Messages

41

Mach4 General Discussion / Re: false signals from clearpath enable

« on: March 16, 2020, 09:04:40 AM »

Sounds like it could be electrical noise, although your filtering should have cleared that up. Do you have access to an oscilloscope? They are invaluable for capturing short and intermittent events like that.

Can you verify that your Clearpath motors and your motion controller share the same DC common potential?

42

Mach4 General Discussion / Re: Mesa FPGA cards

« on: March 16, 2020, 08:58:59 AM »

I'll add a short tagline onto this. Most modern position servos close the position, velocity, and torque feedback loops at the motor controller (servo drive). 20 years ago, almost all servos were analog velocity or torque controlled and required a position controller separately. This got many people in the mindset (even to this day) that a closed loop motion controller is necessary or even beneficial.

Now there are a few cases where it is. Mainly these are software features like rigid tapping or threading on the lathe which requires axis synchronization to an external encoder. The other case would be using dual feedback (motor + load). This allows the control system to compensate for mechanical errors such as screw lead and backlash by direct measurement of the final actuator. The latter example is even incorporated into a handful of higher end servos as Craig mentioned.

The point I'm making is that if closed loop positioning is what you are going for, there are fully functional, inexpensive, and easy to integrate control methods which work with Mach 4 today and do not require Mach 4 to act closed loop. Many other features can be made closed loop at the motion controller (i.e. Ethernet Smoothstepper THC or PID spindle). Mach 4 being buffered isn't as big of a deal as many make it seem.

43

Mach4 General Discussion / Re: Mach4 positioning error

« on: February 21, 2020, 11:24:58 AM »

Perfect!

I bet you could use it without the converter to be honest, but it would be more susceptible to issues with noise.

Mach 4 also has screw mapping which could be useful for you using these scales. You can fix lead and cyclic error, but not backlash or mechanical inaccuracy.

Mike

44

Mach4 General Discussion / Re: Mach4 positioning error

« on: February 21, 2020, 09:49:28 AM »

I had to dig deeper on that encoder. Let me revise my earlier comment. Based on this data sheet from Mitutoyo (https://www.mitutoyo.com/wp-content/uploads/2012/11/E4189-539_579NC_Scale.pdf), the encoder outputs EIA RS-422A which is compatible with FANUC controls using quadrature counting with serial backup and absolute positioning.

It seems you can use pins 1-7 on the connector to read the scale as a traditional differential quadrature encoder (compatible with ESS), however you will not be able to interface with the serial connections without some special effort and custom interfaces. Without the serial data, this encoder is no longer absolute, but remains fully functional as incremental.

The FANUC control that this encoder is designed for would read the serial data at startup to get the absolute position of the scale, and then use the quadrature signals afterwards to count pulses. Every so often it will query the serial channel to make sure that the position that it has counted to matches what the encoder thinks is right. Any error here would trigger an alarm.

I would still think that a more traditional encoder such as the Mitutoyo AT202 (identical in size to your selected AT332) or the AT211 (smaller in cross section and available in higher resolution) would be the best choice since you won't be able to use the serial channels of the AT332 anyways. I bet they are less expensive too.

You will need a differential to single ended receiver, but I would check to make sure the CNC4PC is going to be fast enough for your application (email them since it is not published). The resolution x travel speed of your scale will set the output frequency. This must be lower than the capacity of the chip they use on their converter.

With the information posted above, you will not require any boards from pico-systems as all the encoders we are looking at output quadrature signals. Those boards would be used if conversion from another type of feedback was required.

Lets make sure we are on the same page before you go buy stuff. I don't want to mislead you here.

Mike

45

Mach4 General Discussion / Re: Mach4 positioning error

« on: February 20, 2020, 09:40:45 AM »

Hakan,

Thanks for getting back to us with the root cause of your issue!

You should be able to read encoders into Mach 4 given you have enough pins and your BOB supports it.

The ESS is able to use all inputs for encoder input as far as I know. The one limitation is that you must use single ended quadrature encoders. The ones you linked look to be FANUC output which wouldn't work directly. There are some companies which sell converters for converting SIN/COS, LVDT, resolver, or other types of feedback to quadrature, but they are not super cheap.

I'd recommend finding encoder that directly output quadrature (5V TTL), however here are some links for converter boards if you prefer to go that route.

http://www.pico-systems.com/resolver.html

http://pico-systems.com/osc2.5/catalog/product_info.php?products_id=33&osCsid=qgn1d3kdkqc3v8b254gs00sj51

http://pico-systems.com/osc2.5/catalog/product_info.php?products_id=27

https://www.vegacnc.com/hardware/resolver-to-encoder-w-hall-din-panel-mount/vega-2790502/

Mike

46

Mach4 General Discussion / Re: Integrating Clearpath SD Motors With Mach4

« on: February 13, 2020, 11:17:01 AM »

Can we all just take a moment to appreciate companies taking the time to offer service to their customers on online forums? Bravo!

47

Mach4 General Discussion / Re: Integrating Clearpath SD Motors With Mach4

« on: February 11, 2020, 09:11:58 AM »

The servo will ideally ALWAYS be within the error window and thus having a 'move complete' or 'in final position' signal is superfluous.

I do a lot of non-CNC motion control systems using some high end servos for work. It is actually quite common to incorporate an "in position" bit to wait for the axis to accurately locate itself before triggering the next move. Often your position error tolerance (before fault) is opened wider than your desired accuracy for each move. Giving the axis time to finish a move allows the servo system to correct for any lag in the response.

It is important to include a position timeout in these cases. If the axis were to jam, it would be programmatically stuck waiting for it to complete the move. A maximum move timeout would stop motion in this case.

Did you run the Clearpath auto tune once your mechanics were setup, to get the servo tuned to YOUR setup?

This is totally right here. It even should be tuned under load if possible.

One last thing. On machines, mechanical problems are the source of servo troubles probably 60% of the time. Make sure you don't have lash in the drive train or the machine is flexing or deforming under load.

48

Mach4 General Discussion / Re: What did I do wrong?

« on: February 04, 2020, 01:13:30 PM »

Yeah, I do the same. Have a custom profile for my machine with all the settings and such. Thought it should just copy over no big deal?

49

Mach4 General Discussion / What did I do wrong?

« on: February 04, 2020, 11:50:35 AM »

Hi All,

I was in need of re-imaging my CNC PC with a fresh copy of Windows 10 due to some USB driver issues. Planning ahead to make this as painless as possible, I created an "installation" USB that had all the .exe files I needed as well as any documents that needed to be transferred.

To set up Mach 4 again, I downloaded a new .exe file and copied my profiles, screensets, and modules to the USB drive. I also downloaded new copies of the ESS plugins and Warp 9 SCU.

When the imaging was complete, I installed Mach 4, copied my profiles into the profiles folder, screensets into the screens folder, modules into the modules folder, and plugins into the plugins folder. When I opened Mach, I was disappointed to find that all of my settings under Control and Plugins -> Warp 9 ESS were completely blanked out. I thought the settings would be transferred with the profile.

Fortunately I made screenshots of all the configuration screens so it won't be much work to redo them, but what did I do wrong? How do you transfer the settings?

Thanks,

Mike

50

Mach4 General Discussion / Re: Mach 4 Feature Request

« on: January 15, 2020, 11:30:10 AM »

Feature request for a graphic element which allows you to display a trend/graph/chart of data, perhaps loaded from an external log file. This would give users a ton of flexibility to add info to the screens.

Example usage:
-Time series data plotting (spindle load, axis position, etc)
-Probing X,Y point display
-Cycle Time history