the drive Note Be careful not to cause excessive high current and damage motor or drive While holding the motor in this position adjust the trip pot CCW until the red LED lights The motor shaft may cycle slightly as the CPU reduces and holds the PWM cycle indicating current limiting Holding the red light on for 2 seconds will make the drive cut the power to the motor and flash the Fault light rapidly This is a fault trip condition To reset the drive disconnect the 12volt to the control side to Reset power to the drive to reset the trip fault Adjusting the Current Warning pot Do the same to adjust the Warning limit pot with less of a load on the motor The yellow LED is used to set this current Use a small load to activate the Warn setting The warn doesn t trip the drive but flashes slowly the Fault light and holds down the Stop output if the current stays high for more than 2 seconds When the load reduces the error goes away Set the Yellow LED to come on at a lower load than the
9. screws are 8 32 The size of the Fuse should be slightly above the motors continuous current rating The fuse is to protect the motor from burnout Note The small signal side will be grounded the to chassis ground by encoder connector 9 pin D type when mounted to a case Warning Voltages over 80 volts can be lethal Be sure to ground the motor frame when testing and have viper drive mounted in grounded chassis when testing PAGE 10 Viper 75 95 Power supply recommended layout Important Keep wires between Main capacitor and Viper Drive less than 8 20cm Motor Do Not put Breaker or Disconnect between Power Main capacitor and Viper Drive b 2 Malin Fuse o sil Oo ee NJ ea ey 7 120 WI 400V NAN D 25amp Vac o Bridge 4 PAN NG 2 Rectifier o G e sae es U ay See Main Capacitor Emergency Main Transformer Disconnect Discharge Resistor The viper 75 uses a single supply voltage The drive uses a voltage stepdown regulator to get its 5 voltage for cpu and encoder This can generate a lot of heat so the drive should be well heat sinked The main transformer voltage is to match motor voltage requirements DC volts AC voltage x 1 414 Keep the main DC power wires short typically 8 20cm or less This is necessary because the drive is switching a 20 Khz power signal to the motor This frequence is present on the incoming power wires and the longer they a
10. Viper DC servomotor drive Manual V2 0 1 Last edited Feb 15 2011 Full featured Industrial quality DC servodrive Viper 75 25 75 Volt 10 amp model Viper 95 25 95 Volt 12 amp model Viper 100B 25 100 Volt 20 amp model Viper 200B 50 170 Volt 20amp model New Viper 100F 25 100 Volt 30 amp model New Viper 200F 50 170 Volt 30 amp model 32 bit PID control with 16 bit RISC processor 300Khz Step rate on new F series Step Direction Control Feed forward command Warning output signals excessive motor load slow down Trip output signals drive has tripped Opto isolated power and control sections Onboard fuse protect motor and for safety 4X or 1X quadrature encoder counting Separate voltage regulator for encoder power 1 2 4 8 step multiplier or any size Settings are programmable by RS232 Replaceable Power Mos Fets and drivers Large main capacitor Very efficient cool running drive Stack able card type mounting Up to 4 motor configurations can be stored Jumper selectable motor rotation direction DISCLAIMER Larken Automation assumes no responsibility for any personal injury or damage caused by use of its products Only electrically qualified personal should attempt to install the Viper drive High voltage can be lethal and proper safety procedures must be followed Motors and drives should be properly grounded to prevent electrical shock Safety glasses should be worn si
11. ak Current The peak current is the absolte maximum momentary amount of current the motor can take for before damage to brushes or windings occur The rating thats important is the Continuous stall current This is the maximum continuous current the motor can take before windings overheat and destroy them selves The drive needs to know this rating to be able to protect the motor against heavy overloads If the drive sees this cuurent exceeded for more than 2 3 seconds it will shut down the drive and cause a overcurrent error error 6 When the drive see s very high current it automatically reduces the current to the continuous rating If this current stays for 2 3 seconds the drive shuts down It allows peak currents up to 45 amps under accelleration decel but reduces it quickly to the safe limit and holds it there To set the current first you need to know the Continuous Current rating stall of the motor The drive can t accept the actual number but you enter a lookup value from the table below EG to set the Viper 200 to 12 amps enter the command a61 Use the table below to get the correct value to enter in the Viper and enter it using the a command This value is used by the ADC converter on the PIC chip Viper 100 200F a value for Viper 95F a value for Amps V200 Amps V95 6 30 3 81 _ _ __ 14 71 18 91 11 168 22 112 24 122 26 132 28 142 30 153 Page 23 To reset the drive
