Messages

3991

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 18, 2018, 07:10:45 PM »

Hi Allan,
one situation, which as AC servo technology advances is becoming increasingly common, is serial encoders.

Delta's entry level encoder is 17 bit absolute and 20 bit absolute encoders are an extra. You may have noted that
Seimiens for instance have 23 bit muliturn absolute. Serial encoders will stonker the CSMIO.

The majority of modern AC servo drives have their own motion control built in as befits the emerging
'distributed motion control' paradigm sweeping through industrial CNC with EtherCat be the predominant
communication protocol. Ethercat is not common with Mach users....yet. Make no mistake as time goes on
it will. When that ocurrs our current motion controllers will lose the 'motion control' component and become an
EtherCat master.

Craig

3992

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 18, 2018, 06:29:06 PM »

Hi Allan,

the IP-A is capable of excellent results.

That the CSMIO/P-A is capable of great results is not in question, its just that its
not necessary to spend 700 pound to do it.

Mick is struggling to tune his servos, and he is still going up the garden path.....wouldn't happen with good
AC servos.

To Mick:
you should not throttle your servo speed back with RV2. Limiting the axis speed should be done in Machs
motor tuning page. The facility to do it in the  drive is for Velocity Never Exceeded imposed by physical plant,
eg lead screw whipping or reduction of over voltage spike on deceleration. Your servo and drive should be tuned for maximium
safe speed and acceleration.
Craig

3993

Mach4 General Discussion / Re: G-Code for Mach4 vs. Mach3

« on: July 18, 2018, 08:04:37 AM »

Hi Dave,
Steve is correct. This is a snippet of Gcode that is produced by software utility that produces Gcode for circuit boards.
This particular snippet is part of the PCB drill file. It works fine in Mach3 but not in Mach4.

Code: [Select]

N00160 G82 X33.4300 Y47.1500 Z-2.0000 F100   R1.0000  P0.500000
N00170 G82 X33.4300 Y52.2300
N00180 G82 X33.4300 Y59.8500
N00190 G82 X33.6000 Y12.0600
N00200 G82 X33.6000 Y17.1400
N00210 G82 X34.0650 Y34.4500
N00220 G82 X34.0650 Y42.0700
N00230 G82 X35.7400 Y66.1200
N00240 G82 X35.9700 Y52.2300
N00250 G82 X35.9700 Y59.8500
N00260 G82 X35.9900 Y6.6000 
N00270 G82 X35.9900 Y9.4000 
N00280 G82 X38.0000 Y14.5300
N00290 G82 X38.0000 Y17.0700
N00300 G82 X38.6700 Y63.3300
N00310 G82 X39.6400 Y60.9200
Note that the first line:

Code: [Select]

N00160 G82 X33.4300 Y47.1500 Z-2.0000 F100   R1.0000  P0.500000is complete with all the parameters of the canned cycle, whereas the second line:

Code: [Select]

N00170 G82 X33.4300 Y52.2300 is incomplete. The 'G82' code indicates to Mach to start a modal drill cycle but is then given an incomplete
list of arguments. Mach4 doesn't like it. If the incomplete 'G82''s are edited out...the resulting code is Mach4 compliant:

Code: [Select]

]N00160 G82 X33.4300 Y47.1500 Z-2.0000 F100   R1.0000  P0.500000
N00170 X33.4300 Y52.2300
N00180 X33.4300 Y59.8500
N00190 X33.6000 Y12.0600
N00200 X33.6000 Y17.1400
N00210 X34.0650 Y34.4500
N00220 X34.0650 Y42.0700
N00230 X35.7400 Y66.1200
N00240 X35.9700 Y52.2300
N00250 X35.9700 Y59.8500
N00260 X35.9900 Y6.6000 
N00270 X35.9900 Y9.4000 
N00280 X38.0000 Y14.5300
N00290 X38.0000 Y17.0700
N00300 X38.6700 Y63.3300
N00310 X39.6400 Y60.9200
Craig

3994

Mach4 General Discussion / Re: variable

« on: July 18, 2018, 07:48:18 AM »

Hi,
it is a fairly simple matter to read a register value.

LUA Syntax:
hReg, rc = mc.mcRegGetHandle(
      number mInst,
      string path)

This gets the handle of the register.

LUA Syntax:
value, rc = mcRegGetValue(
      number hReg)

This gets a numeric value. It may be that the value is stored as a string in which case you would use:

LUA Syntax:
buf, rc = mcRegGetValueString(
      number hReg)

You could then use all the standard arithmetic and mathematical functions within Lua and then write the result back to the same register
if you wish or another register of your choice. To make a new register use the Regfile plugin to create it. Then use mcRegGetHanndle() to get
the handle in the normal way and use mcRegSetValue() or mcReSetValueString() to write a value into the register.

Tell me a little more about what you want to do, maybe I can help with the code.

Craig

3995

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 18, 2018, 07:28:05 AM »

Hi Allan,

Does the DMM support analogue input, or would its use mean replacing the CSMIO as well?

Yes DMM servo drives support analogue input and so you could use the CSMIO but that would be crazy. Firstly many of the control features
would now no longer work because the CSMIO closes the loop, not the drive. Secondly DMM make the drive AND the servo and they are perfectly
matched to each other. You can get in there and tune if you wish but you'll have to do really well to better what DMM have done.

I don't see much difference in having the position loop within CSMIO as opposed to within the drive

That's like saying  'my Model T had a crank handle so my new sports car has to have a crank handle too'

Either way it needs some adjustment to suit the machine

You can manually tune the servo drive, although the pre-existing tuning procedures usually mean you don't have to.
Amongst the goodies is a software driven scope which allows you to visualize the adjustments you make in realtime, just so much more advanced
than the CSMIO.

