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Author Topic: Smoothstepper USS worth it?  (Read 1206 times)

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Smoothstepper USS worth it?
« on: January 08, 2019, 12:34:05 PM »
I've been wanting to start using a smoothstepper so that I can run windows 7 64 bit on my CNC machine but have some concerns about the features I may be losing if I make the switch from parallel port to Smoothstepper.

First, i'm limited to the USB version.  My CNC hardware and PC hardware, all breakout boards, pc motherboards, stepper drivers, power supplies etc are all mounted in the same mining-rig enclosure, which is mounted to the side of the CNC enclosure.  The breakout board connects to the PC motherboard via headers, and the smoothstepper would also be mounted inside the enclosure and necessarily connect to the motherboards onboard USB3.0 header.  The pc motherboard doesn't have an Ethernet header, only the plug on the rear I/O panel. 

 I'm OCD about wiring neatness, having an Ethernet smoothstepper would mean a hole drilled into the enclosure, and a wire hanging out of the hole so it could be plugged into the back of the motherboard.  Such a thing would be like having a penis growing out of my forehead. It's mere existence would be intolerable, like a snake loose in the house, I couldn't stop thinking about it until it was gone.


My biggest concern is the features I might lose switching to the smoothstepper. 

First, closed loop PID control of the spindle motor.  I've read online that USS smoothstepper in Mach3 can't do closed loop PID, or somehow, eliminates Mach3s ability to control the spindle closed loop.  Currently, my 1.1kw bldc motor, in combonation with Mach3 in closed loop PID operation holds + or - 10 rpm, even when entering and exiting cuts.  I really don't want to lose this.

Also, i've read that I will lose backlash compensation.  This isn't as big of a deal as my ballscrews have almost no backlash but I do occasionally, rightly or wrongly, use it to hit a tolerance when it's is a couple thousandths undersize or oversize.

The ability to use speed override in the positive direction. I've read that the smoothstepper won't allow feed override to increase the feed speed.

Also, I keep reading about weird reliability issues, such as losing communication between mach3 and the smoothstepper,  the smoothstepper running out of data, etc.

Are my concerns realistic? Is there a way to actually control the spindle closed loop, use the feed override and backlash compensation with the smoothstepper?

How does it cause these issues? does the smoothstepper override, ignore or otherwise not communicate some of the Mach 3 to breakout board communications?  For example, if Mach 3 is sensing rpm via the index signal, and modulating the pwm pulsewidth to adjust RPM, does the smoothstepper not communicate these instructions to the breakout board, or does the smoothstepper somehow prevent these calculations from taking place at all?
Re: Smoothstepper USS worth it?
« Reply #1 on: January 08, 2019, 03:14:27 PM »
Hi,
I use the ESS and it is much preferred, much lower latency and electrical noise immunity.

Note that I use Mach4 and cannot be 100% about one-to-one correspondence to Mach3. The Mach3 plugin having been around
for so many years is in most respects more advanced and complete than the Mach4 plugin.

The ESS has an extra port, thus has more IO. In addition to the extra port it has a bigger FPGA. The bigger FPGA allows greater
support for different features.

The ESS plugin for Mach4 has:
homing, probing, slaving, backlash comp, lathe threading, PID spindle control but does not have THC as yet, we are told that its coming.

You would need to confirm with Warp9 TD but I believe all of these features are supported in the ESS Mach3 plugin AND THC.
The USS with the smaller FPGA does not have all these features. The Warp9 TD website makes it plain that the USS does not have
backlash comp or THC. The lack of THC support is due to the electrical interference of the plasma making a USB connection just too
unreliable.

I've used the ESS for 2-1/2 years and never had it run out of data, it is in short way WAY WAY more reliable than the parallel port
it replaced.

I too have heard reports about 'run out of data errors' with not just the USS but the UC100, the 57U from Pokeys and others, ALL of them
USB connected. The Ethernet connection is very much more reliable. You may have noted that CNCDrive, the company responsible for the
UC********* products have discontinued their multiport (UC300 and  UC400) USB models and are now making Ethernet connected boards only.

Quote
I'm OCD about wiring neatness, having an Ethernet smoothstepper would mean a hole drilled into the enclosure, and a wire hanging out of the hole so it could be plugged into the back of the motherboard.
Do you prefer wiring neatness or do you prefer a reliable, working CNC solution?

Quote
For example, if Mach 3 is sensing rpm via the index signal, and modulating the pwm pulsewidth to adjust RPM, does the smoothstepper not communicate these instructions to the breakout board, or does the smoothstepper somehow prevent these calculations from taking place at all?

I cannot be sure about the USS, my experience is with the ESS. It does read the index signal and does the speed calculation in real-time. What the SmoothStepper
cannot do, neither can any external motion controller hooked to a Windows PC, is update Mach in real-time.  Windows is not a real-time system and the communication
delay make it worse. With Mach3 and USB you could be talking a 20-30 ms round trip from the controller to Mach and back again, its just too slow for a feedback
loop. The ESS enacts the spindle PID loop on the ESS board, all in real-time, it does not require intervention from Mach at all, Mach is the supervisor only.

