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Re: Newbie converting a PM-728VT

Posted: Sat Jan 09, 2021 12:40 am
by DesertRider
It was one of the NEMA23 motors (I have two NEMA 23s and one 34). While the x-axis motor was working well, the y axis would not respond to commands from Acorn. I could spin it with the Teknic MSP software, and it had the flashing green light; it wasn't a cable issue or Acorn issue becasue switching those around localized the pb to the motor. I downloaded the configuration of the other (working) motor, and uploaded it to the motor in question, and the engineer from Teknic walked me through the steps in the MSP software and after rebooting the system it worked. I frankly am not sure what made it worked but am glad it is fine now. Must point out the tech support person was genuinely very helpful.

Re: Newbie converting a PM-728VT

Posted: Sat Jan 09, 2021 12:44 am
by DesertRider

Re: Newbie converting a PM-728VT

Posted: Sat Jan 09, 2021 10:20 am
by martyscncgarage
Something must have been misconfigured. But glad you got it going.
Hope you can share exactly how you have them wired. Seems as though some stumble in getting SDSK's going

Marty

Re: Newbie converting a PM-728VT

Posted: Thu Jan 14, 2021 12:16 am
by DesertRider
Great idea Marty, I will share here what I did thus far. I assume the Acorn board and its computer connection have successfully been bench tested. Before wiring Clearpath motors to the Acorn, one should set them up using Teknic's MSP setup software. You should download the Teknic user manual and read it, then follow along.

For power supply I used the factory IPC5 and power hub (the IPC5 only allows 2 motors, the power hub increases that to 4), and the factory cables. The Acorn power supply is limited in output, and the hub (as well as sundry bits and parts like contactor, proximity sensors etc) need a 24V input, so I replaced the acorn PS with a MeanWell DIN-rail mounted PS that has sufficient amps.
IMG_6834.JPG
The main setup is straightforward. First, decline "auto-tune" -- that will be done once the motors are running and are connected to the hardware of the mill. Just run it with "no load" to make sure it plays well with Acorn. Then configure the steps to 6400 and RAS to 16 ms.
MSP configure_small.png
Once the motors can be spun in MSP you can connect them to the Acorn. It is not necessary to disconnect the USB connection while the motors are connected to the Acorn. This point was helpfully clarified for me by a Teknic engineer (thank you Jon!) with whom I talked on the phone last Friday. The MSP scope and other diagnostics are designed to be used in real-time while the motor is working.

For the Acorn connection, I cut off the board-side (not the overmolded end) Molex pin. This way I connected the wires directly as in this photo:
Acorn wiring.png
For each motor the order is: 1=yellow, 2=brown, 3=orange, 4=red. The green wires from each motor get connected together to Acorn's Motor OK input. Each motor still has a white, a blue, and a black wire -- these get connected together to + 24V. For the real setup on the mill, I will use aviation style connectors; one needs only 6 pins (the 3 wires I just mentioned can be collapsed onto one pin), but using an 8-pin connector may be cleaner.

In the end it should look like this:


Re: Newbie converting a PM-728VT

Posted: Thu Jan 14, 2021 11:18 am
by martyscncgarage
Desert Rider,
Thanks so much for sharing your recipe! Did you use the Centroid Clearpath schematci?

Re: Newbie converting a PM-728VT

Posted: Mon Feb 01, 2021 9:20 am
by DesertRider
martyscncgarage wrote: Thu Jan 14, 2021 11:18 am Desert Rider,
Thanks so much for sharing your recipe! Did you use the Centroid Clearpath schematci?
Essentially yes.

I wonder how can I wire in 6 inputs for the limits (X+, X-, Y+, etc). I'd much rather do it separately than to wire sensors in series. Does the Acorn allow that? I don't see how it could accommodate that many inputs, but I might be missing something. Thank you.

Re: Newbie converting a PM-728VT

Posted: Mon Feb 01, 2021 9:29 am
by martyscncgarage
DesertRider wrote: Mon Feb 01, 2021 9:20 am
martyscncgarage wrote: Thu Jan 14, 2021 11:18 am Desert Rider,
Thanks so much for sharing your recipe! Did you use the Centroid Clearpath schematci?
Essentially yes.

I wonder how can I wire in 6 inputs for the limits (X+, X-, Y+, etc). I'd much rather do it separately than to wire sensors in series. Does the Acorn allow that? I don't see how it could accommodate that many inputs, but I might be missing something. Thank you.
Current Acorn hardware has limitations of 8 inputs and 8 outputs. That is the problem. Using an external relay board is the only solution at this time.
You take the relay board and wire all the relays in series. Each CP motor connects to the input for its fault output. IF any of the motors fault it opens the series circuit. One end goes to COM and the other to an input and is assigned Drive Fault.

Marty

Please help me choose proximity sensors.

Posted: Sun Feb 14, 2021 12:17 am
by DesertRider
I have finally received the mill (2-1/2 months after ordering it) and have taken it apart to do the conversion. Please help me choose induction proximity sensors. I do have no name sensors off eBay that work with the Acorn bench test, but I want to install quality sensors as a "do it once, do it well" process. I ordered a set of Contrinex off AutomationDirect.com, but their operation does not match the Acorn's needs.

Here are the no name ones that DO work:
cheap NO prox sensor.jpg
This is the Contrinex that does NOT work: inductive proximity sensor, tubular, 12mm diameter x 60mm body, nickel-plated brass housing, PNP, N.C. output, 4mm sensing distance, non-flush, 2 kHz switching frequency, IP67, 4-pin M12 quick-disconnect.
IMG_7091.JPG
Can you please advise which model of Contrinex (or other quality brand) I should get? I noted the chinese ones are NPN NO, but I thought the Acorn wants NC sensors. Should I get NPN NOs in Contrinex? I already have the m12 wires so would prefer to stick to that size. Thank you.

Re: Newbie converting a PM-728VT

Posted: Sun Feb 14, 2021 12:00 pm
by martyscncgarage
I would use NPN NC sensors.
What you choose is up to you....
Have you looked at this page? https://www.centroidcnc.com/centroid_di ... _gear.html
Marty

Re: Proximity sensors

Posted: Sun Feb 14, 2021 5:51 pm
by cncsnw
Just get the NPN version of the Contrinex sensor.

If you are combining limits with an intermediate relay board, then the choice of N.O. or N.C. hardly matters.

Ideally you want limits to be N.C. circuits: circuit closed when all is well, circuit open when the machine moves beyond its limit. This is "fail safe" design.

However, what type of sensor gives you that behavior depends on what you have it detecting. If the sensor detects a raised surface that only arrives when the limit is reached, then ideally you would use an N.C. sensor. If the sensor detects a continuous surface that ends when the limit is reached, then an N.O. sensor would give you the behavior of an N.C. limit circuit.

There is understandably some confusion about what "normal" means in "normally-open" and "normally-closed". When you take a switch or sensor out of its package and set it on your desk, that is the "normal" condition, as far as the manufacturer's catalog is concerned. "Normal" means not activated.

If you install a switch or sensor or relay in your control system, and design the control system so that the device is activated most of the time during normal machine operation, that does not change the nature of the switch or sensor. It is still what it said on the package. So, in the example above -- using an N.O. proximity sensor to detect the face of your mill table, until you "fall off" the end of the mill table at the limit of travel -- it is still an N.O. proximity sensor. It is just providing an input circuit that is closed during normal operation, and open at the limit.