Interfaces Absolute Position Values

The EnDat interface is a digital, position values from both absolute and—with EnDat 2.2—incremental encoders, as well as reading and updating information stored in the encoder, or of saving new information. Thanks to the bidirectional interface for encoders. It is capable of transmitting InterfaceEnDat serial bidirectional serial transmission method only four signal lines are required. The data are transmitted Data transfer Absolute position values, parameters and additional informationData inputDifferential line receiver according to EIA standard RS 485 for the CLOCK, CLOCK, DATA and DATA signalsData outputDifferential line driver according to EIA standard RS 485 for the DATA and DATA signalsCodePure binary code Position valuesAscending during traverse in direction of arrow (see Dimensions) in synchronism with the clock signal from the subsequent electronics. The type of transmission (position values, parameters, diagnostics, etc.) is selected by mode commands that the subsequent electronics send to the encoder. Clock frequency and cable length clock frequency —depending on the cable length—is variable between Without propagation-delay compensation, the 100 kHz and 2 MHz. Because large cable lengths and highclock frequencies increase the signal run time to the point that they can disturb the unambiguous assignment of data, the delay can be measured in a test run and then compensated. With this propagation-delay compensation in the subsequent electronics, clock frequencies up to Incremental signals » 1 V 8 MHz at cable lengths up to a maximum of 100 m are possible. The maximum clock frequency is mainly determined by the cables and connecting elements used. To ensure proper function at clock frequencies above 2 MHz, use only original ready-made HEIDENHAIN cables.
PP (see Incremental Signals 1 V
PP ) depending on unit Connecting cable Shielded HEIDENHAIN cablePUR [(4 x 0.14 mm
2 2 ) + 4(2 x 0.14 mm
2 2 ) + (4 x 0.5 mm
2 )]PUR [(4 x 0.14 mm ) + (4 x 0.34 mm )]WithWithoutincremental signalsCable length † 150 m ( † 100 m in safety-oriented applications)Propagation time † 10 ns; typ. 6 ns/m
Cable length [m] Clock frequency [kHz]
EnDat 2.1; EnDat 2.2 without propagation-delay compensationEnDat 2.2 with propagation-delay compensation

Input circuitry of the subsequent electronics

Encoder Subsequent electronicsData transfer Incremental signals Dimensioning IC
1 = RS 485 differential line receiver and driverC
3 = 330 pFZ
= 120 âˆ’ Depending on encoder

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