Messages

71

Modbus / Re: mod i/o and Vfd control on same port?

« on: December 15, 2014, 06:28:39 AM »

Hi John,

Yes you can. The ModIO has an inbuilt RS232-RS485 converter in it. You can connect the ModIO to the PC via RS232 then use the RS485 bus on the ModIO to connect to the VFD.

You will need to write the brains to get Mach3 to control the spindle speed via Modbus.

I wrote an article on how to to use Modbus with Mach3. You can download it from the documents page(about 1/2 way down) on my store.

http://www.homanndesigns.com/store/index.php?main_page=page_2

There is also an engineering note "EN007M MC-01 ModIO™ as RS-232 to RS485 Converter" on the same page that details setting the modIO up to do the RS232 to RS485 conversion.
 

Cheers,

Peter

72

General Mach Discussion / Re: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller

« on: August 27, 2014, 05:35:39 PM »

Hi Marty,

I meant "Speed until"

Increase the speed via Mach3 until you get 10,000 rpm  measured spindle speed.

Cheers,

Peter

73

General Mach Discussion / Re: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller

« on: August 27, 2014, 02:53:52 AM »

Hi Marty,

Sorry, I missed that you were getting double the spindle speed out at 100% PWM.

What you need to do is set up as I suggested with the MAX pot set fully CW.

Set the pulley max speed to 100. Then increase the the speed unit  you get 10,000 rpm and not the set speed value.

If the value was say 35, then the max pulley speed that you need to set is 100/35 * 10,000 = 28,571 rpm

This should put you in the ballpark to fine turn from there.

I thought that Mach3 has a max pwm setting but I can't find it. If set to 35, it would allow you to set the max pulley to 10,000rpm and when you set the speed to 10,000 it would only output a 35% pwm signal.

One of the problems is that you are only using the motor in the bottom 1/2 of it's range. This will mean theat the non-linearity at low speeds will be about twice what it would normally be.

One of the solutions would be to replace the pulleys doubling the reduction to allow the motor to use more of it's range.

Cheers,

Peter

74

General Mach Discussion / Re: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller

« on: August 26, 2014, 09:59:37 AM »

Hi,

This is a copy of the post I put on the Mach3 group.

There are quite a few things at play here.
Firstly, you cannot test the linearity of the G540 output using the KBIC's  as
the supply for the G540 analog circuitry.

If you want to test the linearity properly you need to use a stable supply. A
9V battery is a good choice. Connect the battery to the 10V+ and the Agnd
terminals on the G540. Then
1. in Mach3 set the spindle speed to max (10,000rpm in your case)
2. Measure the analog output between Aout and Agnd on the G540.
3. Multiply the measured voltage by 100 and enter that as the max pulley speed
into the Mach3 pulley setting. So a measured voltage of 8.90 would mean that
the max pulley setting entered is 890rpm.
4. Now you can test the G540 linearity. Enter 100rpm and the voltage should be
1.00V. Enter 250rpm and the measure voltage should be 2.50V

You should find that the linearity is very good.

Now on to your setup. If you are powering the G540 Analog supply from the
KBIC-120 connecting it in place of the 5K pot (which is exactly what I do) The
voltage supply is about 15V.

WARNING!!!!  This 15V supply is LETHAL. Terminal P3 is at mains potential
110V,220V,etc. P1 is 15V less than that. P2 varies between the two. If you are
not qualified to work on mains voltage, use someone who is. (a qualified
electrician)

Jeff's document instructs you to use the voltage following input setup which
not the same as just replacing the manual speed potentiometer with the G540
analog output.

I have always controlled the KBIC controllers by connecting to the three
potentiometer terminals, P1,P2,P3
I have done this with all my DigiSpeed Products and the G540.

One of the problems you are encountering is that the 15V supply is a diode
shunt regulator, capable of only supplying a few milliamps. Further more, the
MAX trimpot is just a potentiometer that is in series with the 15V supply.
Also the G540's dynamic impedance (load) that is across this supply varies
with the PWM signal. So as you vary the Mach3 speed setting, the supply
voltage to the G540 analog setting varies because of the voltage divider set
up by the MAX pots resistance causing a non-linearity in the 15V voltage
supply to the G540.

If you want to use the voltage following input as Jeff suggests you need to
power the G540's analog circuity from a separate isolated 7V supply and not
the 15V supply for the potentiometer.


And another issue to deal with is the non-linearity of the spindle motor. At
very low speeds, the motor needs to overcome the friction and drag in the
motor and drive train, so the actual speed will be less than the commanded speed.

Then at the top end, the spindle speed of the DC motor saturates (flattens
out) after about 95% of top speed. So in essence, the DC motors response is
actually an S curve, not a straight line. So when you are setting the Max
pulley you need to use the estimated speed that it would have reached if it
did not flatten out.
What this means that you should have very linear response is the 15%-85% speed
range. Above 85% you usually just want to go flat-out so the non-linearity in
that part is not usually a problem.

So to set up your spindle,
1. Connect the G540 analog lines in place of the P1,P2 and P3 potentiometer
terminals of the KBIC-120
2. Wind the MAX pot fully clockwise to reduce any non-linearity from it.
3. Run the spindle for 15 minutes to warm up so as to reduce drag in the
drive-train.
4. Set the Max pulley speed to the max speed that the spindle would reach if
it did not flatten out.
5. Adjust the Max pulley speed so that you get a linear response in the main
working speed range of your spindle.

Hopefully this will get you close. If you are not happy with the result you
may need to replace it with a Closed loop spindle control system such as a VFD
or servo.

Cheers,

Peter

75

General Mach Discussion / Re: ANDing motor index pulse and a second switch to detect home position

« on: July 02, 2014, 11:04:21 AM »

Hi,

I don't know but I would think not as it is outside their specifications.

There are 5V proximity sensors though.

Cheers,

Peter

76

General Mach Discussion / Re: ANDing motor index pulse and a second switch to detect home position

« on: July 02, 2014, 05:51:54 AM »

Hi Drew,

Yes, they are NO. If you have NC switches, put them in parallel to achieve the same result.

Cheers,

Peter

77

General Mach Discussion / Re: ANDing motor index pulse and a second switch to detect home position

« on: July 02, 2014, 12:51:53 AM »

Hi Drew,

Yeah sure. Connect the two switches in series as shown here;
http://www.accentsensors.com/help2.aspx

Assumes that the new switch will also be a proximity switch.

Cheers,

Peter

78

General Mach Discussion / Re: idiots guide to servo motors and drives please

« on: June 22, 2014, 10:10:11 PM »

Hi,

This is an AC servo motor. Unless you have the driver matched for this motor, I'd leave it alone.

The driver you have identified is for a stepper motor and not suitable as a servo driver

Cheers,

Peter

79

General Mach Discussion / Re: Modbus Serial Plugin Issue

« on: June 16, 2014, 09:04:18 PM »

Hi,

Good to see it working.

In the PLC, multiply your value by 1000. Your value will then be from 0 to 2600. You should then be able to put it into a WORD (16bits). Then transfer this to Mach3.

Cheers,

Peter

80

General Mach Discussion / Re: Modbus Serial Plugin Issue

« on: June 16, 2014, 05:02:32 AM »

Hi,

Attach a screen dump of your serial modbus plugin setup screen and your legacy modbus setup screen and I'll have a look and see if I can spot anything.

Cheers,

Peter