Messages

4191

Mach4 General Discussion / Re: "Jog inc" is under ouput signals so how to trigger inc Jog step in mach 4??

« on: June 28, 2018, 08:54:20 PM »

Hi,
yes that would work although its not quite as straight forward as you might think. I'm pretty sure Daz
did a video about using an input signal like that.

I was going to ask ....why are you using the PoKeys? I know it will certainly work but given that you have an ESS as
your motion controller I wondered why you wanted to use the PoKeys as well.
The ESS has three ports so can be set up with about 31 inputs and 23 outputs, assuming you want max inputs that is.
Is there not enough IO with all of that?


4 axes         8 outputs
1 enable      1 output
spindle         2 outputs
coolant        1 output
TOTAL        12 outputs

homes          4 inputs
limits            8 inputs
probe           1 input
TOTAL         13 inputs

As far as I can see you are likely to have about 15 inputs and 10 outputs to spare.

Craig

4192

General Mach Discussion / Re: Mach III motor tuning with servos and G320X

« on: June 28, 2018, 08:43:10 PM »

Hi,
no, that suggests to me that it is indeed the servo drive that is signaling Mach to shut down.
It means that the drive is detecting one of the errors I mentioned.

When tuning you want to have all the fault warnings turned way up so the drive doesn't fault while you are tuning.
Once you have it dialled in you set the limits.

I will read the manual, but if memory serves there are two settings you can make.
One is the following error, you want it as wide as possible or even 'off' if you can. The other is overcurrent.
You want to set it to the maximum the drive can handle. Remember that current is proportional to torque
which in turn is proportional to acceleration. You want maximum acceleration when tuning, you may want to turn it down
later but you want it maxed when tuning.

Craig

4193

Mach4 General Discussion / Re: "Jog inc" is under ouput signals so how to trigger inc Jog step in mach 4??

« on: June 28, 2018, 06:40:46 PM »

Hi,
output is to be used if you want to turn a light  or LED on or off to reflect the Jog Inc state.

To change its state using a remote button use a general purpose input say ISIG_INPUT10 and then
in Mach code it so ISIG_INPUT10 changes the JogInc state.

Craig

4194

General Mach Discussion / Re: Mach III motor tuning with servos and G320X

« on: June 28, 2018, 06:08:01 PM »

Hi,

I don't have a direct fault line from there as it is simple as A+ B+ 5V+ and a negative that are fed from the encoder

That is from the encoder to the G320, you are interested in the lines between the G320 and your BoB/Mach.
I don't have the G320 manual in front of me but usually there is step, direction and enable lines
FROM your BoB/Mach to the G320 and one line FROM the G320 back TO your BoB/Mach to signal
a servo fault.

You may not have a servo fault signal setup but if thats the case then it cant be a servo fault thats making
Mach Estop, more likely noise on a limit switch say.

There are three common conditions that the G320 would recognise as a fault and signal it so:
1) Overcurrent, if you attempt to accelerate quickly, more than the G320 can handle or you progammed,
2) Overvoltage, usually happens if you try to de-accelerate to fast, the servo acts as a generator and will push
    voltage back into the drive, at a high enough level the drive will fault or worse blow,
3) Following error, if the servo lags behind its commanded position beyond a limit that you set it will determine
     that the accuracy of the machining job is at risk and fault.

Your Fluke scope should be isolated and so you could put a current shunt in the servo circuit to measure current.

Craig

4195

Mach4 General Discussion / Re: WHATS THIS ERROR..??? Clearing a spurious limit hit latch event,

« on: June 28, 2018, 05:29:39 PM »

Hi,

tried an it made worse an crashed everytime if by filtering you mean through ess on inputs

This is wrong somehow, there is no way increasing a filter time constant on an input should do that.

Have you electrically bonded all the metal parts together?. It sounds to me like you may have a power
supply issue or alternately some leakage current into the frame of the machine.

