Stepper Motors not moving in negative direction

Hii
I am trying to create a reprap prusa mendel and am using Nema 17 stepper motors.
When i connected the motors to the RAMPS 1.4 board and tried to test them using pronterface, the motors are moving only in the positive direction that too randomly.
I am new to electronics and have no idea about what wrong i am doing.

Please help me out.
Thanx in advance..

Marlin protects the motor to cross the absolute zero. To easyly reverse the motor, flip its connector 180°.

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When it moves is it smooth or noisy and rough? If it's noisy and rough you've got the motor connections to the driver board wrong or the driver is bad.

@Zavashier thank you for your reply but flipping the connectors, the motors don't even rotate in one direction.
Moreover, its not about crossing the absolute zero, even after rotating in a positive direction it doesn't even turn in the other direction to reach zero i.e it doesn't even turn in the opposite direction.
Is there any other way to fix it??..?

@the_digital_dentist Thanks for your reply.
The motor runs smooth but it vibrates a little while rotating.
Is there something else that I am doing wrong??.?

Quote
Harshhb101
@the_digital_dentist Thanks for your reply.
The motor runs smooth but it vibrates a little while rotating.
Is there something else that I am doing wrong??.?

This is typically caused by incorrect Endstop configuration Check your endstops? you can tell the status of them with the M119 command if any are triggered then the motors will only move in the direction that the firmware thinks is away from them (You may need toinvert the logic of them in the firmware) motor's not moving smoothly could be the driving current from your Stepper drivers is set wrong.

HTH

Doug

ps I assume your using Marlin if so sorry but I can't help with it as I am not to familiar with it (I Use Repetier)

They will ususally go in only one direction if you haven't "homed" them to their endstops.
Are your endstops setup and configured properly?

Steve

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