New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

All things related to the Centroid Acorn CNC Controller

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carboncymbal
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by carboncymbal »

martyscncgarage wrote: Thu Feb 18, 2021 10:48 am
Gary Campbell wrote: Thu Feb 18, 2021 12:38 am Marty...
Even tho I have the branded Molex crimper for Mini fit Jr connectors, sign me up for the terminal version
I'll let you all know what shakes out...
Marty

That is great to hear, I may try using the CNC4PC board when they release it. They indicated to me that it might be available within a 3-4 weeks.
Gary Campbell
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Location: Marquette, MI
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by Gary Campbell »

Please note, that like some others, I am a bit hesitant to use these boards until a proper solution to secure them is in hand.
GCnC Control
CNC Control & Retrofits
https://www.youtube.com/user/Islaww1/videos
martyscncgarage
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Location: Mesa, AZ

Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by martyscncgarage »

Gary Campbell wrote: Fri Feb 19, 2021 10:46 am Please note, that like some others, I am a bit hesitant to use these boards until a proper solution to secure them is in hand.
Would be nice if one of are users proficient with CAD and 3D printing could design and make some brackets for it.
Anyone? Anyone? :D
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
martyscncgarage
Posts: 7489
Joined: Tue Mar 28, 2017 12:01 pm
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Location: Mesa, AZ

Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by martyscncgarage »

Google photo album with RANDOM pictures of the build:
https://photos.app.goo.gl/oeiB95hTqhWyj1mMA
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
Gary Campbell
Posts: 1443
Joined: Sat Nov 18, 2017 2:32 pm
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CNC Control System Serial Number: Acorn 238
Location: Marquette, MI
Contact:

Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by Gary Campbell »

Would be nice if one of are users proficient with CAD and 3D printing could design and make some brackets for it.
Anyone? Anyone
Wouldn't this be most beneficial to the product supplier? To ensure that their product is properly mounted and doesn't break with normal use
GCnC Control
CNC Control & Retrofits
https://www.youtube.com/user/Islaww1/videos
teknic_servo
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by teknic_servo »

"Interesting that they don’t require resistors on this yet they do normally. Can anyone explain why that would be?"

carboncymbal,

Not sure if you say this post on a different thread so I added it here to ensure coverage.

All-
I’m an engineer at Teknic and came across your comment about step input timing errors and noise interference.

The ClearPath motor inputs are optically isolated and current limited. This design provides exceptional noise immunity even in the most difficult EMI environments like plasma CNC machines and applications that use a VFD. The optical isolation hardware of the ClearPath motors provide enough noise immunity that shielded and twisted pair cables between the CNC motion controller and the ClearPath motor are not required.

You might wonder, “if the noise immunity of the ClearPath motors is so good, then why is there a possibility of getting step input timing errors and why are the termination resistors required?” Great question!

The minimum length of time for a step to be “on” is 715ns. In addition, the minimum length of time for the “off” period between steps is also 715ns. The ClearPath “step input timing error” occurs when the “on” time of a step is shorter than 715ns, and/or the “off” time between steps is shorter than 715ns.

Typically this error is elicited when one or more of the following conditions occur:

- The controller has open collector outputs and the resistors specified in the ClearPath manual are not installed correctly, or not at all. Here is a link to the fractional hp ClearPath manual:(https://www.teknic.com/files/downloads/ ... manual.pdf)
An open collector output “drives” the signal to a true logic state but then the return signal “floats” back to its false logic state. This floating nature of the open collector signal means that the signal might not be “off” for at least 715ns required between steps before the next step is sent. This behavior is often exacerbated by capacitance in the control system, whether due to long cable runs or the electrical design.

The Centroid Acorn uses 24VDC open collector outputs, so installing 10k ohm resistors across both the step and direction outputs for each axis of motion is appropriate. This resistor promptly drives the signal to an “off” state between steps. In contrast, a driven TTL signal (this is a different hardware architecture than open collector signals) is less prone to this behavior because the circuitry “drives” the signal to ”on” and then “drives” the signal back to ”off”. This type of signal is referred to as a “driven signal”.

- The controller output voltage is lower than the minimum 4VDC required for the ClearPath motor and is unable to reliably turn on the optical isolated inputs. For example, some controllers only output a 3.3VDC signal.

- The controller's maximum step pulse output frequency is higher than 700kHz, or the step pulse time is less than 715 nS. These settings are typically configurable in the controller.
(https://www.teknic.com/files/downloads/ ... om=100,0,0)

- Shared return paths for outputs. The V+ and GND wires for each controller output should travel the entire distance from the controller to the motor and then back to the controller. Some systems have limited I/O connections so the output signals go individually out to the motor, but then they share a common return path back to the controller. For example, three output signal wires could go out to the motor but then the return wires are tied together and only one return wire comes all the way back to the controller. This can cause problems related to noise immunity.

As a side note, we’ve recently reviewed the Acorn schematics with Centroid and they will be updating their schematics to include this 10k termination resistor. This should address the issue that you mentioned.

