Fanuc 12 bit binary spindle control

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14 Oct 2017 08:42 #100343 by johnmc1
Good Day All

I seeking information on using Linuxcnc to control the Fanuc dc spindle fitted to a Matsuura milling machine,which I am about to refit with Linuxcnc.
The Fanuc DC spindle control is model A20B-0005-0372/14F.
The spindle control requires a 12 bit binary signal that is then converted by a D/A converter to a analog 0 to 10v signal.
There is also a forward and reverse signal for direction.
Please advice on the following possible solutions ..
Try and tap a analog signal into the control and by pass the DAC module.
Convert the Linuxcnc analog signal to a 12 bit binary signal as per fanuc.
Replace the spindle drive.
Thanks in advance .
john

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14 Oct 2017 14:13 #100349 by PCW
What voltage are the bits? could you just use parallel port bits
(or whatever output bits you have) to drive it?

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15 Oct 2017 04:18 #100365 by johnmc1
Thanks for your reply

The bits are tied to ground to become active,also
I would be able to use free output bits, with free M codes for speed control

john

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19 Oct 2017 14:05 #100551 by andypugh
Might be a job for an arduino nano.

But, you should be able to do it with output bits and the "bitslice" HAL component.
linuxcnc.org/docs/2.7/html/man/man9/bitslice.9.html

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20 Oct 2017 21:47 #100598 by johnmc1
Thanks for your reply,
The bitslice hal component I do not understand how it would be implemented.
What I need is a method in Hal,to change the linuxcnc S command to a 12bit digital signal for Fanuc spindle control.
The arduino nano is method that has possibilties.
john

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21 Oct 2017 02:26 #100600 by andypugh
Is this 12-bit digital signal sent as 12 parallel bits or a serial stream?

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21 Oct 2017 04:51 #100605 by johnmc1
The 12-bit signal is sent as 12 parallel- bits .
I also believe that fanuc spindle drive holds the signal for about 8 seconds before it can update and that,
12, low bits equals maximum speed, while 1, low bit equals minimum speed.
john

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21 Oct 2017 11:24 - 21 Oct 2017 11:25 #100608 by andypugh
That last part (all zero for max) is a bit awkward.
Time for a custom component.

linuxcnc.org/docs/2.7/html/hal/comp.html
component fanucspindle "convert spindle speed to 12 parallel bits";

pin in float max-speed = 1000 "maximum spindle speed";
pin in float spindle-speed "spindle speed command";
pin out bit bits-##[12] "output bits";

function _;
author "andypugh";
license "GPL"; // indicates GPL v2 or later

;;

#include <rtapi_math.h>

FUNCTION(_){
	int speed;
	int i;
	if (spindle_speed < max_speed * 0.0004) {
		speed = 1;
	} else if (spindle_speed > max_speed * 0.9995) {
		speed = 0;
	} else {
		speed = fabs((spindle_speed / max_speed)) * 4095;
	}
	
	for (i = 0; i < 12; i++){
		bits(i) = speed & 0x001;
		speed = speed >> 1;
	}
	
}
Last edit: 21 Oct 2017 11:25 by andypugh.

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22 Oct 2017 12:08 #100627 by johnmc1
Good Day Andy.

Many thanks for your Custom component.
It will take a while for me to digest the component .
To muddy the waters even further, the spindle gear box ratios as per Matsuura manual.
H speed 0.903 to 1
L speed 0.198 to 1
Can this be allowed for in the custom component,
or is the gearbox ratios attended to in Hal
john

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22 Oct 2017 12:45 #100630 by andypugh
Is it an electronically-controlled gearbox?

I have a HAL component that I use on my 2-speed + VFD lathe which controls the electronic clutches for me. And I have another system on my mill which works out what gear is engaged on the manually-operated gearbox.

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