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Author Topic: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)  (Read 24947 times)

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Offline Hood

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Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #50 on: March 30, 2011, 06:11:27 PM »
Lets just stick with Z as all details are known about it, ie pitch of screw, direct coupled and the only thing is encoder counts or drives electronic gearing.

Ok so if it is 4000ppr then that would mean each 4000 pulses would move the Z 0.1inch so 40,000 pulses would be your steps per inch. You have 10,000 set however so  if you zero the Z axis and command a G0Z-1 move from the MDI line does it move 1 inch?

If it does then either the encoder is 250 line (1000ppr) or you have 4x electronic gearing in the drive or you have a scaling value of 0.25 set for the Z axis.
Hood

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Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #51 on: March 30, 2011, 06:16:08 PM »
In the Viper manual it does state this:
125Khz max step rate.

"The viper can handle up to 625Khz
encoder frequency (assuming good cableing )"

Even more confused!!

Two different things really as the pulses are from Mach via the parallel port and the encoder is direct to the Viper. Could be the opto used for the Step/Dir input is only capable of 125KHz and there is no opto on the encoder inputs. Could also be just a recommended max of Step/Dir and you may find you can get more, you would really have to ask the Viper guy to find out for sure.
Hood
Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #52 on: March 30, 2011, 06:28:25 PM »
AH HA! Look what i found. Remember how i said i had jumper in the step multiplier?
Well apparently programmable step multiplier must not mean 1X. Below it states "any size"!
It must be a default setting in the drive that i have to configure i bet.. I cant find the command to do it though.
You have to use hyper terminal and RS232 to program the drive.


-  1 ,2 ,4 ,8   s te p   mu ltip lie r  (o r  a n y  s ize
Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #53 on: March 30, 2011, 06:29:12 PM »
*i had no jumper (sorry typo)
Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #54 on: March 30, 2011, 06:32:01 PM »
Page 30 for commands and 32 for step multiplier.
http://www.larkencnc.com/dloads/viper-manual.pdf

Would the "enter step size" command be what i need to look @?

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Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #55 on: March 30, 2011, 06:44:54 PM »
It does look like it but I would have to read the manual properly to know for sure, even then it may be ambiguous as manuals often are. Give Larry a quick email and see if he can advise..
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Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #56 on: March 30, 2011, 06:55:21 PM »
Just had a quick skim through the whole manual and really there is not much info on it but it does look like it is that setting. If you connect to hyperterminal and look you will see what the J (ju) is set to, my guess is it 0004.
Another thing you could do is put the jumper on the 4x pins and see if it is exactly the same, if it is then you know its set to 4x in the drive.
Hood
Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #57 on: March 30, 2011, 07:48:24 PM »
Larry saved the day again! He confirmed what we thought. It was set to 4x.

With no jumper on , you set the j command in the drive.
With jumpers on the j setting is set by the jumper.

EG : with no jumpers on, j5 sets 5 encoder counts/step.

I don't recommend a 1X setting as the drive error is usually a few counts. 4X  gives the same resolution as the Line count.
since 1000 line, and with quadrature they are 4000 counts per revolution.
Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #58 on: March 30, 2011, 09:09:34 PM »
I think i will keep it @ 4x. It seems to give me a good amount of speed and the resolution as you stated is very very small.

I also remembered the "top speed" in the servo spec sheet is listed @ 3200rpm @ at a voltage constant of 90VDC. I have a 105VDC power supply.

That is an additional 16% voltage, which i have been told by a few industry professionals is a common practice to do.

If voltage and speed are a perfect linear relationship then that would mean i would have an extra 512RPM, giving me 3712rpm max.

What would my new servo max speed be if limited by my driver? I tried to do the math but it gives me a funky number in return.

Larry says-
"I don't recommend a 1X setting as the drive error is usually a few counts. 4X  gives the same resolution as the Line count.
since 1000 line, and with quadrature they are 4000 counts per revolution,"

So even with 4x setting on, i am still getting 4000 counts per revolution or only 1000?

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Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)
« Reply #59 on: March 31, 2011, 03:25:59 AM »

I also remembered the "top speed" in the servo spec sheet is listed @ 3200rpm @ at a voltage constant of 90VDC. I have a 105VDC power supply.

That is an additional 16% voltage, which i have been told by a few industry professionals is a common practice to do.

If voltage and speed are a perfect linear relationship then that would mean i would have an extra 512RPM, giving me 3712rpm max.

What would my new servo max speed be if limited by my driver? I tried to do the math but it gives me a funky number in return.

I dont know what servos you actually have but the 80's vintage DC servos that were common on milling machines usually had voltage ratings of 160v but more often than not the power supply was around the 100v and then with the losses in the drives the actual voltage the motors got was 90v or so. Your motors should have a max voltage and current rating and I would not go over that.
One thing however is the problem you have at the moment is the drives limit on its step/dir input, so going faster would require you to reduce the resolution, this may or may not be a problem for you but something to think about.


Larry says-
"I don't recommend a 1X setting as the drive error is usually a few counts. 4X  gives the same resolution as the Line count.
since 1000 line, and with quadrature they are 4000 counts per revolution,"

So even with 4x setting on, i am still getting 4000 counts per revolution or only 1000?

You are only getting resolution based on the  1000, Mach will put out 1 step and the drive will treat that as 4.
 I personally am not a fan of electronic gearing and was why I was overjoyed when I got the Beta SS as it allowed me to get full potential from my drives. I have 2000 line encoders so thats 8000 per rev but as my drives can handle 2.5MHz input that is not a prblem, I am not even using a fifth of that.

Hood