12. cr gt V2 m Get motor encoder and step position m lt cr gt m0OFO s0OF1 hex result Other 0 Disable power to motor x Enable motor power Z Set defaults and save to EEprom s Save settings to EEprom Notes lt cr gt enter Only change Bank if you are entering data for banks other than the bank selected by the jumper for saving Page 30 Run the windows Hyper Terminal program from the Accessories group Create a New session using Comm1 9600 baud 8 1 N In the advanced tab set Flowcontrol to None If Hyper term isn t on your system then it can be installed from your windows cd rom or downloaded from the internet All commands are entered in lowercase and followed by a carriage return lt cr gt Example screen shot of Hyperterm pic HyperTerminal DER File Edit Yiew Call Transfer Help SER EERE EERE EE EEE EEE HHHH HHH HHH H H H H H H H H H HEHH HEHH EEE EEE EEE EEE EH LKR The Command shows the current settings The Kp is 575 Anew Kp of 600 is programmed using the command p650 The bank is saved Power is disconnected and the drive reset which shows LK R The Command shows the Kp was changed to 650 and stored in EEprom Page 31 Selecting Jumpers reserved for programming not on V75 95 Reverse Motor Parameter Bank _ Select Step multiplier ye Select Jumpers are used to select Parameter Bank Step multiplier and Motor direction Jum
13. e Loop Time parameter one unit at a time either way until the motor reduces its oscillation and disturbed responce becomes most dampened The range or the loop parameter is 1 8 Disturb the motor with an abrupt jog or bumping a pulley After this is set you shouldn t need to change this parameter The Loop parameter matches the response to the mass of the motor and load EG Very small motors may use a L setting of 1 2 Size 23 motors may use 2 3 or 4 Size 34 motors may use 3 4 or 5 Size 42 motors may use 4 8 etc The length mass of the lead screw of size of a pulley will effect the L setting as well 2 Increase KP 50 points at a time until the motor gets stiffer 3 Keep increasing KP until the motor starts to oscillate when disturbed bump the shaft or accelerate back and forth 4 Then increase KD until the motor is stable KD usually ends up about 2 times KP 5 The KI term is usually a very small value 2 20 since it adds to its self rapidly The KI should be set to zero until KP and KD have been adjusted 6 Save the parameters by using the s command Saving is disabled in bankO Parameters in banks 1 2 and 3 can be saved Note The power supply voltage also plays a part to the tuning For any given motor KP and KD will need to be less when the power supply voltage is high compared to if the voltage was lower This is because a certain gain produces a duty cycle and the actual voltage to the motor is t
14. gital or pulse train The encoder has 2 square wave outputs They are staggered at 90 deg This way one is leading the other when turning CW and then trailing the other when turning CCW Rotating disk These are Channel A and B The controller can tell which way the motor is turning by the A B sequence There may be an optional Index output also The index is Encoder Outputs not used by the Viper Ar LI LJ A differential encoder has 2 outputs for A channel and 2 outputs for B channel The second output is an inverted B version of the origional and is designed to drive a twisted pair cable to cancel noise Differential encoders are recommended for motors with cables longer than 4 6 feet Encoder Line count is the number of lines per turn With in the viper drive the line count is decoded 4 times finer quadrature so with a 1000 line encoder the viper drive sees 4000 counts turn This is not to increase machine resolution but to give the drive more counts to reduce error The Step Multiplier setting in the viper sets the ratio of incoming Step direction pulses from the control software to the 4X encoder counts So with a 1000 line encoder and a step multiplier of 4 you would have 1000 steps turn With a step multiplier of 8 you would have 500 steps turn With a step multiplier of 1 you would have 4000 steps turn but don t be fooled thinking your machine will be more accurate A servo system always runs with a error of at least
