Messages

451

General Mach Discussion / Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine

« on: December 07, 2011, 01:08:32 AM »

If I switch it in mach then i get no motion. If switch it in the motor driver then I get reversed motion.

Are you sure you don't have Step and Dir swapped?  I can't see what else could explain what you're reporting.  You might want to try either swapping the wires or the pin assignments in Mach3, and giving it a try.  It would explain what you're seeing.

Regards,
Ray L.

452

General Mach Discussion / Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine

« on: December 06, 2011, 11:57:24 PM »

What happens if you change the ActiveLow setting for the DIR signal in Ports&Pins?

Regards,
Ray L.

453

General Mach Discussion / Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine

« on: December 06, 2011, 10:00:07 PM »

I would first do away with the potential complexities of treating it as a spindle motor, and just set it up in Mach3 as a linear axis drive, and see if you can get that to work.

DIR timing should not be an issue unless you're reversing the direction.  It should still work fine in ONE direction ,as the DIR pin will never be changing state.

Regards,
Ray L.

454

General Mach Discussion / Re: Steppers are too slow

« on: December 06, 2011, 04:50:52 PM »

I'm not sure I understand the question. I don't think I said a chopper would "limit" the current to less than the max setting. That doesn't mean the stepper will always draw maximum current.

This and your earlier comment that load affects current is what I don't get. As I understand it, the chopper by it's very nature is monitoring the current through the motor. ONLY when the current through the motor reaches the set point will the chopper start to chop. (There will of course come the time with motor speed when the voltage simply can't drive the required current because of inductance and ultimately the motor will stall but that's not what we're talking about here). I can see no reason how external mechanical load can affect the current through the motor. Servos yes but steppers no. Maybe I'm wrong.

Ian

That's not how choppers typically work.  They normally run at a constant switching rate, with the pulse width varying based on commanded output.  Current limiting will prematurely turn off the output current, ONLY if the limit is exceeded.  At low pulsewidths, and/or low loads, you'll never reach the limit, because the current is not turned on long enough to saturate the coil, due to the coil inductance .  The whole idea is to vary RMS voltage, allowing the current to do what it will, provided it does not exceed the set limit.

Regards,
Ray L.

455

General Mach Discussion / Re: Steppers are too slow

« on: December 06, 2011, 04:17:36 PM »

For a DC ammeter (or multimeter in DC current mode), the idea is to use a shunt to measure the current. Basically, we have two paths for the current to flow through - one main bypass to move most of the current around the metering device, and a low current shunt to measure the current. This method is actually going to measure the voltage drop across a shunt resistance, and using the value of the shunt, calculate what the current should be. It's important to note that here we are actually measuring DC voltage. In addition to this, there are various ways the internal circuitry can be arranged - the shunt configuration differs from meter to meter so results in this situation will not be same with all meters, but in any case it should not be considered accurate.

Never seen a current meter work as you describe.  A shunt is nothing but a VERY small resistance, on the order of milli-ohms, typically provided by a simple strap of brass or copper, necked down at one point, and trimmed at the neck to provide the required accurate, small resistance.  ALL of the current flows through the shunt, and its resistance creates a small voltage, which is displayed on a moving-coil meter movement with, typically, 50mV full-scale sensitivity.  A DVM works in exactly the same way, except measures the voltage with an A/D converter, rather than an analog meter movement.

Regards,
Ray L.

456

General Mach Discussion / Re: G31 Probe problem

« on: December 06, 2011, 04:08:48 PM »

Just and update to what I said about FIFO and one-shot. I'm not sure but I think this has changed at some time. I THINK you can now send multiple CODE statements without an isMoving() after each one. I THINK you can now get away with a series of CODE statements with just one while isMoving() after the last one. i.e. I THINK Mach buffers the CODE requests in order. Is it reliable? - your guess is as good as mine - which version do I think it changed in? - I don't know. I still stick an isMoving() after each one - but that's just me.

Ian

Ian,

That is correct.  That change was made perhaps two years ago, back around v30-something.  It was done at the request of David Bagby, to make MachStdScreen work better.  AFAIK, it does work reliably.

Regards,
Ray L.

457

General Mach Discussion / Re: Parallel port PCI, or Parallel port PCI Express?

« on: December 06, 2011, 10:29:20 AM »

I would expect a regular PCI parallel port card to work better than PCIExpress.  PCIExpress is basically a high-speed serial interface, and will inherently introduce jitter into the signals.

Regards,
Ray L.

458

General Mach Discussion / Re: Scripter Compile Errors

« on: December 01, 2011, 10:05:16 PM »

HIYA RAY, To each his own, But from the sounds of the earlier comments you are not doing well at all. Still suffering fromteh Lost Mach Syndrome

I feel your pain but there is little i can say to make it better other than YEP it should get fixed.  But I am just  speaking to the Choir (;-)

(;-) TP

Terry,

Yup, but, like I said, as bad as it is now, it's still MUCH better than it was.  I am still inching towards switching to KFlop, but it's a big project, due to all the wiring changes, and all the KFlop code that needs to be written to duplicate the essential functionality I have in Mach3.  The last bit is getting my pendant moved over, and I just bought the bits I need to make the cable today, so I should have the pendant going soon.

Regards,
Ray L.

459

General Mach Discussion / Re: Scripter Compile Errors

« on: December 01, 2011, 08:26:52 PM »

Hiya Ray there is a reason that a lot of us stay at the 3.042.020 version or very close to it.

(;-) TP

Terry,

I would do the same were there not many crippling bugs in those old versions.  Despite its *many* problems, v53 is FAR better far me than 022.

Regards,
Ray L.

460

General Mach Discussion / Re: Scripter Compile Errors

« on: December 01, 2011, 12:19:04 PM »

What version of mach3? I use an old version, and have never seen this error.

Gerry,

I couldn't tell you when this issue first cropped up, but it's been around a couple of years, since at least 3.042.022.  I'm now using 3.043.053, and have used dozens of intermediate versions.

Regards,
Ray L.