EnDat 2.2

This chapter is only valid for SMM R_03-00-003.

General information

  • To support EnDat 2.2, the servo drive must be fitted with X23 connector (connector option F3 – refer to (➜ # 1, Part Number Scheme) and (➜ # 1, Connector pinout)
  • AKD2G with Functional Safety Option 3 with F3 Option (X23 connector) supports all safe EnDat 2.2 encoders, linear and rotary, SIL2 and SIL3, except for encoder models with more than 12 multiturn bits

Initial safety setup

All AKD2G support only one safe EnDat 2.2 encoder per servo drive at a time through the X23 connector. You don't need to specify a particular EnDat 2.2 encoder model.

 

Choose between SIL2 and SIL3.

 

To achieve SIL3 with an EnDat 2.2 encoder, specify a maximum acceleration for its step monitoring. For a rotary encoder the specified value is shown in rad/s2 and for a linear one the value is shown in m/s2.

 

The resulting diagnostic coverage must be ≥99%. The diagnostic coverage is calculated as follows:

Expectation_Interval = (3/2) * alpha_max * (385 [µs])2

Diagnostic_Coverage = 100% * (Possible_Safe_Positions - 2*Expectation_Interval) / Possible_Safe_Positions

Rotary Encoders

Due to the parameter range of the permissible acceleration parameter, the diagnostic coverage for SIL3 is always met for rotary encoders. Refer to the encoder datasheet of the manufacturer to get the permissible acceleration.

Linear Encoders

For linear encoders the diagnostic coverage depends on the Measuring Length (ML) specified in the encoder datasheet. This is used as the `Possible_Safe_Positions` in the calculation.

Example for a linear encoder with a permissible acceleration of "alpha_max = 100 [m/s2]" and a Measuring Length (ML) of "Possible_Safe_Positions = 2,040 [mm]":

Expectation_Interval = (3/2) * 100 [m/s2] * (385 * 10-6 [s])2 = 22,234 [µm]

DC = 100% * (2,040 * 10-3 [m] - 2 * Expectation_Interval) / (2,040 * 10-3 [m]) = 99.99%

Refer to the encoder datasheet of the manufacturer for the permissible acceleration.