Hoss's G0704

[robcap]

Originally Posted by hoss2006 Yeah, the lag reported for the wireless ones is there with the wired one too. The MPG doesn't work like a normal MPG where the faster you spin the handle the faster the axis moves. They don't even have it set to the MPG mode, they have it set for step mode when using the MPG. One click on the MPG wheel equals whatever is set for Cycle Jog Step. If you spin too fast it easily overwhelms Mach. I scrutinized their videos and if you look close you can see the lag as they spin the handle fast, they stop spinning but the DRO keeps going a little bit. I'd avoid this one if I were you. Hoss

I was afraid of that. I have the ShuttleRU and it has the same lag issue, must be the usb driver or plugin limitation. Looks like one you have has a real rotary MPG? Why not open it up, if it has a real MPG you should be able to wire the dial directly to your breakout board.

[hoss2006]

I already have a real mpg wheel I used on the control panel before.
The main thing I was interested in was the handy little dro screen.
I might consider opening it up to do just like you said though, maybe hack their selector knob
too to actually switch between axis under mpg mode.
It does nothing in mpg mode now.
Thanks, Hoss

[Connor9220]

Originally Posted by hoss2006 Yeah, the lag reported for the wireless ones is there with the wired one too. The MPG doesn't work like a normal MPG where the faster you spin the handle the faster the axis moves. They don't even have it set to the MPG mode, they have it set for step mode when using the MPG. One click on the MPG wheel equals whatever is set for Cycle Jog Step. If you spin too fast it easily overwhelms Mach. I scrutinized their videos and if you look close you can see the lag as they spin the handle fast, they stop spinning but the DRO keeps going a little bit. I'd avoid this one if I were you. Hoss

Problem isn't the wireless/wired.. It's the fact that it's USB and thus, not real time. I built my own MPG for my Router... Basically I used a Hybrid approach (I Use EMC not Mach 3). The MPG itself is wired directly to the Parport pins for input. The rest of the unit is serial based via a USB serial port. This allows me to do Cycle Jogging, and the faster I spin the MPG the faster the machine moves. The serial link is used to send the buttons and receive updates from EMC for the onboard DRO-- Oh, and mine can do both mm and inch display! Mine is still in prototype stages and is kinda bulky. I plan to mount it in a nice small case similar to what they have theirs done in. I had also debated on using a hard wired E-Stop using 2 free wires in the cable or use software E-Stop. I decided on hard wired to the parport instead of relying on the serial to transmit the E-Stop command. The cable is a CAT-5 Ethernet cable. 2 wires for the MPG, 4 For USB (Including power and ground), Leaves 2 for the E-Stop. I'll have a shunt I can plug into the jack that will tie the E-Stop lines together in case I need to use the machine without the DRO.

Thanks, Billy

[Signal9]

This is the one I got from Ebay and it uses the Serial port for its commands and USB for the power only.

New MACH3 CNC Electronic Hand Wheel Only For ModsMach3 Engraving Machine Pulser | eBay

It has no DRO display so its a apple vs orange comparison.

[rpovey]

Originally Posted by Connor9220 Problem isn't the wireless/wired.. It's the fact that it's USB and thus, not real time. I built my own MPG for my Router... Basically I used a Hybrid approach (I Use EMC not Mach 3). The MPG itself is wired directly to the Parport pins for input. The rest of the unit is serial based via a USB serial port. This allows me to do Cycle Jogging, and the faster I spin the MPG the faster the machine moves. The serial link is used to send the buttons and receive updates from EMC for the onboard DRO-- Oh, and mine can do both mm and inch display! Mine is still in prototype stages and is kinda bulky. I plan to mount it in a nice small case similar to what they have theirs done in. I had also debated on using a hard wired E-Stop using 2 free wires in the cable or use software E-Stop. I decided on hard wired to the parport instead of relying on the serial to transmit the E-Stop command. The cable is a CAT-5 Ethernet cable. 2 wires for the MPG, 4 For USB (Including power and ground), Leaves 2 for the E-Stop. I'll have a shunt I can plug into the jack that will tie the E-Stop lines together in case I need to use the machine without the DRO. Thanks, Billy

The issue is going to be the implementation of the Mach driver, any delay from the USB connection should be measurable in the uSec's.

Your not going to be able to turn the wheel fast enough to flood the connection, so it's likely backing up when the mach side driver drains them out of whatever queue they're being stuffed into, and converting them to step commands. I'd bet the authors took the easy way out and just convert the pulses to key presses, which in turn queue up and cause the lag.

You should be able to fix it with software, of course without the source code to the existing driver or documentation, it's probably more work than it's worth.

[FannBlade]

Originally Posted by Signal9 This is the one I got from Ebay and it uses the Serial port for its commands and USB for the power only. New MACH3 CNC Electronic Hand Wheel Only For ModsMach3 Engraving Machine Pulser | eBay It has no DRO display so its a apple vs orange comparison.

