Bridgeport/Romi EZPath S Retrofit Planning

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30 Dec 2021 04:02 #230313 by TurboStreetCar
Ah ok!

Thanks, i thought i remembered seeing the "following" error in the INI files.

The thing about these handwheels are they are more designed to mimic mechanical handwheels, so they have increment scales, but no detents or notches. They turn smoothly as to dial in an exact position, instead of dialing in "steps" like on a typical MPG, like on my HAAS TM-1P. These, you turn them the amount you want to move, whether its 10" or 0.0001". They are also 6 wire encoders, so it would need three channels per encoder. They're 600ppr.

One other question, The EZPath, has these functions, where you can pick say "Chamfer". When active, it links the X and Z axis, to ONE handwheel, So they both move together, to cut a 45 degree chamfer.

There are other functions that make the axis move together at a specified angle, or radius, or other type of linked movement.

Is it possible to do something like this in software in Linuxcnc?

Thanks,
Dan

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30 Dec 2021 13:02 #230334 by tommylight
Sounds like normal encoders, MPG encoders always have detents and have 25 to 100 PPR.
And i am pretty sure it can be made to move 2 or 3 axis at the same time with some hal programming.

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30 Dec 2021 14:25 #230339 by TurboStreetCar
Yes, I do believe they’re standard encoders for the hand wheels.

Reflecting on my new revelation that these servo drive are currently configured for analog control, would I be better off getting the 7i97 instead of the 7i95?

This would give me the same 6 encoder inputs and servo outputs, but I could use one of the analog outputs (I believe) for spindle control, eliminating the need for the PWM converter.

The cost is about the same for a 7i97 vs the 7i95+PWM converter.

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30 Dec 2021 14:29 #230341 by tommylight
I would go for the 7i97, just keep in mind it does requre further tuning in LinuxCNC, while step/dir and 7i95 leave that on the drives itself.

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31 Dec 2021 05:29 #230378 by TurboStreetCar
Hmm, I will need to connect my laptop to the drives to change parameters in order to run them in Step/Dir.

But then again, the tuning programmed into the drive, I assume, would be already configured for analog torque/speed control mode. So switching them to step/dir would likely require retuning the drives PID's.

I think running them, as is, in analog would be better off. Id like to keep the re-engineering to a minimum as its already a functional system, not a new build.

Another quick question, as I'm finding it somewhat difficult to nail down. IF i wanted to add I/O to the 7i97 card, I would use a 7i50? or a 7i37? Is there a cheaper input/output expansion?

I would connect the 7i50 or 7i37 to the 7i97 using a 50pin flat cable? Is that a standard 50 pin IDC cable/connectors?

Thanks so much!

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31 Dec 2021 12:43 #230386 by tommylight
Double check this, but i think 7i97 should have a free SSerial port (7i77 has one), so a Mesa 7i84 can be wired directly through a cut down ethernet cable, no flashing required, gets you 32 inputs and 16 outputs.
Cabling instructions are in the manual.

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31 Dec 2021 13:55 #230389 by TurboStreetCar
Ah! Yes it appears the rs-422 header is what i would use for that. That's pretty convenient.

Im going to try to get my laptop to connect to the servopack and save the parameter files so i can see exactly how the drives are configured.

I like the simplicity of step/dir control, but I have to imagine, if the original machine used analog control signals, there must be a reason. Unless its just age and technology.

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03 Jan 2022 16:12 #230662 by TurboStreetCar
Upon further research, I've found this article from Centroid on using Yaskawa Sigma 1 series drives/servos.

Centroid Yaskawa Instructions

Per their instructions, they recommend using Step/Direction over analog velocity control modes.

They also don't use host encoder feedback, Instead letting the drive do all of the PID control.

I think this is the direction im going to go, Which means ill be using a 7i95 board with PWM->Analog Add on for VFD control.

However, I WILL wire in the encoder feedback as i want to be able to home both axis to the encoder index position, This way my home position is accurate to encoder position, rather then the home switch position. I Believe this will allow better power on position repeatability. I Will just set the Linuxcnc PID to effectively a "0" value so it just outputs the raw position to the drives.

Im just waiting on some components so i can pull the parameters from the drives and do some checking/testing.

Ill also likely use a 7i84 for I/O expansion at some point. But for now, i think the 7i95 may have JUST enough I/O for what i need.

Id also be interested in hooking up the drive load meters. Not sure ive seen anything in linuxcnc about axis load meters. Going to look into that now.

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11 Jun 2022 18:52 #244948 by TurboStreetCar
Well, Been a little while. 

Ive done some more thinking and some more research.

Ive purchased a 7i97 and a 7i84, and i have began playing with them to test some functions and gain some familiarity. 

So far, ive gotten my config files (i think) set up correctly. Ive tested the two axis outputs, spindle outputs, and one input on the 7i97 card. Im still trying to figure out if some offsets are required for the axis outputs. It seems, as soon as X or Z is enabled, the drive is automatically at 9.99V, instead of 0V. 

This i believe could be from the PID loop, but im not sure. I also have no encoders hooked up, so to test ive had to enter extremely large following errors allowance. BUT, with that said, i do see the voltage change when jogging, so i know im on the right path.

The spindle analog output is working correctly, and when i trigger the input for second gear, the voltage scales correctly down, which seems to be working perfectly.

Ive decided to go with the 7i97 and maintain velocity mode/analog control of the Yaskawa Sigma 1 drives as thats how the machine was already set up, and i wanted to change the least amount possible to get it retrofitted. How i wanted to arrange this, would require wiring in encoder feedback to the 7i97 anyway, for the homing index, so ill be attempting to tune the PID for good movement when i get it set up.

I believe i will start a new thread with progress on the actual retrofit, and im going to make some youtube videos documenting the process, which will be posted in the new thread.

I appreciate the help ive received thus far and im pretty excited to get this retrofit done.

Thanks so much!

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11 Jun 2022 21:26 #244956 by tommylight

It seems, as soon as X or Z is enabled, the drive is automatically at 9.99V, instead of 0V. 

That is pretty much normal with no feedback from the encoders.
Not sure, but setting the P value to 0 should stop that from happening, or maybe there are other values. I never tried this, i always wire encoders first, then enables, then analog, testing each stage separately.

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