Using Stepper Motor as an Encoder

[JtotheB]

Here is some information on how to take measurements with a quadrature encoder. Hope that helps!

[SK0480]

Hello John

Ok now I've just read this guide on taking measurement using the quadrature encoder, now it says that two output pulses are necessary to indicate the position and direction-I understand that. It also says that i will need some kind of counter; so iam using a NI elvis board,  does it have a built in counter, or will I need to buy a counter chip to take measurment using a quadrature encoder. Also apart from quadrature encoder, is it a good idea to use something simple liek potentiometer to measure the stepper motor position.

I appreciate your help

SK

[JtotheB]

That depends, if you have the original NI Elvis that will depend on the DAQ device that you are connected to. Most of those DAQ devices will have at least one counter on them. If you have the NI Elvis II, the DAQ that is built into the Elvis has 2 counters so you should be all set.

[SK0480]

Hi

Ok another thing, in the encoder measurment tutorial by NI, it says that there are 4 types of encoding--x1, x2, x3, x4.

and for the rotation motion it gives the following formula:

degrees = Edge_Count / xN

this x in the equation- is this just goin to be number like 1 or 2,

Also to use any type of encoding like x1, x2 , x3 or x4...will I need to configure the counter or encoder to use a particular type of encoding..

can you please clarify on that.

THanks

SK

[JtotheB]

That xN will correspond to the type of encoder. So, for example, if you have an x2 encoder with 200 edge counts per rotation, this will be your formula;

degrees = edge_count / xN

-> degrees = 200 / 2

-> degrees = 100

You will do that configuration in Measurement and Automation Explorer.

[SK0480]

Thanks for your reply ok this helps out a lot. and I really appreciate it.

Is there a way I can also measure the velocity and acceleration using this encoder and the NI Elvis board that I have because in the NI website it shows how to get the velocity and acceleration using the Digital input card and FPGA, but would the same procedure apply if Iam using the NI ELVIS II..

Also, I've never played with encoders before I need to know, once I obtain any encoder, how will I need to connect it to the shaft of my motor.

Thanks

SK

[SK0480]

I know that these quadrature encoder come in two types hollow shafts and a solid shaft....I know that If Iam using a solid shaft encoder I will need to use a coupling, but lets say if Iam using a hollow shaft encoder how will I make sure that it fits the shaft of my stepper motor.

Thanks
SK

[RavensFan]

You'll just have to order it that way based on your stepper motor shaft size.

[SK0480]

Iam using an NI elvis II and it has a built in DAQ board, Iam using a quadrature encoder with my motor, I need to know what type of encoder would be best to use with NI Elvis whether I should use -push pull, open collector etc..

[JtotheB]

Push-Pull encoders are recommended.