out the LPT port- what is it?

[RogerTango]

I am still new at this, so bear with me.

I ordered the servo controller for my upcoming mill that I am building- It uses the parallel port (LPT) of the computer to receive information.

Say, I wanted to write my own software to control XYZ of the mill I built. What commands, in what formatting is sent out the LTP port?

I have never worked with a server controller before, so all this is new to me.

Thanks-
Andrew

[keebler303]

Your question is like: "How big is a tree?"

I don't know, what kind of tree is it?
Where did you buy it from?
Links?

Can't help yet.
Matt

[Andre' B]

If you really want to write some motion control software to use with a full servo motor system you should look into EMC, study the souce code and see how they have done things. All available for the cost of the download.
http://www.linuxcnc.org/

If all you want to do is simple step and direction output then you could look into TurboCNC the souce code only costs something like $60 and the jump you get over reinventing it all is more then worth that.
http://www.dakeng.com/turbo.html

As far as the controller you ordered, any quality hardware like that should come with some sample code one how to communicate with it.

[RogerTango]

Your replies were informative. However, let me reword the question for what I am looking for-

Lets say I am running Mach3 which communicates with a controller board by parallel cable and sends commands to it to tell it what to do with the three axis motors-

What would these commands be and where could I find a whitepaper or discussion on this data?


Thanks,
Andrew

[keebler303]

Mach3 controls a motor with step and direction signals. Each axis will have a step pin and a direction pin. Each time the step pin is pulsed (lo-hi-lo) the drive moves the motor one step (or microstep) if its a stepper motor, or one encoder count if it is a servo motor. The direction pin simply controls whether the motor is going forward or reverse. For example: if you wanted a normal stepper motor to turn 1 revolution, and you had a full step drive, mach would need to send 200 pulses through the LPT port as a normal stepper is 200 full steps per revolution.

There is no white paper needed for the process, its quite simple. The white papers come in when you have to translate a distance into a step sequence with acceleration and deceleration ramps, etc.

If your drives take step/dir signals, it is almost a no brainer to hook it up to mach. Again if you tell us what drives you are using, the replies could be more helpful.

Matt

[RogerTango]

Matt,
Many thanks my friend, that has been VERY helpful! I understand much better.

Here is the controller I just bought:

http://www.easy-cnc.com/web/download...3Axis(NEW).pdf

Thanks,
Andrew

[tokithecolector]

http://electronics-diy.com/stepper_motors.php

this site uses 5 pins 4coil +ground. The example program is at the bottom but i couldn't find the source. I think he's asking how to code in say c++ or something to do the same thing or if there is any library of lpt/com port controls

http://www.vclcomponents.com/C_C__/M..._car-info.html <-I found this just now it gives the source under more info maybe you could adapt it

Is it an xyz table, gantry, or a drill on the end of an arm(that would be cool)

[RogerTango]

Actually, I program in VB or VB.NET, but your tracking-

The page on the stepper motors was very informative also.

I am still trying to get down to the nitty gritty-

On page 2 of the PDF I posted a link to, it shows X, Y and Z DIR and STEP.

I am kind of needing to know more... Ill also try google later this evening.

Thanks-
Andrew

[MachMan]

I think you need to google "interfacing the parallel port".
PIN 2-9 are data out pins which give a binary representation of a
number between 0-255. If you output 0,(00000000) they will all be off and
if you output 255(11111111) the will all be on. Output '3' (00000011), pin 2&3
will be high so you get 1 step of X in DirX.
By changing this number you can do all kinds of things depending on
what those pins are connected to.
I've done alot of this in GW-Basic.
Good luck.
MM

[RogerTango]

MM, thanks for the help! Yes, I can program the LTP port, I built a little par. interface for the Commodore-64 a long time ago. All it did was cut on LEDs but I remember what I did.

I also found THIS page which appears extremely helpful in understanding WHAT I am supposed to send... PULSES! Not only what, but how-

http://www.fpga4fun.com/CNC2.html

It looked so good, I archived it here:
http://rogertango.com/pdf/fpga4fun_c...er control.pdf


I hope someone else finds it helpful also-
Andrew

(If interested, you can browse the index of: http://rogertango.com/pdf/ )

[MachMan]

Excellent link.
Exactly what you want to do.
Keep pulsing(toggle between) (0)00000000 & (1)00000001 for X+ or
(2)00000010 & (3)00000011 for X- (keeping pin 2(DirX) high)
I've had to use FOR-NEXT loops in between to slow the computer down.
You could always buy TurboCNC(excellent software for the price) and not re-invent anything but you did say something about 'nitty gritty'.
MM

[RogerTango]

Yup, Nitty Gritty is my middle two names.

BTW, I just uploaded a _BUNCH_ of new PDFs in that directory you may want to take another peek...

My learning curve is seriously coming up real quick with you guy's help and a little more understanding for a solid foundation!

I have some ideas.... For one, a PCB specific plotter program for resist pens, Id like to write it all in VB... Import the image, do a few guides, save it in the program's own format for use later, and control the whole machine in one program. Well, its a concept anyway. It wont be elegant, but it should work.

Cheers,
Andrew