Try unpluging the spindle speed control from the AC line. If the motor has poor isolation it will
have leakage current into the frame of the machine and will very very easily overwhelm computer level
signals.

Craig

4196

Modbus / Re: Mach 3 Modbus TCP with Siemens Logo!8

« on: June 28, 2018, 05:01:32 PM »

Hi,
that pic is of the PLC program....you haven't got that far yet.

You need to program Mach to talk over TC/IP Modbus BEFORE you start worrying about programming the PLC.

Craig

4197

General Mach Discussion / Re: Mach III motor tuning with servos and G320X

« on: June 28, 2018, 04:57:24 PM »

Hi,
if you disabled the Estop how is it that Mach faulted?

You need to disconnect the servo fault line, not the Estop. Do this first and establish whether its a servo
fault or some other reason for the Estop.

You need to measure the current in the servo...you don't know at this point whether the
drive is maxed out or whether its just poorly tuned. Note a multimeter wont cut it, you need a good measurement
of peak current before you can start making decisions.

Craig

4198

General Mach Discussion / Re: Mach III motor tuning with servos and G320X

« on: June 28, 2018, 03:19:51 PM »

Hi,
you say that the machine Estops at random? What is it that makes you think that the servos are doing that?. I don't mean to say they aren't because
its common to have a servo fault trigger an Estop but you could have noise affecting one of your Estop signals and describe why its random.

Why don't you disconnect the G320 fault signal from Mach and try it again. If the servo is the real cause of your random faults then the Estops should
disappear. If they don't it points to a problem OTHER than your servo.

Do you have a current shunt or clip-on current probe for your scope? If you do insert the shunt into the servo circuit and measure the peak current. If its
near the maximum of the G320 then the driver is maxing out and probably faulting 'over current' before the servo is any where close to rated output.

If the measured peak current is less than the G320 max then the 'following error window' is too narrow, so the drive faults out 'following error' before it has
developed its maximum current. In the first instance open the 'following error' window as wide as you can and then start tuning. It sounds to me like your
Proportional gain is way too low. Easiest to set Prortional first and as high as you can with zero Inegral or Differential. Once you've established the
upper limit of P (as measured by peak current) back off a little and add some I, about 10%, then D for stability. Overall the best solutions tend to be high P
gains with enough  I for steady state following error performance and enough D for adequate phase margin.

Craig.

4199

General Mach Discussion / Re: Pulse per turn

« on: June 28, 2018, 02:53:19 PM »

Hi,
a 2500PPR encoder has 2500 lines, this is now the entry level standard for an incremental encoder. An incremental encoder has an A and B phase in phase quadrature, ie
90 degrees apart. That means you get four encoder counts per line, so 10,000 counts per revolution.

If you put 10,000 in your axis motor tuning 'steps per unit' ( this assumes no electronic gearing within the servo) and then issue:
G0 X1    Mach will try to move one unit by producing 10000 pulses.

If in fact your axis moved 2.345 mm rather than the 1mm you requested you can use that to recalculate the 'steps per unit' value:

steps per (true)= (unit distance)/ (actual distance moved)  X (estimated steps per)
                      = 1 / 2.345 X 10000
                      =4246.4

As a sanity check....if Mach issued 10000 pulses and the axis moved 2.345mm then if I wanted it to move 1mm only
then Mach will need to issue fewer pulses, in which case 4246.4 ( being less than 10000) sounds about right.

Craig

4200

General Mach Discussion / Re: Mach 3 changing stepper motors configuration

« on: June 28, 2018, 02:34:39 PM »

Hi,
just enter the correct 'steps per unit' value in the Z axis tuning page. You will have to experiment to find the correct max velocity and accel.
Good place to start is the speed of the axis if the stepper is doing 500 rpm. Thus if the axis has a 5mm pitch ballscrew then the max velocity
would be in the region 500 X 5 =2500 mm/min. Common to start with accel of 10% of the max velocity, so accel=250.

Craig