15. he power supply voltage duty cycle PAGE 18 Tuning Summary KP Sets the stiffness of the motor KD settles the oscillation and overshoot The Loop time needs to be matched to the motor and load early in the tuning when the KP and KD are at lower values but can be re adjusted at final tuning KI can be added at the end to improve low speed holding error The L setting should be set early on in tuning and matches the motors mass Other settings include Range Trip Feed Forward Encoder Limit settings There are 2 settings to signal that the following error is out of range The Range setting can be set to output a error warning to stop the cnc controller if the following error is to high This will hold down the Estop signal but not disable the Viper drive The Trip setting will disable the drive if exceeded and hold down the Estop to the cnc controller Zero ee Padi gh g k DN S i Range i warning N Y AASA eee 0 ih N N Trip a E X Fatal SA e Both Trip and Range are in quadrature counts lines x 4 so to set the Trip command to 3 4 of a turn of a 500 line encoder the setting would be 1500 This setting is designed to protect the drive and motor when an extreme out of range is detected The max setting allowed for the Trip command is 4000 PAGE 19 Feed Forward parameter With a Stepservo drive the faster the input step rate the larger the following error
16. ial programming and testing can be done with the drive just connected to Control power as shown below use main power on V75 V95 The serial cable needs to be connected for tuning using a windows PC running Hyperterm E J CONTROL PROGRAM 12 Volts MAIN POWER IN e Direction e and lt Step inputs J e Fault LED and Estop out Warn o Current o Limit VIPER Use this setup to test the encoder using the M command When power is first applied the m000 s0000 will display m Motor position s Step position Turning the motor one way should increase the encoder counter and the other way should decrease it into negative values Note this register is displayed in 16 bit Hex so negative starts from FFFF and gets smaller Also you can set the range command r to the number of motor counts of error before the drive faults and flashes the LED You can also set up a number of other parameters without having the motor power connected Get familiar with the drive before connecting the main motor power PAGE 17 Tuning the PID loop Note Be sure to have the motor mounted or clamp the motor to a table before tuning The motor can react very violently and cause damage or personal injury Note Remove the bank jumpers Bank 0 so the drive runs in current limited mode when checking the wiring on a motor for the first time Start with KP 100 KI 0 KD 200 and Loop 4 1 Adjust th
17. ing in shield Encoder Current Note Encoder current is limited to 75ma on the Viper 75 95 due to the internal voltage regulator dropping the Main voltage down to 5 volts Viper 100 200 maximum encoder current is 250 ma Viper 75 95 maximum encoder current is 75 ma PAGE 14 Encoder connections 5 volts out for encoder power Channel B input inverted Channel A input inverted Pin 8 N C Gnd Single Ended encoders When connecting a single ended encoder the unused input should be pulled to ground with a 2K ohm resistor 2000 ohm 1 4 watt Vv 1 a amp Ox ot 9 ka Gi d C Na NI 6 Single Ended Connections Terminating long cables A differential encoder is recommended for any cable longer than 6 feet 2 meters For very long cables it is sometimes necessary to put a terminator resistor across the differential pairs The resistor value is usually 150 ohms 1 4 watt A 0 05uF capacitor may be put in series with the resistor to reduce power consumption DE 2 A A B8 B 2 O O O O N Terminator resistors Page 15 Understanding PID control PID stands for Proportional Integral Derivative These are the 3 adjustable factors that make the controller able to keep the motor stable in the servo loop All factors are adjustable in magnitude by the user A servo works by constantly correcting the position error The error is the difference between the encoder position and the ste
18. male back lan ge luF 100k N Li Reset V75 TX out RX in Se Gnd Rs232 serial interface and V75 reset The RS232 programming cable is available from Larken Automation PAGE 12 Fault output for multiple Drives Fault Indicator 7A A o Flash out 470 O AA t 8 vols out o Drive A Stop out O Breakout Board qe o TY Drive B e Estop Input O OT E Stop o Drive C N Otype o gt es Active Low on fault BOB should share common Negative or Gnd with Viper ae Po ons Viper can be grounded by mounting encoder connector in a chassis or by grounding the N EG wire of 12V power Page 13 Motor Encoder and Power connections DC Servo motor Encoder yo N Ground shield fo motor but not controller Encoder A EncoderA Encoder B EncoderB kh ao 0 o o NA 2 o O 5 Volts cd Encoder Input Armature Looking at drive Power Use twisted pair network cable for encoder cable Stranded wire not solid Note Diagram shown for a differential encoder For a single ended encoder use just one connection per channel Use stranded twisted pair cable for encoder wire Use shielded wire if available Connect the shield on one end only to avoid current flow