Nice price on that unit. Does it work ok? Did Mach 3 recognize it?
Now I need to see if my MB has serial port.

[HimyKabibble]

Originally Posted by rpovey The issue is going to be the implementation of the Mach driver, any delay from the USB connection should be measurable in the uSec's. Your not going to be able to turn the wheel fast enough to flood the connection, so it's likely backing up when the mach side driver drains them out of whatever queue they're being stuffed into, and converting them to step commands. I'd bet the authors took the easy way out and just convert the pulses to key presses, which in turn queue up and cause the lag. You should be able to fix it with software, of course without the source code to the existing driver or documentation, it's probably more work than it's worth.

"The issue is going to be the implementation of the Mach driver, any delay from the USB connection should be measurable in the uSec's." - Not true. USB operates on 1 mSec frames, and any particular data packet may well have to wait for the next frame. That gets the data to the hub on the PC, which is the fast part. Next, the Windows driver needs to service the huib, pick up the data, and notify the application that new data has arrived. That can EASILY take 10mSec or more, with spikes MUCH longer than that when the system is busy.

Bottom line is you simply can't sent quadrature signals across USB and expect a good result. There are two "right" ways to implement an MPG for Mach3:

1) Connect the MPG quadrature signals directly to the PC, or the motion controller, if you're using one. For the simplest "dumb" pendants, like my iMach Pro, this is really the only option. If you're using a motion controller, it is really best to connect the pendant directly to the motion controller, and let its processor perform the jog entirely internally. This is how the SmoothStepper, KFlop, and others operate - the motion controller does the jogging, and sends Mach3 position updates along the way.

2) Have the pendant monitor the MPG quadrature lines, and accumulate a count (effectively, a commanded position), based on the quadrature changes. Then, periodically (10 or more times/second), pass that count to Mach3. This is how good USB, serial, and ModBus pendants operate, and they will perform *almost* as well as one connected directly to the PC or motion controller.

Incredible that those guys would sell a pendant with only two digits right of the decimal point. It should be a trivial firmware change to fix that, so hopefully they will do so.

Regards,
Ray L.

[hoss2006]

Originally Posted by Signal9 This is the one I got from Ebay and it uses the Serial port for its commands and USB for the power only. New MACH3 CNC Electronic Hand Wheel Only For ModsMach3 Engraving Machine Pulser | eBay It has no DRO display so its a apple vs orange comparison.

Yeah I'll probably wind up doing something like that and run another cable
to connect the MPG and selector switch to the bob and keep the usb
for the DRO and other buttons.
The other buttons are still quite useful and can be reassigned.
Hoss

[LacL]

Hi Hoss, I'm a long time lurker here and wanted to say Thank You for all you do. Every time I think I'm done with mods to my CNC, you come up with something new and think to myself I must have that.

When I upgraded my mobo and couldn't get the lpt card to work with my mpg, I decided to convert it to USB and wrote my own MACH plugin for it.

I used the sample code provided with the SDK and there are basically 2 modes you can run the mpg inputs as, incremental mode (step) or jog mode (MPG).

Incremental mode seems to use a buffer or queue so this is what is causing delays afaik. Never figured out how to make the engine read the queue faster. There's unfortunately no documentation on how all the MACH internals work that I could find so I was on my own to figure this stuff out.

Jog mode has no discernible delays and I can even move the table precisely in single steps if I run the mpg dial slowly. I hardly ever use it in incremental mode anymore as a result. The delays are definitely not caused by the USB comms rate.

Maybe you can ask these guys to implement a jog mode in addition to the incremental mode they seem to be using in their plugin. That should eliminate all delay issues. Adding decimal places to the display would require a firmware update though. I hope they had the foresight to implement a boot loader for that.

[hoss2006]

Thanks LacL,
Jog mode with this pendant doesn't do anything useful, each click on the MPG acts
like you just tapped the jog button on the keyboard.
Basically just like step mode except that in one direction it keeps jogging until you reverse the MPG.
Not of much use especially at rapid speed, it feels like a runaway.
They have work to do to make this really useful.
Hoss

[wfbrown53]

Hoss, is your CNC setup with Mach3 using the parallel port to the controller or does it use some other communications protocol more up to date. I have Win7 64bit and am looking at controller options with Mach3 since the parallel port does not work with Mach3 and 64bit Win7.

[hoss2006]

Originally Posted by wfbrown53 Hoss, is your CNC setup with Mach3 using the parallel port to the controller or does it use some other communications protocol more up to date. I have Win7 64bit and am looking at controller options with Mach3 since the parallel port does not work with Mach3 and 64bit Win7.

Yes I'm using XP so parallel port support is no problem.
Win 7 64bit will need something like the smoothstepper which is USB.
Hoss