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Author Topic: Problem with pp port ?  (Read 5131 times)

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Offline mick

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Problem with pp port ?
« on: September 22, 2008, 01:47:40 PM »
Hello all,
           The problem i have is getting mach to output 0-5volts on pin14 to control the anolog speed control which is 0-10v.
            In ports & pins /spindle :-step pin 14, dir 8, port 1,
            In motor tuning/spindle :-steps per 1000 , velocity 1500, pulse 3.
            Spindle pullys:-Max speed set 1220 ,ratio 1:1
             
             With the command m3s1220 the voltage on pin 14 changes from  .08volts to .25volts. however if pin14 is setup as dir pin
             on either z or x the voltage swings from .08v to 4.4v .
             
             tried deleteing the xml,s and re-installing mach, but still no joy .
             
             help please,
                               rgds mick.

Offline Chaoticone

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Re: Problem with pp port ?
« Reply #1 on: September 22, 2008, 10:41:33 PM »
Mick, post your xml. Also have a look at your settings in motortuning and compare the spindle motor to the axis.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

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vmax549

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Re: Problem with pp port ?
« Reply #2 on: September 22, 2008, 11:20:05 PM »
This may be obvious BUT the PP cannot do analog voltage output. You have to use a convertor board to change the step/direction or pwm to 0-10v dc to drive the speed controller .

(;-) TP
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Offline jimpinder

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Re: Problem with pp port ?
« Reply #3 on: September 23, 2008, 03:21:46 AM »
Mch controls spindle speed by two methods, one is step and direction - just like an axis.

The other is by Pulse Wave Modulation. In PWM, no direction information is given. The sole output is on the "Step" pin. This is in the form of a frequency output (which can be selected) of a 5 volt signal. This is then modulated (i.e. turned on and off) in proportion to the speed required. The result is a square wave signal which varies its ons and offs according to the speed. E.g. quarter speed - 25% on 75% off, half speed 50% on 50 % off. etc.

This resulting voltage can be read by a volt meter, but not very efficiently, and can be seen to vary as you increase the  speed of the spindle. To convert this into a voltage signal that can be read by an inverter, or control equipment, you need something like Digispeed, which converts the PWM signal into a varying voltage signal (0 - 10 volts) which controls your inverter.

Direction (on my machine) which has an Omron inverter is still controlled by M3 or M4 output. The outputs to these signals are on two seperate wires on the output set 1,14,16 or 17 (or actually I use pins 8,9 because I don't have fourth axis) with the PWM coming out on pin 17.
Not me driving the engine - I'm better looking.

Offline mick

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Re: Problem with pp port ?
« Reply #4 on: September 23, 2008, 11:08:34 AM »
thanks Brett,
                  here's the xml.
                                       

Offline mick

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Re: Problem with pp port ?
« Reply #5 on: September 23, 2008, 11:26:51 AM »
TP,
     yes i have a cnc4pc c14 5volts  to 10volts converter, but can't get more than 8.7volts out, and that is with the pulse set to 8.


Jim,
     Thanks  for explanation, today i monitored the pp with a scope while trying different settings in motor tuning.
      the only setting which makes the output voltage vary is the pulse width,but even values of 15 don't get 10 volts
      out of the converter.
                                     thank mick.










                         
Re: Problem with pp port ?
« Reply #6 on: September 23, 2008, 12:03:52 PM »
Hey Mick, like TP said earlier.....
The C14 is an analog voltage converter, analog in...analog out. It will not convert either Step and Direction or PWM signals from Mach3 to an analog voltage.
The C14 is used with some Gecko  ......I think.   Yes...the G-Rex puts out 0-5 analog, there you would need the C14.
RC

You would need the C6 board.
http://www.cnc4pc.com/Store/osc/product_info.php?products_id=58
« Last Edit: September 23, 2008, 12:32:45 PM by Overloaded »

Offline mick

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Re: Problem with pp port ?
« Reply #7 on: September 23, 2008, 12:35:48 PM »
RC,
     Thanks for putting me on the right track.
     i have  been trying to use the output from pin 14 on a c11g BOB to feed the input on the c14 because i could not get
     the on board anolog output to work.
 
                                                        many thanks mick.

                                             
Re: Problem with pp port ?
« Reply #8 on: September 23, 2008, 12:42:54 PM »
Mick, the C11's are a bit tricky to set up. The settings that actually work may not necessarily be the settings in the manual.
There is a good topic on this...I'll try to find it.
RC

http://www.machsupport.com/forum/index.php/topic,6707.0.html
« Last Edit: September 23, 2008, 12:45:43 PM by Overloaded »

Offline mick

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Re: Problem with pp port ?
« Reply #9 on: September 23, 2008, 02:07:19 PM »
Thanks RC,
               There's plenty to get my teeth into in that topic.
                                                                                 rgds mick.