Renishaw RCU10, Installation And User Manual, Page: 33 / 202

2-10 System design
2.4.1 Encoder input frequency

Determine the encoder resolution.

Determine the maximum required axis velocity (see Tables 2.2 to 2.5 to determine
the maximum velocity for different resolutions and encoders).

Calculate the maximum encoder (edge-to-edge) frequency as follows:
Encoder frequency (MHz) = Velocity (m/s)
Encoder resolution (µm)

Ensure that the encoder frequency is less than 20 MHz and less than the RCU10
sample rate setting.
Note: The input sample rate of the RCU should be at least 25% greater than the encoder
output quadrature rate.
2.4.2 Output frequency

Determine the RCU10 output (controller input) resolution.

Calculate the maximum output frequency as follows:
Output frequency (MHz) = Velocity (m/s)
Output resolution (µm)

Ensure that the RCU10 output update rate is at least 5% greater than the output
frequency.

Ensure that the controller sample rate is greater than the RCU10 update rate
setting.
In the case where analogue (Sine/Cos) output signals are being used from the RCU10,
the frequency of the sinusoids can also be calculated as shown above.
Note: The customer’s controller must have an input bandwidth which is at least 25%
greater than the output quadrature rate of the RCU.