NI 9505 encoder resolution?

[bogdan_ETH]

Hello,

I have the following hardware setup:

- compactRIO 9074 controller with one NI 9505 (DC Brushed Servo Drive) and NI 9263 (Analog Outputs).

- Maxon Motor RE 40 (no load speed ~ 7500rpm)

- Gurley Encoder R137 (180000 cycles/rev = 720000 counts/rev after quadrature) --> the signal from the encoder is connected to the NI 9505 motor drive on the specific slot for encoder.

The problem that I am facing is that the NI 9505 module cannot detect velocities higher than approx. 1130rpm. I tried with a much smaller resolution encoder (2000 counts/rev) and it works just fine. It seems to me that somehow the resolution the NI 9505 module is reading in the counts is not large enough or something similar. Has anyone experienced a similar problem? What are the exact characteristics I should look for in the datasheets to try to match the encoder resolution with the card resolution?

Thank you,

Bogdan

[JoGrMu · Accepted solution]

Hello Bogdan,

please have a look into the "NI 9505 Operating Instructions and Specifications" (http://digital.ni.com/manuals.nsf/websearch/8F6DCAB89D6B9BAD862576850075EA18). On page 29 you will find in "Encoder Input Characteristics" the value for "Maximum quadrature frequency". That frequency is for the NI 9505 f=5MHz.

Regards,

Johannes Graeper

Applications Engineer

National Instruments

[bogdan_ETH]

Thank you very much for the response Johannes.Also it seems that the output frequency of my encoder is lower than what NI 9505 can take in (=5MHz).

Best regards,

Bogdan