How I can get my encoder position from RPM to mm/sec?

[Uli21]

Hi,

I get the velocity in RPM and I need a mm/sec. How I can change it and how I can prove if it is correct? Who has got some ideas?

I am using "read velocity in RPM" and also "read velocity", give me different results. Have no idea how can I deal with it.

Using UMI 7764 and PCI 7342 and a linear encoder.  

Thanx.

Message Edited by Uli21 on 11-17-2009 12:28 PM

[elset191]

Knowing nothing about your setup I come up with

RPM*circumference/60

EDIT: You said linear.  We use rotary.  I assume you want linear mm

Message Edited by elset191 on 11-17-2009 12:43 PM

[Uli21]

Hi,

 thanks. I think I am using the wrong vi for this. Because a linear encoder is not working with rotary or anything. So there is no real circumstences.

I have to find another way I think.

Do you have an idea?

[Hummer1]

Hi,

Could you tell us a little about your physical set up?  (what model linear encoder for example)

Do you have a rotary encoder attached to a shaft that has a pully on the end?  If so, then the first post is correct for knowing how fast the line will come off the pully... RPM(Revolution/min)*Circumference(mm/Revolution)/60(seconds/min)=mm/sec  which is how fast the outside of the pully is traveling in mm/second.

Hope that helps.

Hummer1

[johnsold]

If you are using a linear encoder, it should have a specification for the number of pulses per unit length (pulses per mm or pulses per meter).  Rotary encoders are specified in pulses per revolution.  With your specification and some math like Hummer1 showed, you should be able to calculate your speed.

Lynn 

[Uli21]

Hi,

I am using a  linear encoder (SGH PC) for stepper motor. just one direction, encoder didn't move rotary.

The manual says one period is 12.7  mm and for different resolutions I have different counts/inch. 

Have to found out how many counts are how many mm, because I try to divide the counts by 12.7 but it isn't correct. Do someone have an idea? 

[Hummer1]

Sorry, I'm confused. 

You are controlling a stepper motor.

The encoder says that one period is 12.7 mm.  (is a period one revolution?)

If the stepper motor goes one revolution and produces 12.7 mm of motion, then how many steps does it take to get the motor to go one revolution?  Or is it a linear stepper actuator...

Motion/Step = (Steps per revolutin)/12.7 (mm/revolution)

could you send a sketch or something...?

Just trying to help.

[Hummer1]

Also counts per inch must be converted to counts per mm

Counts per mm = counts per inch * mm/inch

from the web

		1 millimeter / inch = 0.0393700787
		More about calculator.

[Hummer1]

OOPS

Counts/mm = Counts/inch * inch/mm

		1 inch / millimeter = 25.4
		More about calculator.