What does the motor encode index channel mean for?

[bittware]

Hello experts,
Could you explain how to use index channel of motor digital encoder in normal case? I can't figure out why this extra channel exists.

Thanks in advance.

 

[IanP]

Have a look at the picture below; it explains what the index signal is used for ..
Regards,
IanP

 

[bittware]

Hi IanP,
I don't think without homing process, you can derive absolute position only from index channel feedback.
For counting revolution number, a decoder counter with two channels is enough. No need for index channel.
What do you think?

Best regards,
Bittware

 

[IanP]

I agree with you that in the most cases you won't need this feature..
However, it is usefull if you need absolute orientation in situations when, say power is lost, and after power is restored you try to find reference to something ..
Regards,
IanP