Just as a matter of historical interest Machs parallel port is a near real-time control system, the parallel port driver lives in the kernel of the PC. The computing
world looked on in amazement when Art Fennerty produced the driver and achieved as good real-time performance as it does not withstanding its hiccups.
To my knowledge NO ONE has been able to duplicate Art's achievement.  It was Art's driver that allowed a Windows PC to be a useful and cheap CNC control
and therefore Mach to become as popular as it has.

Craig

My wife left with my best friend...
     and I miss him!
Re: Smoothstepper USS worth it?
« Reply #2 on: January 08, 2019, 03:47:08 PM »
"Do you prefer wiring neatness or do you prefer a reliable, working CNC solution?"

Without the smoothstepper, i have exactly that.

Ill consider what yove said. I have the USB smoothstepper installed and currently running a program to test it.  Everything is running very well except as predicted, the spindle speed accuracy has suffered as it is completely open loop.  It is within 40rpm though.  Everything else is great.

Ill try cutting some metal in a few minutes to see how much it bogs down the bldc motor without a pid loop.  If its too much, i can just unplug the smoothstepper and plug the parallel port back in.

The parrallel port has been running like a champ since 2014, i just thought it would be nice to run 64bit windows since my controller pc has a 64bit cpu and memory.

Im sure i could sell the USB smoothstepper on ebay and come up with a way to route the ethernet cable out and plug it into the i/o panel, that doesn't look line Fred Sanford did it.

« Last Edit: January 08, 2019, 03:49:45 PM by Ken226 »
Re: Smoothstepper USS worth it?
« Reply #3 on: January 08, 2019, 04:02:56 PM »
Hi,
well it sounds like your installation with the USS is working fine.

I think the principle determinant is whether the USB communication is adequate. There have been a few users whom have no end of trouble
with 'running out of data'  and total cessation of USB comms. It sounds if your 'electrical noise' environment is reasonably benign. That being the
case then carry on with the USB.

From your description the only feature you will really miss is the spindle  PID.

It would be possible to make a small circuit board that would add that feature....if you are into electronics. I mean not so many years ago ALL
speed control was done with analogue boards.

Craig
My wife left with my best friend...
     and I miss him!
Re: Smoothstepper USS worth it?
« Reply #4 on: January 08, 2019, 04:21:37 PM »
Thanks for the info Craig.

I lke a noise free case, i shield, use lots of twisted pairs and have a fetish for ferrite beads. I donte have any trouble with noise.

The USS is running great, your correct that ill only miss the pid. But, maybe not that much.

I just played with some 6061 using MDI.  Without pid, running at 3300rpm and 16ipm with a .375" 3 flute alu-power, i had no loss of speed using .186" stepover @ .05" doc.  I had a 10rpm loss of speed @ .375 stepover .05" doc, and a 40rpm loss of speed with a .375" stepove and .1" doc.  All running at 16ipm.

I can live with the open loop spindle.  Hell, the spindle runs smoother anyway under the smoothstepper than with pid, on the parallel port.
Re: Smoothstepper USS worth it?
« Reply #5 on: January 09, 2019, 05:33:21 PM »
Hi,
well it sounds like your installation with the USS is working fine.

I think the principle determinant is whether the USB communication is adequate. There have been a few users whom have no end of trouble
with 'running out of data'  and total cessation of USB comms. It sounds if your 'electrical noise' environment is reasonably benign. That being the
case then carry on with the USB.

From your description the only feature you will really miss is the spindle  PID.

It would be possible to make a small circuit board that would add that feature....if you are into electronics. I mean not so many years ago ALL
speed control was done with analogue boards.

Craig


I took your advice. An ethernet smoothstepper is in the mail.

After reading up on them both, i definitely want the backlash comp and PID spindle.

I ordered a mini pci-e ethernet card, which plugs into the pci-e slot and will give me an internal ethernet header, keeping all the wiring neat and clean (and noise free).
Re: Smoothstepper USS worth it?
« Reply #6 on: January 10, 2019, 01:23:06 AM »
Hi,
my OCD self (not!) congratulates you.

Did you confirm with Warp9 TD about spindle PID for Mach3? Its certainly available for Mach4 and I assume so for Mach3
but worth an email for confirmation.

Craig
My wife left with my best friend...
     and I miss him!
Re: Smoothstepper USS worth it?
« Reply #7 on: January 10, 2019, 08:26:04 AM »
I didn't confirm it via email, but i found multiple references to its existence from different sources, including some instructions on setting it up.  It only available in PWM mode, which is what my analog converter uses.
Re: Smoothstepper USS worth it?
« Reply #8 on: January 10, 2019, 10:50:11 AM »
There doesnt appear to be a way to edit previous posts here.

I've been trying to open the ess plugin in mach 3 to familiarize myself with the setup screens, but it doesnt want to open without having the ess connected. 

Is there a way?
Re: Smoothstepper USS worth it?
« Reply #9 on: January 10, 2019, 02:55:43 PM »
Hi,
you can edit posts only for a few minutes immediately after posting only. Thereafter you can not edit them.
If there is something which is badly wrong flick tweakie a PM, can edit/delete a appropriate.

The ESS plugin really requires the ESS device to be plugged in and communuicating. My  Mach4 development laptop has the
ESS plugin installed and enabled but not selected as motion device. Thus I can open and inspect the plugin but mach4
complains and whinges that the device is not plugged in.

Craig
My wife left with my best friend...
     and I miss him!