Hello,

I am putting together a new mach3 system for a cnc router.  I am confused as to how the stepper driver gets the stepping signals.

First a little background.  The three stepper motors I have are Nema 42 which came off of a piece of packaging machinery.  That machinery was run by an industrial computer.  I have the schematics for the original packing machine.  In the original schematics it shows a +5vdc signal on the step input of the driver, and a -5vdc signal on the direction input of the driver.  This changes throughout the schematic.  I am assuming this is for clockwise and counterclockwise movement. 

I am trying to run these drives through my parallel port on my computer, but I don't understand the positive and negative situation.  I was under the impression that if you wanted to step forward, only the step input got the signal, and if you wanted to step back, the direction and step got a signal. 

My question is, can I run directly from my parallel port to these inputs, or do I need to go through some other sort of board like the one attached below.  I was under the impression that the board in the attached picture would replace my three drives, not be before them in the circuit.

Any help would be appreciated.

Sounds like your drives may only be capable of using CW/CCW signals, if thats the case then possibly you could use MaxNC mode but I dont know enough about it so best do a search of the forum or look on the ftp site as I think it has pinouts.
Hood

 The PC parallel port is not capable (without additional circuitry) of providing a -5 Volt signal it is just +5 Volts or 0 Volts (within a certain tolerance).
 The board you have shown in the picture will replace your drivers and will be easy to hook up. Additionally it has the spindle relay and I think, would be ideal for a router.

Hope this helps,

Tweakie.

Tweakie,

So if I were to buy this board, I would connect to it with the PC's parallel port. Then from that to the motors.  All of the signal circuits will be internal basically...right?  Do I need a seperate power supply for the board, and one for the motors, or how does that normally work. 

Please keep in mind that my motors are Nema 42's and will be drawing a max of 65dc and 7.9amps per motor.

I dont know what the above board is but doesnt look it will be fit for these motors but looks can be deceptive, do you have the specs?
Have a look at the Chinese drives at Kelinginc.net  or the Geckos at geckodrive.com.

Hood

Hood,

I hadn't actually looked at the specs on it yet.  i just didn't know if I needed that and my drivers, or just that card by itself.  I am having trouble with my current drivers (they are so old they are not supported by the manufacturer, and I can't get any info on them.)  I will probably just buy one of the above drivers, but I will spec out the voltage and current before hand.

Ok if your old drives or no use then you will just need new ones, my preference is for separate drives for each axis and a breakout board to connect them all together and then the breakout connects to the parallel port. You dont really need a breakout board but it will be easier to connect things and it will probably make connection safer as well.
 The reason separate drives would be best is if one drive dies you dont have to replace the whole board, might be a bit more expensive in the first place but will likely work out a lot cheaper in the long run. Having said that I dont know of any combo drives like the one above that would be capable of powering your motors anyway, even Geckos and Leadshine (Chinese drives, Keling etc) will be at their max.
Hood

Please keep in mind that my motors are Nema 42's and will be drawing a max of 65dc and 7.9amps per motor.

The specs on ebay for this board say its 12-36Vdc and Max 3.5A / motor so I'm thinking it's not for your motors. Also there's an intriguing comment on the ad.

"*Important note: If you use  power supply 12-36V with lower current than 8 amps such as 12-36V 4 amps, the driver may be broken !"

Huh?

Cheers

Ian

As has already been said - This board is no good for 7.9 Amp motors.

Incidentally they sound a bit mighty for a router - they would drive Hood's Beaver. 

Tweakie.

they would drive Hood's Beaver. 

Tweakie.

Now stop getting personal