Messages

2901

General Mach Discussion / Re: Software stops mid opperation.

« on: March 15, 2019, 11:23:58 AM »

Hi,

For the example above the parallel port
could  produce the required pulse streams  with a 100kHz kernel speed, but it couldn't go any faster and as you have pointed
out parallel port kernel speeds of 100 kHz are the exception not the rule.

Sorry, my contention that a 100kHz kernel speed parallel port could run our hypothetical machine is wrong.
The parallel port could produce the 100kBit/sec pulse streams to each axis but NOT fast enough for the spindle
as it requires a 200kBit/sec pulse rate.

Craig

2902

General Mach Discussion / Re: Software stops mid opperation.

« on: March 15, 2019, 11:12:35 AM »

Hi,
you misunderstand what is transmitted to an external controller. Your contention would be correct if an
external controller were simply a serial to parallel converter, but it is not.

Machs trajectory planner produces time slices of numeric data describing P(osition)V(elocity) over T(ime).
The controller then decodes the numeric data and using timers produce pulse streams in parallel.

The ESS uses 1024 time slices per second, near as dammit 1ms per slice. The packet of data will contain 4 bytes per
axis, for all six coordinated axes and another six Out-of-Bamd axes, for a total of 48 bytes per packet.
1024 packets per second for a total of 48kByte/sec. Note this includes the motion data only, various other IO
may increase it, but not that much. A ballpark figure is 60kByte/sec.

That (numeric) data is expanded into to pulse streams, lets say for arguments sake you have a three axis machine
with one OB axis, the spindle operating in Step/Dir mode, each with a motor tuning of 10,000 step/unit and the current
coordinated move requires all three axes to move ten units per second.
Each of the moving axes will require 100,000 pulses per second or 100 kBit/sec. If the spindle is required to rotate at 1200 rpm
(20 rev/sec) it will require 200,000 pulse or 200kBit/sec.
The combination of the three axes and the spindle will produce 500 kBit/sec of pulses in four simultaneous pulse streams.

The point here is that the pulse output rate is derived and determined by a much smaller, slower numeric data stream.
An external motion controller might receive its numeric data in serial packets but it produces independent parallel
output pulse streams which can be many orders of magnitude higher than the numeric data rate.

Note that Machs parallel port operates in an analogous fashion. PVT data is passed to the Ring0 pulse engine from
Machs trajectory planner, and ordinary Windows application. The pulse engine then generates the pulse streams.
Each independent output has a maximum output rate equal to the kernel speed. For the example above the parallel port
could  produce the required pulse streams  with a 100kHz kernel speed, but it couldn't go any faster and as you have pointed
out parallel port kernel speeds of 100 kHz are the exception not the rule.

Craig

2903

General Mach Discussion / Re: Software stops mid opperation.

« on: March 15, 2019, 02:18:13 AM »

Hi,
I run my step direction AC spindle motor at 458kHz with my ESS, rather faster than any parallel port. Still way under the 4Mhz
of which the ESS is capable.

Just in what way do you believe a general purpose CPU will outperform a FPGA or microcontroller replete with hardware
timers etc?

Craig

2904

Mach4 General Discussion / Re: mach4 m6 tool select issue

« on: March 14, 2019, 06:53:19 PM »

Hi,
there are two interpretations you can use with the 'T' word.

The first and most common to you and I (and any one else coming from a Mach background) is that the T word
is the tool number that will end up in the spindle when the toolchange is complete.

So:
m6 t5..........will result in tool 5 being fitted into the spindle.

There is another interpretation that is common in production machines. In that situation its common for the T word
to be the tool number of the NEXT toolchange. This would cause the tool carousel to be pre-positioned and therefore
speed up the toolchange.

Have a look  at Configure/Control/Tools

Craig

2905

General Mach Discussion / Re: Software stops mid opperation.

« on: March 14, 2019, 07:26:57 AM »

Hi,

Probably MACH4 is indicated if people want to use more powerful external motion controllers.

Funnily enough that is not quite correct either. The ESS for instance can be used with either Mach3 OR Mach4 with
the right plugin. The hardware is indentical, or you can swap between Mach3 and Mach4 without hardware change
at all. The same it true with the UC300 and 57CNC.

The true advantage of Mach4 is that is has a modular arrangement, a consistent API and a superior scripting
language. That makes Mach4 very flexible and can be adapted to wildly different machines.

The reason that Mach4 all but requires an external motion controller is because the developers at NFS realize that
a dedicated FGPA/microcontroller/DSP will always be able to outperform a PC's CPU in realtime operations. They have
therefore developed Mach4 to take advantage of external controllers and free Mach4 from the limitations of the
parallel port.

Craig

2906

General Mach Discussion / Re: Mach 3

« on: March 14, 2019, 04:06:15 AM »

Hi,
we can't possibly answer your question without some details. There is no limitation in Mach that prevents you
from going as fast as you tune your motors, or as fast as your motors will physically go or the kernel speed it exceeded.