Modern AC servos and drives, of which DMM is an entry level example, are so far advanced over previous methods with far greater flexibility and precision
of control that the CSMIO/A has been rendered obsolete. Do yourself a favour, don't believe me.....buy yourself an example, my preference is Allen Bradley
and prepare to be amazed.

Craig

3996

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 18, 2018, 03:45:52 AM »

Hi,

Before I can justify spending thousands on AC servos I need to give these a fair go.

Ac servos are not free but they don't cost thousands either.

DMM 200V Off-line Servo and Drive:
750W 200V servo                   $239
230VAC Drive                         $218
3m power & encoder cables     $71

Total                                      $528

This is for a modern AC servo which will eat the old stuff alive, 16 bit encoder, direct offline power supply, a multitude of control modes including step/direction,
vastly flexible electronic gearing, acceleration and velocity limits, programmable following error, zero error, multiple error reporting modes, indexed position and
velocity and the list goes on.

Note that the servo and drive form the loop, the controller is just a plain (cheap) open loop step/direction source....no closed loop controller required!
Ye-ha! Reduce confusion and tuning problems to a mere nothing! An AC servo and drive is as easy to hook up as a stepper driver, Mach can't tell the
difference between the two.

My experience is that I bought a modern AC servo second hand but have been so impressed I wont consider the old stuff any more.

I know its too early but the runaway first occurred when the Tach was not connected. Does this illuminate the possibility of being wired backwards

No.  If it runs with the tach disconnected it just means the amp operates without feedback. Look at the last diagram that I posted.....with the tach disconnected
then the feedback voltage Vfb is zero. Therfore error, e = Vin and the output current would be Iout= Vin.G, given that G is high even a modest input voltage will cause
significant output current and the motor will speed away. That's not faulty, that's just how it works.

If the tacho is connected and there is NO input, ie Vin=0 and the motor speeds away it means that the feedback voltage is generating its own input. This
is called positive feedback and is undesirable. If you reverse EITHER the tacho OR the servo then it becomes negative feedback which is what we want.

As I mentioned before could it be possible that the three-phase going into the drive needs the phases swapping to turn the motor the other way?

No, the three phases are rectified to produce DC. Phase reversal has no effect on the DC output.
Three phase induction motors will reverse the direction of rotation if one of the phases is swapped. If the direction of rotation is important, and  it usually is
then attention to phase rotation is required. Your servos should be unaffected by phase reversal.

Totally agree with you about using a 10v pot its a great idea. Should I disconnect the encoder wires from the CSMIO whilst doing that or just turn it off?

For testing purposes 9 or 10V and a pot would be good. Whether the encoder is hooked to the CSMIO is immaterial, the CSMIO might as well be off, we don't need it,
with perhaps the exception of an enable signal, to drive the servo.

Craig

3997

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 17, 2018, 08:59:01 PM »

Hi Mick,
Allan is 100%, the CSMIO and Mach is just distracting you from getting your servo to work.

If you can't get that working properly the ALL BETS ARE OFF. You could take the CSMIO and throw it
over your shoulder for all the difference it will make.

Use a signal generator as Allan has suggested or a 9V battery and a pot.

The runaway problem sounds like the tacho is reversed polarity relative to the servo direction, change one or the
other.

With reference to the last pic I posted, the feedback gain is RV1. The instructions say that you want to have the feedback
voltage Vfb nearly equal to the command input Vin. That assures the the error, e, is small. For a small error to produce
a large current/voltage output requires a high gain G.  If you cannot get a high enough output current/voltage despite
having a maximum command input voltage THEN you'll have to back the feeback off, its your only choice.

When the manual says the feedback voltage, Vfb, should be the same as the input voltage, Vin, I think close is better than
exactly the same. If they were exactly the same then the error,e, would be zero and you would not get any output
current/voltage at all! If the input voltage is 10V, make the feedback voltage say 9V. Now try adjusting RV2 to increase
the speed.

If you are thinking about sending one or more drives for repair I'd recommend considering replacing the drive and servo
with a matching modern AC servo/drive. You could bury the original servo and drive in the garden next to the dinosaur grave.

Craig

3998

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 17, 2018, 02:35:53 PM »

Hi Allan,
yes exactly, if indeed the drive has a velocity mode module fitted the I would have expected the amplifier to saturate almost immediately
the moment Mike opened the tacho feedback loop. From his description he had good control over speed of the servo. This leads me to believe
that the drive is faulty OR, and more likely, wildly mistuned in such a manner that it bears little resemblance to the manufacturers intention.

Craig

3999

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 17, 2018, 02:09:36 PM »

Hi Allan,
the symbols I've used relate to the pics they are used in, they have no relation to the terminology used by CSMIO.

My intention was to show, in the simplest of terms, the similarities of the two. A proper mathematical description of each
would hopelessly obscure what is was trying to do.

Craig

4000

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: July 17, 2018, 10:45:19 AM »

Hi,
I would still at least in the first instance follow the procedure in the manual. If the tacho proves good, and as Allan suggests I too think it likely that it is
good, then adjust the taco gain, that is Kt in my pic, so that Vf is nearly equal Vin. That assures a small error, e in my pic, which is the ideal.

I rather suspect that there is a fault with the amplifier part, G in my pic, it should have a very high gain which the feedback loop tames.  OPs experiment
of disconnecting the tacho results in sufficient gain where if it were operating normally the forward gain would be excessive.

Craig