19. must decide what is the maximum RPM that you want the motor to run on your machine incase of a possible drive failure This may put full power supply voltage to the motor and case a dangerous situation As a rule set your power supply voltage to only about 10 20 higher than what you would need for your maximum rapid feed rate Running the motors at a lower voltage also reduces heat in the motor and drive and increases motor and brush life PAGE 8 Viper 100 200 Power supply recommended layout Important Keep wires between Main capacitor and Viper Drive less than 8 20cm Motor Do Not put Breaker or Disconnect between Power Main capacitor and Viper Drive Main Fuse lt s a a sae amp 120 Ni 400V 4 O 25amp 20 000u Vac Cy e Bridge Ne P a Rectifier Np en e a E Dp Emergency Main Transformer Main Capacitor Disconnect 1Amp Fuse a ls NIC qy CH 100V eo aT apan 1 5amp WES E NSg7 mle E tu 18 VDC 2 VAC Control side power The viper 200 uses Isolated Power and small signal sections to eliminate ground problems associated with high power controls This increases reliability and reduces ground and noise problems The main transformer voltage is to match motor voltage requirements DC volts AC voltage x 1 414 Keep the main DC power wires shor
20. nce electrical components can explode causing injury or blindness Copyright Notice No part of this publication may be reproduced mechanically or electronically in any form without the prior written permission of Larken Automation Inc Firmware on the Viper drive is property of Larken Automation and reverse engineering or disassembly of the code is strictly forbidden The information in this manual is for informational use only is subject to change without notice and should not be construed as a commitment by Larken Larken assumes no responsibility or liability for any errors or inaccuracies that may appear in this document Viper Starcam and Starcnc are registered trademarks of Larken Automation Inc 2006 Larken Automation Inc Tech support Contact Larken Automation Inc 5350 Canotek Unit 13 Ottawa Ontario Canada K1J 9E1 Ph 613 746 5685 Fax 613 746 6451 E Mail Larken storm ca Website www Viperservo com Website www LarkenCNC com PAGE 2 DC Servo Motor Basics The DC servo motor has an optical encoder that provides feedback to the controller This typically can have from 100 5000 counts per turn The most popular type of encoder is the optical encoder which consists of a rotating disk a light source and a 2 photodetectors light sensor The disk which is mounted on the rotating shaft has many slots in it As the disk rotates these slots interrupt the light emitted onto the photodetector generating a di
21. on main power Encoder Trip t setting Current Trip exceeded motor current Encoder fail no pulses Short circuit protection CONOR WN Errors can be reset by turning off the power 12volts on V200 or using the x command through the terminal The Under voltage error will stop when the viper 200 sees the power come back on The drive will soft start after a few seconds But the Error value 64 is kept stored in the error register in the drive This alows you to poll the drive to see if an under voltage happened while the drive was running In parameter display 2 seen by pressing 2 lt cr gt in terminal the Er line has 2 parameters The first parameter is the error register which holds a code the same as the flash count The second number is the Bit Coded Live Error Flags This is a binary number showing current read errors This can show more than one error EG Encoder trip and under volt Bit O Trip current Bit 1 warn current Bit 2 Encoder range Bit 3 Encoder Trip Bit 4 Under voltage Bit 5 Encoder fail Bit 6 Bit 7 Short circuit failt EG Er04 11 04 Under voltage 11 current trip and undervolts Page 25 Adjusting Current limit and Current warning For older Viper A amp B series with trim pots There are two trim pots on the Viper The one closest to the edge of the board is the Current Trip setting and the other is the Current Warning setting Turning these pots potentiometers CW increases the amount
22. ot wired correctly the motor can violently oscillate possibly causing drive damage by excessive current Remove the resistor after the wiring is confirmed correct LL CONTROL 12 Volts PROGRAM MAIN POWER IN Direction and Step inputs gt e Fault LED and Estop out e e Warn ol ENCODER MOTOR OUT Current Limit VIPER E is fo ite You can also set the PWM Clip limit command c to 200 to limit the maximum power to the motor Its range is 100 450 450 90 PWM You can use Bank 0 to test and program parameters for the motor then write them down and enter them in an other bank Only Bank 0 is current limited The default KP KI and KD are set to low values in this bank for testing motors Note The motor should hold when power is applied if correctly wired Page 21 If the Motor runs away when turned on If when setting up the motor for the 1 time and it runs on when power is applied Reverse the power connections to the motor Or reverse encoder channels A B Note The limit resistor needs to only be there for setup and should be removed before final tuning Use the Clip command to limit power to the motor while tuning Page 22 Setting Motor Current on New Viper F series with advanced current control The Viper can control the current to the motor to protect it from burnout Motors are rates with 2 ratings Continuous Stall current and Pe
