RE: [CAD_CAM_EDM_DRO] encoder type?

Hi Jeff,

Here is a real basic run down.

TTL is a signal line that has an off state of zero volts and an on state of
+5 volts. The signals actually have a range of 0 to 0.7 volts low and 2 to 5
volts high. Anything between 0.7 and 2 volts is unstable and can be
misinterpreted by logic.

A differential encoder has two wires per channel, A+ and A-, B+ and B-. They
are designed this way to help eliminate noise on the signal wires. In a true
differential application a differential receiver is connected to the two
outputs per channel and converts them back to TTL levels for the logic to
interpret. In actuality you can drive TTL inputs with a differential output
by tying the negative signal to ground and using the positive signal for
positive logic or tying the positive signal to ground and using the negative
signal for negative logic.

Quadrature is simply the coding scheme used by encoders to indicate
direction of motion. When traveling one direction the rising edge of channel
A will lead the rising edge of Channel B by 90 degrees. In going the other
direction the two reverse so B leads A by 90 degrees.

Most encoders are quadrature whether they are TTL or differential. There is
however other encoder coding schemes.

Hope this clears things up for you.


Best,

Ed Gilbert

Gilbert Engineered Systems
632 Warrenton-Embro Road
Macon, NC 27551
252-257-0539

> -----Original Message-----
> From: jeff35m_73068 [mailto:jeff35m_73068@...]
> Sent: Thursday, March 04, 2004 12:04 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] encoder type?
>
> could someone explain to me the difference between; ttl,
> differential, and quadrature encoders.
>
>
>
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