Questions about steppers and drivers

Questions, Suggestions, Tips, Etc

Re: Questions about steppers and drivers

Postby tylerv » Sat Apr 02, 2011 4:52 pm

It would be cool to have the motor drivers removable in case one dies. It would probably be pretty easy with these two headers: Break Away Female Headers and Break Away Headers - Straight
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Re: Questions about steppers and drivers

Postby bdring » Sat Apr 02, 2011 5:13 pm

That was the plan. Technically those contacts are usually rated for 1 amp, so it would optional, but I personally would use it.
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Suggestion

Postby twehr » Sun Apr 03, 2011 12:27 pm

bdring wrote:If anyone notices an error or has suggestions, please let me know.


I had planned to install both the original interface board for use with Mach 3 and the DSP controller. One factor that stopped me from using the interface board was that I did not have a good way to deal with the PWM from the controller. I would have had to choose between the controller's PWM or the 2.x's front panel pot. Since the input to the interface is through the DB9 connector, I would need dual connectors that I would manually swap out. (Or, I suppose I could have added a switch that chooses the correct power control source before getting to the DB9. Hadn't thought of that till now.)

The ideal solution would involve a manual switch, located on the 2.x's control panel that would allow selection of either the control panel pot (via the DB9) or the PWM (taken from an unused output of the DB25 to be directed to the laser PS In connector. With this configuration, a person could do either of the following:
1. To use Mach3/EMC, connect parallel cable from computer to laser and select Front Panel as power control source.
2. To use DSP, connect parallel cable from the DSP controller/DSP control panel (in a separate box configured with a parallel port connector and select DSP (or PWM) as the control source.

Either way, there are no internal connections to change - just plug in the correct controller (Computer or DSP) and flip a switch.

Or if I were really lazy, I would ask you to do the above AND to have two DB25 inputs on your interface board, one for Mach and one for DSP with the 25 lines switched like an A/B box. :mrgreen:
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Re: Questions about steppers and drivers

Postby bdring » Sun Apr 03, 2011 12:53 pm

Good idea, I will add something for PWM power support. Can you take a picture of your setup and maybe a rough schematic? Is the PWM on the DSP 5V or 3.3V?
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Re: Questions about steppers and drivers

Postby twehr » Sun Apr 03, 2011 1:09 pm

bdring wrote:Good idea, I will add something for PWM power support. Can you take a picture of your setup and maybe a rough schematic? Is the PWM on the DSP 5V or 3.3V?


Here is the typical connections for the DSP (this is version 1.x but the current version is virtually identical except uses a single input voltage between 12-36v). The PWM signal is 5v.

My plan would be to build an adapter board to take all lines from the DSP and map to a db25 (more or less opposite of what you are doing). Then I can just run a parallel cable from the DSP adapter to the laser interface board. I have everything wired directly now. And that works well and is no more trouble than wiring your interface board directly to the drives, laser, etc. The only reason for doing this is to be able to swap out controllers at will (Mach3/ECM, DSP, Retina). All should work through your "universal" interface board.

If you need further info, let me know.

DSP TYPICAL MINIMUM OPERATIONAL CONNECTIONS1.pdf
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Re: Questions about steppers and drivers

Postby bdring » Sun Apr 03, 2011 3:18 pm

The FSE controller uses pin 15 for power control which is an input on the parallel port. I think I need to have it be a jumper selected pin and a switch controlled PWM/Pot feature.
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Update Pololu Interface board

Postby bdring » Sun Apr 03, 2011 5:25 pm

Here is an updated version. This adds features to switch between Pot based power control and PWM based control. A remotely located switch is used to energized a relay to switch to PWM control. I used a relay because I did not want to run the PWM signal all over the place. This keeps a short path. PWM comes in through the 25 pin D connector. It can come in on pin 15 or 14. Last I checked, FSE uses pin 15, which is not an output on a parallel port, so you can also use 14 which is a parallel port output pin.

pololu_intfc_rev_2.pdf
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Re: Questions about steppers and drivers

Postby twehr » Sun Apr 03, 2011 7:16 pm

Now if you really want to get fancy...

Add a 4th controller for the rotary axis, and a switch that feeds the y signals to tha y axis or the rotary. No more swapping cables :idea:
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Re: Questions about steppers and drivers

Postby cpdude » Sun Apr 03, 2011 8:24 pm

Bart,

Per this pinout (http://www.fullspectrumengineering.com/laser%20connection.html) isn't FSE using pin 17? Maybe I'm missing something. :?

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Re: Questions about steppers and drivers

Postby bdring » Sun Apr 03, 2011 8:30 pm

According to Henry, that is the enable pin. Under vector control there is also a PWM on pin 15.
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