Driving two DC motors(12V,5A) with the Polulu Dual VNH2SP30

first excuse me for my wrong English. i’m a french speaker. i’m trying to use the Polulu Dual VNH2SP30 to drive 2 DC motors, but it doesn’t work.

  • these are the caracteristics of my motors: motors supply voltage: 12 Vcc, nominal consumption: 4 à 5A
  • caracteristics of the battery that i have connected to the VIN of the dual VNH2SP30: capacity 5Ah, nominal voltage12V
  • I use the NI USB 6001 card of NATIONAL INSTRUEMENT to send the PWM in my dual VNH2SP30 and to activate the differents pins.
    the caracteristics of my card are:
    resolution 14-bit
    output range ±10 V
    maximum update rate 5 kS/s simultaneous per channel, hardwaretimed
    AO FIFO 2,047 samples
    trigger sources Software, PFI 0, PFI 1
    output current drive ±5 mA
    chort circuit current ±11 mA
    slew rate 3 V/μs
    output impedance 0.2 Ω

I have already use this NI USB card with the Pololu - TB6612FNG to drive 2 DC motors 6V, 70 mA and te system had worked very well. i don’t no why my system doesn’t work this time. i don’t know if it is the supply voltage of my battery which is too low for my motors; or if it is the output current of NI USB card which is too low. i know that the Polulu Dual VNH2SP30 can work with an ARDuino card and i think that an arduino card has the same caracteristic as the card that i use.
could you help me please


I am not familiar with the NI USB 6001, but I noticed that you listed the output range as ±10V; please note that the VNH2SP30 accepts logic signals from 0-5V.

How are you powering the Dual VNH2SP30 Motor Driver Carrier? Are you connecting 5V to the “+5 V (IN)” pin? You might also double check that you have a common ground between the two devices.


thank you for your answer.
yes my NI card has a +5V output. and i have connected the “+5V V(IN)” pin of the VNH2SP30 to this output. this is how i have made all my connections.

power connections:
out 1a--------> motor1 +
out 1b--------> motor 1-
GND----------> Gnd of my 12v battery
VIN-----------> + of my 12v battery
out 2a--------> motor 2 +
out 2b--------> motor 2 -

control connections:
1diag/en, 1ina, 1inb, 1pwm-------->Outputs of my NI card
gnd--------> gnd of my NI card
+5V V(IN)-------->+5v of my NI card
2diag/en, 2ina, 2inb, 2pwm-------->outputs of my NI card

The connections you listed should be fine. Can you describe more about what is happening? What kind of behavior are you getting from the VNH2SP30? You might try simplifying it by trying to drive one motor before adding the second. What signals are you sending to each pin (1DIAG/EN, 1INA, 1INB, 1PWM)? Also, if you have an oscilloscope, you might try checking those signals to make sure they match what you expect them to be.


i try with one motor and with a simple led (by replacing the motor by the led), but it doesn’t work. when i try with the motor i hear a noise like “kak kak kak kak”. and when i try with a led, the led doesn’t light. i don’t have an oscilloscope, but i have a multimeter. when i measure the voltage on the PWM pins, i have 5v; and the voltage at the motor pins give me 2mv when i was expected at least 5v. the pwm and the orders signals that i send to my driver are the same that i sent when i was driving the Pololu - TB6612FNG and it has worked very well. i don’t know if it is the frequence of the pwm that i send which cause problem. what is the frequence to send to the VNH2SP30 to drive a 12v motor? but i think that if the frequence of my pwm was too low for my motors, it will be enough to light a led. so i don’t understand what is the problem. If it is the driver which is failed, i don’t understand why i hear the “kak kak kak kak” noise when i connect my motors.

Thank you for the additional information. There is not a specific PWM frequency for using the VNH2SP30 to drive a motor with a particular voltage rating. According to the datasheet, it should work with PWM frequencies between 0kHz and 20kHz, so I do not expect that to be the problem. We generally recommend using higher PWM frequencies (above 20kHz) to eliminate audible noise from the motor; however, since the VNH2SP30 is only rated for up to 20kHz, I would recommend using close to 20kHz if you have it available. Could you post pictures of your system that show all of your connections? Also, have you tested your motor by powering it directly from your battery to make sure it works properly?


thank you for your reply. yes my motors are ok. I have already tested them. I try to join a picture to my post but it doesn’t work. sorry. But my conections are made exactly as i described them in my last post. I were almost sure that it was not a problem of frequence because my VNH2SP30 doens’t work even only with a led. I read in others forums that the VNH2SP30 is sometimes delivered with failed capacitor, so i don’t know. i think i will buy another dirver for my motors.

We test all of our boards before they ship and are not aware of any recurring problem with the capacitors, but they are outside the reverse voltage protection circuit and can be damaged if power is connected backwards. Can you link to some of the forum threads you mentioned?

I am sorry you had trouble uploading your pictures to our forum. It sounds like you might not be interested in troubleshooting the VNH2SP30 carrier any further right now, but if you change your mind later and want to continue, you might try hosting your pictures on an image hosting website (like http://photobucket.com/)and posting links to it here.


thank you. this is the link to view pictures of my system. I wish the link works!

s610.photobucket.com/user/Fabiol … t=3&page=1

so are you seeing any problems in my systems??

Thank you for posting the pictures. I do not see anything obviously wrong from your pictures; however it is very hard to follow all of the wiring. Could you measure the voltages of the 1DIAG/EN, 1INA, 1INB, and 1PWM pins and also confirm that the voltage on the +5V (IN) pin is 5V?


Halo. these are the differents measurements of the voltages:

  • on 1DIAG/EN i have 4.3v
  • on 1INA i have 4.2v
  • on 1INB i have 0v
  • on 1PWM pins i have 5v
  • and on the +5V (IN) pin i have 5V.

thank you

Could you try disconnecting the control lines from your NI board and just tie the pins high and low using the 5V and ground pins of your NI board? You can leave 1DIAG/EN disconnected since it is pulled up on the VNH2SP30 board and connect the other pins as follows:

1INA to 5V
1INB to ground
1PWM to 5V
5V (IN) to 5V
GND to ground

Also, you can leave all of the motor channel 2 pins disconnected for now.


i have already try this before when i was testing my VNH2SP30, but it hadn’t worked. i am using a new driver for my motors now, the " Contrôleur de Moteur 13A, 5-28V Pour Arduino, Code de Produit : RB-Rop-01 par Robot Power " and my system works very well. i have concluded that Robotshop delivered a failed VNH2SP30 to me and i am very dispointed because there is no garantee of the manufacturer in this polulu product.

I am sorry to hear you have moved on, but that is of course your choice. I do not think your conclusion that you received a defective unit is valid. We do test every unit before it ships, and it would be especially unusual for both of the drivers on there to fail on their own. Feel free to let us know if you want to continue troubleshooting.