23. p dir counter The Proportional term KP directly outputs voltage to the motor in opposite proportion to the error By its self though the motor will just bounce back and forth in oscillation as this is factor increased The Derivative term KD keeps the loop stable by comparing the latest error amount to the last error amount If it sees the error getting worse over the last 2 loops then it increases the power in the opposite direction to correct If it sees the error getting less then it reduces the correcting power to the motor The Integral term K is a correcting factor that helps correct a positioning error by increasing the correction higher as time goes by EG if a load was hard to move one way and caused a steady error to the left the Integral would push harder and harder to the right on each loop of the servo timing building up as time goes by As the load corrected the servo would reduce pushing to the right Servo Loop The controller runs a software loop which reads the encoder and calculates a new output power and polarity to the motors thousands of times a second LOOP Read encoder motor position Read commanded position from step and direction input Subtract the two to get the error Calculate KP error proportional result Calculate KI Integral error sum Integral result Calculate KD error T error T 1 Derivative result Add all 3 results to create the output correction value Convert to a PWM d
24. pers are read on powerup Reset power to read moved jumpers Reverse motor jumper allows changing motor to run CCW or CW Parameter Bank Select ome O 0 GK Cor L 6 6 6 6 6 6 GA DR e O Cm Bank O lest mode Bank Bank2 Bank3 Step Multiplier Select O O OQO O O FO EN HEN E CY S an EN N LJ NA er AG NI A J Ka one ose Cy ene 6 6 6 6 6 6 Hogamable 4X multipli 6X multiplier 10X multiplier multiplier pant p p PAGE 32 Component Data Parts supply Available from Digikey www Digikey com 1 800 344 4539 Fuse 5 7 5 10 15 or 20 amp automotive type Select the fuse amperage to protect motor winding or machine from damage incase of drive failure Power Mosfets for Viper 100 200 IRFB 4232 PBF 56 amp 250volt mosfet Mosfet driver chips IR 2104 8 pin dip Connectors Output and motor power Viper 100s Digikey Part Description 277 1011 ND Pheonix 2 pin plug green power 10 amp Output and motor power Viper 200 277 1463 ND Pheonix 2 pin plug green power 20 amp Small connectors Digikey Part Description WM2200 ND tiny Crimp term 1 for block WM2000 ND Housing 2 Pin 1 for 15 volt power WM2001 ND Housing 3 Pin 1 for fault output WM2002 ND Housing 4 Pin 1 for step direction WM2003 ND Housing 5 Pin 1 for RS232 A Crimping tool for 1
25. re the more inductance there is This can cause voltage spikes to exceed ratings of the mosfets and capacitors reducing component life The Viper 75 CPU will stay active until its voltage goes below 3 5 volts This means that when you turn off the power supply and turn it back on before the voltage has decayed below 2 3 volts the viper may not have reset The Discharge Resistor is required to drain the power supply faster to allow the Viper 75 to get below its 2 volt reset voltage Also the Viper 75 has a Brown out Voltage Fault to protect the mosfets incase the power supply goes below 15 volts This causes the error light to go on steady Note The viper 75 will be grounded the to chassis ground by encoder connector 9 pin D type when mounted to a case This is recommended to reduce noise in the encoder cables The negative power supply input is common to the encoder connector case as well Page 11 Viper Interface connections O 5V Step and Direction interface Opto lsolator on Viper R 330 ohm Direction 5 volts 5 volts Step O Note This was incorrectly labeled in version 1 6 V Q AN hAm Flash out Warning and Fault output 77 Open collector outputs 5 volt output from 5 volts out Active Low on fault Negative is common with Input power Gnd Stop out Viper PS 25 mA max Db9 Fe
26. red This can be set to indicate the machine is under excessive load cause by a dull cutter or jamming condition etc The Software error range setting causes the Fault light to flash very slowly and holds down the Stop output as well if the motor goes out of range for more that 2 seconds When the motor error is less than the range setting the error goes away The Viper has 2 output signals One is to power a flashing LED on the front panel of the controller and the other should be connected to your Estop signal to stop the motion commands These are open collector outputs and can be parallel connected to multiple Viper drives Page 26 When an error is flashed the Viper will hold down the Estop signal until the error is removed You can add a Fault override switch normally closed in this estop line to allow the operator to jog the machine while holding the switch to recover from a warning error LED flashing errors Older Viper A amp B series Slow flash Motor is out of position range motor power still enabled Medium flash Warn current reached motor power still enabled Fast flash Current trip reached and Output power has been disabled Very fast Encoder trip Exceeded T setting Page 27 Adjusting Balance or Motor Offset If the motor has a constant load in one direction such as lifting a load then there may be more of an error in one direction than the other The balance command lets you preset a PWM value other