What is the steps per unit value in your motor tuning?
What is the max velocity in your motor tuning?
What microstepping regime have you in place?

Craig

2907

General Mach Discussion / Re: Turning on the relay causes a 'limit switch triggered' error

« on: March 14, 2019, 02:18:46 AM »

Hi,
I was thinking that maybe you had a VFD and a asynchronous motor. For such motors line reactors
are appropriate.

For a DC spindle I would suggest a line filter like this in the AC input circuit:

https://nz.element14.com/corcom-te-connectivity/5vb1/power-line-filter-emi-rfi-5a-700ua/dp/2505259

In fact even between the DC controller and the motor would go a long way to suppress brush arcing.

Craig

2908

General Mach Discussion / Re: Turning on the relay causes a 'limit switch triggered' error

« on: March 13, 2019, 11:07:07 PM »

Hi,
there are two ways to approach EMI (electromagnetic interference).

Things like shielding cables, RC filters  on signal lines are all variations on the theme of 'decreasing the sensitivity
of signal circuits to EMI'. This is not the best, or perhaps the first approach.

The other way is to apply line reactors and/or filters to the VFD/spindle so that no EMI is generated. Then all signal
circuits operate is a low noise environment.

What sort of spindle are you using?

Craig

2909

General Mach Discussion / Re: Software stops mid opperation.

« on: March 13, 2019, 11:00:06 PM »

Hi,

I am still waiting for the external motion controllers to mature.

The good ones are already and have been for some time. That's not to say they wont improve and grow but they are
ready for serious work right now.

USB and Ethernet are NOT really suitable for the FACTORY environment.

You are correct with USB but you are 100% wrong about Ethernet....what do you suppose Ethercat and Profibus
are based on....you guessed it Ethernet. Ethercat and Profibus are the stand out performers in industrial control.

TCP/IP is known to be unreliable that is why the INTERNET must have multiple alternative paths and IP always has "time-to-live".

With multiple paths as are available with the Internet you have to allow for disordered packets, there is a setting you can make
however that requires all packets follow the same path and therefore NOT be disordered.  That multiple paths exist IS NOT
a REQUIREMENT of the Internet but rather a consequence of its dispersed structure. CNC is different.
Firstly you do not not communicate to a machine over the Internet, in fact it is not recommended to communicate over a network
or router either. The packet tracking order of TCP/IP is redundant, with PC to controller on a single Ethernet link
you can't possibly disorder the packets. Not that it matters, TCP/IP can reorder if necessary.

UC100 only has 1 second buffer.
ESS  has how many seconds of buffers?

The max ESS buffer is 500ms. You are mistaken however if you believe that a longer buffer is a good thing. If the buffer
is longer then if you issue a <feedhold> for instance the longer it takes for it to flush through the buffer. It is preferable
to have a short a buffer as possible. That increases the likelihood that the buffer will empty with bad consequences for your
job. The more powerful your PC and more memory and with the absolute minimum of extra software installed and/or running
allow you to shave the buffer ever lower.

My little dual core Atom Mini-Itx board is very low power so I leave its buffer set at 180ms as the plugin ships from Warp9
and I have never run out of data yet.

As I have proven, and as smurph has also proven with his Mud-board you do not need a hugely powerful PC.

My laptop is a few years old now but is I7 16G at 2.2GHz. It runs my machine indentically as my dual core Atom
at 1.8Ghz with 2.5G RAM (address space limited) and shared with video! The only thing my laptop does better is when I load
a big (10M plus) file and it has to decode and draw the initial tool path. My laptop does it in 5-10 seconds whereas the Atom can
take a minute. The bottom line is don't waste your money on a powerful PC, Mach doesn't need it.

The ESS is by no means the fastest controller nor is it the slowest, its pulse rate is up to 4Mhz, compare that to Mach's
parallel port at 25kHz default.

Rubbing sticks together is still a reliable way to start a fire, but there are better ways.

Craig

2910

General Mach Discussion / Re: Mach3 / Huanyang - Goto Variable Position

« on: March 13, 2019, 06:25:42 PM »

Hi,

Does the VFD produce noise even when the spindle is not running ?

No, I should think not anyway. The VFD starts to draw significant current only when the motor runs, and then it draws
current from the supply in short high current bursts rather than smoothly and that causes EMI. A line reactor 'smooths'
out the current and incidentally much improves the power factor.

When the motor is not running and the VFD is sitting idle there will still be a small amount of current draw as the auxillary
flyback inverter draws a few mA's to supply the VFD with a DC power supply. I would not expect EMI from that source
to cause your problem. If it does you are going to have a real battle when the motor runs and REAL current gets drawn!

On large industrial VFDs the AC supply to be used to convert to DC for the VFDs control circuits is separate to the main
AC input. That would allow much tighter filtering of the AC to DC supply without having to use hugely outsized and
expensive components should they have to withstand full input current.

Craig