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Stepper Motors Only Turn in the + Direction (no -) Generation 6

Posted by An Original Name 
Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 01:45AM
Hello all,

Some of you may have remembered me from last year when I was working on building a RepRap last summer. Well, after being busy with college all year I'm ready to start working on it again this summer and will, hopefully, get it working very soon. There are only a couple hitches still in the way, one of which I will address in this topic.

From the topic title, I am using Generation 6 electronics (the first batch I believe) to control the RepRap. I am currently using Repnapper to test all things to ensure they are working properly. Through testing, however, some odd things are happening:

1] The stepper motors will not turn in the - direction. Only the + direction. This includes the extruder motor.
2] When pressing the "home" button, the motors continue even past the endstops and simply stop when they torque out due to actually pushing a physical part of the machine against another physical part (I know... it makes me grind my teeth just thinking about how damaging this may be).

At any rate, the Gen6 electronics came with their own opto endstops that were already put into connectors. It would be a shame if they shipped me faulty endstops or something. I read somewhere that when an opto endstop is not plugged in, the RepRap will only go in the + direction, which seems a bit suspicious to me, relating to my situation.

The steppers I'm using are Lin Engineering bipolar 4 connector steppers sourced from altronics.

Any help would be appreciated. The following are pictures showing my stepper wiring, etc.
Instructions on board indicating to which pin each coil belongs:
[imageshack.us]
If the image is too small, it basically says:
Pin 1: A+
Pin 2: A-
Pin 3: B+
Pin 4: B-

Lin Engineering guide for stepper wiring (note that I'm using the topmost 4 wire variant: red, blue, green, black):

Picture of the connector I'm using for the steppers (note that the Lin blue was soldered into the white on these wires because the wiring I'm using is red, black, green, white):
[imageshack.us]
Closeup of connector attached to board. Pin 1 is on the left:
[imageshack.us]
Overview of whole board:
[imageshack.us]

Has anyone else gotten this problem who could help me out? I feel like I wouldn't be the only one to have this happen to someone. At any rate, any help at all from anyone is highly appreciated.

Thanks,
An Original Name

Edited 2 time(s). Last edit at 05/08/2012 01:46AM by An Original Name.
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 02:30AM
Yes, if your motors only go in the + direction then 99.9% of the time it has to do with the end stops.
I am not familiar with the Gen6, does it have BOTH MAX and MIN end stops?
Are they plugged into the MIN connector?
Are they plugged in correctly?
Plugging the opto end stops in the wrong way can destroy them.
You may need to invert the end stops in the firmware.


Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 03:09AM
The molex connectors are keyed so they cannot be inserted the wrong way. There is only one endstop per axis. Does this mean they sent me faulty hardware?
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 08:21AM
If it only goes in the + direction it shouldn't hit the end stops because they should be at the - end.


[www.hydraraptor.blogspot.com]
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 11:50AM
Assuming the wiring and switches are good It's likely the Firmware is incorrectly configured for the endstops, i.e. you need to invert the expected signal.
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 02:58PM
Nophead:
Yes, they are all moving in the direction of the endstops. This means that the stepper connectors need to be flipped around, correct?

*edit*
The steppers are now moving in the correct direction.

Polygon:
I haven't done much messing with the firmware. I have Arduino and Sanguino installed, though. Any pointers on where to start with modifying the code?

*edit 2*
After some searching on the RepRap wiki, I found this, which gives a list of all possible options for endstops with gen6:
[reprap.org]
Judging from the wiring, the endstops that came with mine are the "Non-inverting optos."

Edited 2 time(s). Last edit at 05/08/2012 03:04PM by An Original Name.
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 03:49PM
Do you know what firmware is installed?
With most firmwares it's a question of downloading the Arduino tools, downloading the source code for the firmware and making changes in the configuration.h file.
You can reverse the motors either by swapping the wiring around or just by inverting the direction pins in the firmware configuration.
Re: Stepper Motors Only Turn in the + Direction (no -) Generation 6
May 08, 2012 04:22PM
Alright, I think I got it working. Thanks for everyone's help. For reference, I downloaded the firmware here: [reprap.org]
and made sure that these three defines in the configuration.h file were set to false:
Quote

#define X_ENDSTOP_INVERTING false
#define Y_ENDSTOP_INVERTING false
#define Z_ENDSTOP_INVERTING false
Apparently the old firmware that was uploaded to my board had them set to true (which was for the older endstops that Camiel supplied). However, my endstops were newer and he started using non-inverting endstops. Looks like I'm one step closer to getting a printed object! Exciting!
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