27. t typically 8 20cm or less This is necessary because the drive is switching a 20 Khz power signal to the motor This frequence is present on the incoming power wires and the longer they are the more inductance there is This can cause voltage spikes to exceed ratings of the mosfets and capacitors reducing component life Page 9 Viper 100 200 Power supply recommended layout continued Do not put a breaker or disconnect between main capacitor and drive This can cause a extremely high in rush current to the drive when the contact is closed This is because the energized main capacitor will discharge into the unpowered drive and can damage connectors and PCB traces Put your disconnects before the transformer to give a softer powerup Also the disconnect should shut down both 12volt and motor power together to prevent the motor from jumping back to position if the 12 volt encoder and control power was kept active The 12volt can be disconnected while leaving the main power on however This can be used to reset the drive The 12volt may be powered from the main transformer as a 2 winding but must be isolated The high power side of the viper is isolated from ground and small signal side It is best to keep this side isolated The heatsink is isolated from the viper circuit The side mount Viper drive is designed to be mounted vertically with its encoder and motor connectors through the bach of the cabinet The mounting
28. than Zero as its neutral so even with zero error the motor will be applying torque in that direction To adjust this setting disconnect the encoder and step inputs oo k ONTRO reel ag PROGRAM MAIN POWER IN e Direction and lt Step inputs Oo Fault LED and kd Estop out e Warn ol Current Limit VIPER ga Without the encoder connected and with no step input there will be no error This will make the drive output a zero PWM value 50 effective at the motor Change the b command until the load is neutralized and the motor stops turning under load Values of up to 100 are allowed but shouldnt be exceeded since the motor is always under load and may overheat Use the s command to save the setting A mechanical counter balance to the machine should be added if the offset is high to prevent motor heating PAGE 28 Friction Compensation On systems where there is a lot of friction or stiction the motor may no start to turn at all until it hits certain level of power So the motor may not start the load until the PWM is al least 10 The h command allows you to set the lowest PWM value which is normally zero To tune this command connect the drive with the encoder disconnected You will need to have a Step dir source that can output 1 pulse at a time to create an error which causes the PWM to gradually increase Lh _ b
29. uty cycle and output to motor JUMP to LOOP START The loops per second is an other programable setting in the Viper drive This has a big effect in matching the mechanical reaction time of the motor Generally the heavier the motor armature the slower the loop timing needed Note a motor can only respond so fast to changes in position correction Some drive manufacturers claim very high loop times of millions of loops per second A typical motor can only change its acceleration deceleration velocity at a rate of a few hundreds of a second Also if the PWM frequency is 20 000 cycles per second The loop time has to be slower than the PWM PAGE 16 Programming the Viper Drive The Viper is programmed by connecting to a PC using the serial RS232 port A cable can be made as described above More info and the viper command set is at the end of this document Run the windows Hyper Terminal program from the Accessories group Create a New session using Comm1 9600 baud 8 1 N Note on software version 3 0 or greater Baudrate is 38400 baud This is on drives that flash errors as acount not by speed All new Fseries drives run at 38400 baud after Jan 2011 All commands are entered in lowercase and followed by a carriage return lt cr gt Note The viper command set is at the end of this document When you apply power to the viper the letters LKR should appear on the PC screen Pressing lt enter gt should return a prompt Init
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