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Author Topic: Stepper motor working in 1 direction only!  (Read 9412 times)

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Stepper motor working in 1 direction only!
« on: March 15, 2011, 07:32:58 AM »
Hi All, new to MACH3 & CNC control in general, so hoping I've just got something silly wrong here!

I've got a stepper motor (Bipolar) connected to a Parker XL25 driver, connected to my PC & MACH3.

The driver can operate in 2 modes, Step/Direction, or Step+/Step- mode.

wired for step/direction, I have ports 1&2 on the LPT connected to the corresponding step/dir ports on the driver, but although the motor powers on I get no motion.

Someone suggested that by switching to Step+/Step- mode (there is a DIP switch on the driver to do this) and just wiring the Step- & Dir - pins on the driver together it would work.
Now I get motion in one direction only (presumably caused by the inputs on the Step+ & Dir+ pins, but lacking any input on the Step- & Dir - pins)
Is it possible to configure MACH3 to operate in this Step+/Step- mode, or any trick to get the Step/Dir mode working?

Many thanks for any help - much appreciated!

Dave.

Offline Tweakie.CNC

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Re: Stepper motor working in 1 direction only!
« Reply #1 on: March 15, 2011, 09:09:35 AM »
Hi David,

Welcome to the forum.
I have not actually used the XL25 I am just going by the manual but it would seem that the XL25 inputs should be connected;
Pin 1 to computer LPT pin 2
Pin 2 to computer LPT pin 3
Pin 6 GND
Pin 7 GND
And mach configured (active high) something similar to attachment (it is not usual to use Pin1 of the computer LPT port for step and direction signals)

Now this should work but it is not the preferred way to do it because the computer’s LPT port can sink more current than it can source. Either (a) connect Pins 1 and 2 of the XL25 through current limiting resistors to +5 volts and use pins 6 and 7 as active low inputs from the LPT port pins 2 and 3 or (b) use an active breakout board which can provide the TTL level signals to the XL25 without loading the LPT parallel port.

Tweakie.
« Last Edit: March 15, 2011, 09:23:15 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Hood

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Re: Stepper motor working in 1 direction only!
« Reply #2 on: March 15, 2011, 09:35:09 AM »
Personally I would make up (or you could buy) a line driver to change the Step/Dir single ended signals out of the PP into Differential.
Hood
Re: Stepper motor working in 1 direction only!
« Reply #3 on: March 15, 2011, 09:42:56 AM »
Thanks for the replies!
Will have a go at shifting the pin assignments to 2&3, though should it make much difference if I've specified pins 1&2 in the outputs of MACH3?

When you say pins 6&7 to GND, is that simply left disconnected, or is there a specific place/pin I should attach those wires to?
Sorry if the questions sound stupid, this electrickery is all new to me!

Many thanks,
Dave.

Offline Tweakie.CNC

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Re: Stepper motor working in 1 direction only!
« Reply #4 on: March 15, 2011, 09:50:21 AM »
Dave,

Pins 6 & 7 are the low end of the opto isolator circuits and they should be connected to Ground or 0 Volts (pins 18-25 of the LPT port if you are not using a breakout board or 0 Volts of the active breakout board supply).

Tweakie.
« Last Edit: March 15, 2011, 09:56:31 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Stepper motor working in 1 direction only!
« Reply #5 on: March 15, 2011, 10:02:46 AM »
Thanks for the edit, just had to google that one ;-)

Will have a go at that now & see how it goes!

Cheers,
Dave.
Re: Stepper motor working in 1 direction only!
« Reply #6 on: March 15, 2011, 11:18:06 AM »
Many thanks for the help guys, thats working perfectly now!
Re: Stepper motor working in 1 direction only!
« Reply #7 on: March 26, 2015, 12:39:57 PM »
Hi, could someone help me ? i have only started cnc a few months ago and have made a controller which worked fine the stepper driver is Chinese (24V-50Vdc) actual 48Vdc.

I have now made a second but i am having some problems as below.

Steppers erratic movement and will only run one way, motor step/direction is set up as my previous driver
X - Step pin 2, dir pin 3 and so on for 3 axes.  No home/limits set, no e-stop set by unchecking the input ports and pins set up correctly as is in Mach ports & Pins settup.

My stepper drivers are Chinese which i have used before (24V-50Vdc)
The input voltage to these however is reading 24Vdc. I am wondering if this the marginal voltage is the problem.

Any help will do please, thanks

Offline Tweakie.CNC

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Re: Stepper motor working in 1 direction only!
« Reply #8 on: March 26, 2015, 01:28:41 PM »
Hi, could someone help me ? i have only started cnc a few months ago and have made a controller which worked fine the stepper driver is Chinese (24V-50Vdc) actual 48Vdc.

I have now made a second but i am having some problems as below.

Steppers erratic movement and will only run one way, motor step/direction is set up as my previous driver
X - Step pin 2, dir pin 3 and so on for 3 axes.  No home/limits set, no e-stop set by unchecking the input ports and pins set up correctly as is in Mach ports & Pins settup.

My stepper drivers are Chinese which i have used before (24V-50Vdc)
The input voltage to these however is reading 24Vdc. I am wondering if this the marginal voltage is the problem.

Any help will do please, thanks


What is the maker and part number of your stepper drivers ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.