Encoder Speed

[54Oval]

I'm planning a major upgrade to my homebuilt CNC Machine. My current thought is to use Gecko's GRex to send step direction signals to Rutex R2010's. As the Grex can generat step/dir signals very quickly I want to use the largest line count encoder that I can. The Rutex website lists Encoder speed of 200,000 steps.

Assumeing this meens 200,000 steps / second...
200,000 steps/sec * 60 sec/min = 12,000,000 steps / min

To achieve say 3000 rpm...
12,000,000 steps / min * 1/3000 min/Rotation = 4000 steps / rotation

If 4 steps = 1 line count than would a 1000 line count encoder be the maximum that I could install without lowering the top speed?

-Dan

Also does anyone have experience with the Keiling KL34-170-90 Servo Motors?
http://www.kelinginc.net/ServoMotor.html

[rutexus]

I'm planning a major upgrade to my homebuilt CNC Machine. My current thought is to use Gecko's GRex to send step direction signals to Rutex R2010's. As the Grex can generat step/dir signals very quickly I want to use the largest line count encoder that I can. The Rutex website lists Encoder speed of 200,000 steps.

Assumeing this meens 200,000 steps / second...
200,000 steps/sec * 60 sec/min = 12,000,000 steps / min

To achieve say 3000 rpm...
12,000,000 steps / min * 1/3000 min/Rotation = 4000 steps / rotation

If 4 steps = 1 line count than would a 1000 line count encoder be the maximum that I could install without lowering the top speed?

-Dan

Your figures look ok to me for that speed.

Also does anyone have experience with the Keiling KL34-170-90 Servo Motors?
http://www.kelinginc.net/ServoMotor.html

The KL34-150-90 will run ok on the R2010 drives, but I believe the -170 is a little too large for that drive. Unfortuanately, I'm temporarily out of stock on the R2020 drive that it would need. I am hoping to have some new ones that I can sell in a couple of months. The Australian office is working on some improvements to the drive.

Tom Eldredge
Rutex LLC

[Mariss Freimanis]

The ultimate limit is the encoder output frequency. US Digital lists 100kHz for their E5S series encoders. This makes 400kHz as the maximum step pulse frequency if a "times-4" quadrature encoder is used.

Mariss

[54Oval]

Thanks for your feedback. CNCZone is amazing. Where else could you ask a question about a drive and controller from different manufacturers and actually get responses from both companies overnight.

Perhaps this is a naïve question, but I have to ask. Does the encoder connect to the drive the controller or both? I was asuming that it would be required on the drive.

-Dan

[mecheng10]

Dan,

For sure the encoder needs to be connected to the drive. I am not sure about your specific controller, but I have never seen one that accepts encoder signals as control loop feedback, so I would say in a majority of cases you would not connect your encoders back to the controller.

-Brian

[54Oval]

Thanks Brian,
I couldn't imagine how the drive would know how far a step was without the encoder connected, but I've never used anything but a breakout board before. I am still a little confused as to exactly how large of an encoder I can use. Rutex's website lists the Encoder speed of 200,000 steps, but Mariss indicated that the limit was the US digital encoder's 100kHz which would yield 400kHz step pulse frequency. So I don't know if the 200K from Rutex is encoder pulse meaning 800kHz steps, or actual Steps...

-Dan

BTW, the G-Rex does have Encoder inputs for each axis and does keep track of lead, lag. As far as I know they give your software a view of what the axis is doing. This is used for verifying stepper movements, or to return to a specific location after disabling the drives and freewheeling the axis's. The Rutex card accepts differential encoder signals and outputs both raw and decoded signals

[Kelinginc]

We tested KL34-170-90 Servo Motors using R2010 drives. It worked very good. John