what is the pulse count for a quadrature encoder with 1000PPR resolution

[Gops]

Hi
I want to know what would be the number fo pulses that an quadrature encoder with 1000 PPR resolution gives out when it rotated once.
In MAX for the 7344 card, I used the interactive 1D to check this. I found out that it gives a pulse count of 4000 for 1 rotation.what is the logic involved.
How do we interpret quadrature encoders.

[Jochen]

1000 PPR means 1000 Periods Per Revolution. A quadrature encoder generates two square signals that are shifted by 90°. They are called phase A and phase B. Thus within each period the quadrature encoder generates one rising edge and one falling edge for both phases. The inputs of the 7344 use X4 logic. That means that they are capable of counting every rising and falling edge. This results in 4000 counts for a 1000 PPR encoder.

For schematics and further information please follow this link:

http://zone.ni.com/devzone/conceptd.nsf/webmain/665470207873076386256B35007957A2?opendocument


Regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH