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Author Topic: BB card vs motion control card  (Read 1849 times)

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BB card vs motion control card
« on: October 16, 2016, 02:59:58 AM »
Hello everyone

I converted a number of machines, lathe, milling machine and laser cutting machine,

They all used the parallel printer card.

I wonder what the benefits of the motion controller unit  compared  to the parallel printer card ?

Thanks in advance

y_shalom

Offline Davek0974

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Re: BB card vs motion control card
« Reply #1 on: October 16, 2016, 03:54:34 AM »
One is that you get away from needing a parallel port - newer pc's need a card adding and still get stuck with 32bit OS.

USB is a step ahead but can sometimes play up a little, I think the best option is ethernet.

I'm not sure but i think i also read that motion can be smoother with external controllers.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: BB card vs motion control card
« Reply #2 on: October 16, 2016, 06:14:32 AM »
Thank you for the answer .

Is the use of servo motors Requires  controller of this kind?

Perhaps the pulse rate speed ?

In the end one  can add a parallel card(s) to any computer .

It is a relatively very cheap Compared to motion controller .

Regards

y_shalom

Offline Tweakie.CNC

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Re: BB card vs motion control card
« Reply #3 on: October 16, 2016, 06:42:44 AM »
Quote
In the end one  can add a parallel card(s) to any computer .

There are many good reasons for using an external motion controller although my personal preference is using the parallel port with Windows XP but
please keep in mind that the parallel port can only be used with 32 bit operating systems running Windows 7 (or earlier) and laptops are not supported.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Davek0974

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Re: BB card vs motion control card
« Reply #4 on: October 16, 2016, 08:01:01 AM »
If i'm wrong someone will correct me but I'm fairly certain the the parallel port will not handle the encoder signal and pulse rates needed for servos very well. My encoders are 10,000 per rev and motors can do 3000 rpm so it needs a pretty fast connection.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Tweakie.CNC

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Re: BB card vs motion control card
« Reply #5 on: October 16, 2016, 08:26:59 AM »
If i'm wrong someone will correct me but I'm fairly certain the the parallel port will not handle the encoder signal and pulse rates needed for servos very well. My encoders are 10,000 per rev and motors can do 3000 rpm so it needs a pretty fast connection.


This may be entering into the twilight zone but note to self…
“Tweakie be prepared to be hammered”  ;D ;D

Mach3 is not a closed loop system so does not get to see the higher speed encoder signals that are required by the servo drives to verify that the step direction signals have been performed correctly.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Hood

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Re: BB card vs motion control card
« Reply #6 on: October 16, 2016, 09:39:41 AM »
Well the way a Step/Dir servo works is it takes Step/Dir signals and the drive outputs the voltage to the motor based on that. The Step/Dir is based on the encoder so if you have 10,000 pulses per rev on the encoder and you have 2:1 reduction and 5mm pitch screws then the steps per unit required in Mach would be...
10,000 x 2 /5 = 4,000
So even if your computer is good enough to get the kernel to 100KHz the max velocity you could achieve is 25mm/second or 1500mm/min.
In reality you will likely find 45KHz to be a more realistic kernel speed from the parallel port so your Max velocity would be 675mm/min.

Now there is a way to get round this, most servo drives have a form of electronic gearing where you can tell the drive that 1 pulse from Mach is equal to a certain number of pulses, so say you set it to 4 then that would allow you to achieve 4 x the 675mm/min, set it to 10 and you could get 10x the 675.
Downside of using electronic gearing is it can make the motion rough (cogging) at low speeds and that is where the fast pulsing of most external controllers comes in, it allows you to use Mach with no electronic gearing in the servo drive.

Hood
Re: BB card vs motion control card
« Reply #7 on: October 17, 2016, 02:17:41 PM »
Thanks for the information Hood

y_shalom