I hope this helps you and other users. If you have any other questions regarding the ClearPath motors, please feel free to use Teknic’s "Contact Us' form (https://www.teknic.com/contact) or give us a call at 585-784-7454.

Best regards,
Tom T. - Teknic Servo Systems Engineer
tkbot47
Posts: 133
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by tkbot47 »

teknic_servo wrote: Fri Feb 19, 2021 5:40 pm "Interesting that they don’t require resistors on this yet they do normally. Can anyone explain why that would be?"

carboncymbal,

Not sure if you say this post on a different thread so I added it here to ensure coverage.

All-
I’m an engineer at Teknic and came across your comment about step input timing errors and noise interference.

The ClearPath motor inputs are optically isolated and current limited. This design provides exceptional noise immunity even in the most difficult EMI environments like plasma CNC machines and applications that use a VFD. The optical isolation hardware of the ClearPath motors provide enough noise immunity that shielded and twisted pair cables between the CNC motion controller and the ClearPath motor are not required.

You might wonder, “if the noise immunity of the ClearPath motors is so good, then why is there a possibility of getting step input timing errors and why are the termination resistors required?” Great question!

The minimum length of time for a step to be “on” is 715ns. In addition, the minimum length of time for the “off” period between steps is also 715ns. The ClearPath “step input timing error” occurs when the “on” time of a step is shorter than 715ns, and/or the “off” time between steps is shorter than 715ns.

Typically this error is elicited when one or more of the following conditions occur:

- The controller has open collector outputs and the resistors specified in the ClearPath manual are not installed correctly, or not at all. Here is a link to the fractional hp ClearPath manual:(https://www.teknic.com/files/downloads/ ... manual.pdf)
An open collector output “drives” the signal to a true logic state but then the return signal “floats” back to its false logic state. This floating nature of the open collector signal means that the signal might not be “off” for at least 715ns required between steps before the next step is sent. This behavior is often exacerbated by capacitance in the control system, whether due to long cable runs or the electrical design.

The Centroid Acorn uses 24VDC open collector outputs, so installing 10k ohm resistors across both the step and direction outputs for each axis of motion is appropriate. This resistor promptly drives the signal to an “off” state between steps. In contrast, a driven TTL signal (this is a different hardware architecture than open collector signals) is less prone to this behavior because the circuitry “drives” the signal to ”on” and then “drives” the signal back to ”off”. This type of signal is referred to as a “driven signal”.

- The controller output voltage is lower than the minimum 4VDC required for the ClearPath motor and is unable to reliably turn on the optical isolated inputs. For example, some controllers only output a 3.3VDC signal.

- The controller's maximum step pulse output frequency is higher than 700kHz, or the step pulse time is less than 715 nS. These settings are typically configurable in the controller.
(https://www.teknic.com/files/downloads/ ... om=100,0,0)

- Shared return paths for outputs. The V+ and GND wires for each controller output should travel the entire distance from the controller to the motor and then back to the controller. Some systems have limited I/O connections so the output signals go individually out to the motor, but then they share a common return path back to the controller. For example, three output signal wires could go out to the motor but then the return wires are tied together and only one return wire comes all the way back to the controller. This can cause problems related to noise immunity.

As a side note, we’ve recently reviewed the Acorn schematics with Centroid and they will be updating their schematics to include this 10k termination resistor. This should address the issue that you mentioned.

I hope this helps you and other users. If you have any other questions regarding the ClearPath motors, please feel free to use Teknic’s "Contact Us' form (https://www.teknic.com/contact) or give us a call at 585-784-7454.

Best regards,
Tom T. - Teknic Servo Systems Engineer
Tom,
Thanks for the lucid explanation. I have been using Clearpath motors on my CNC tool now for about a year, and am using 1K termination resisters for longer cables, because that is what was recommended at that time. I don't believe I've been getting any errors using the 1K. Now that you are recommending 10K, do we need to go back and switch to 10K, or is 1K good enough? Has something changed in the driver circuit that drove 10K?
Thanks,
Tom
teknic_servo
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by teknic_servo »

Tom K,
It comes down to the current rating of the resisitors. The 1k ohm resistor used with 24VDC at a high duty cycle could get warm to hot. If you have run your system for a substantial period of time and do not see any heat related issues with the resistors, you could be fine. That said, it would be safer in the long run to change the resistors to 10k ohm.
Thanks,
Tom T
tkbot47
Posts: 133
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CNC11: Yes
CPU10 or CPU7: No
CNC Control System Serial Number: haven't installed CNC12 yet

Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by tkbot47 »

teknic_servo wrote: Tue Feb 23, 2021 12:23 pm Tom K,
It comes down to the current rating of the resisitors. The 1k ohm resistor used with 24VDC at a high duty cycle could get warm to hot. If you have run your system for a substantial period of time and do not see any heat related issues with the resistors, you could be fine. That said, it would be safer in the long run to change the resistors to 10k ohm.
Thanks,
Tom T
Tom T.
Thanks for the response. My concern was more with damage to the sinking transistors on the Acorn board while sinking that current at 24v. I have some 10k 1/4w but will get some 10K 1/2W also.
Tom
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