Online diagnostics Cyclic Redundancy Check tolerance limits of the encoder Warning Encoders with pure serial interfaces do not provide incremental signals for evaluation of encoder function. EnDat 2.2 encoders can therefore cyclically transmit so-called valuation numbers from the encoder. The valuation numbers provide the current state of the encoder and ascertain the encoder’s “functional reserves.” The identical scale for all HEIDENHAIN encoders allows uniform valuation. This makes it easier to plan machine use and servicing. To ensure reliability of data transfer, have been reached or exceeded—such as shaft speed or the limit of light source intensity compensation through voltage regulation—without implying that the measured position values are incorrect. This function makes it possible to issue preventive warnings in order to minimize idle time. a cyclic redundancy check (CRC) is performed through the logical processing of the individual bit values of a data word. This 5-bit long CRC concludes every transmission. The CRC is decoded in the receiver electronics and compared with the data word. This largely eliminates errors caused by disturbances during data transfer. Parameters of the OEM This collective bit is transmitted in the status data of the additional information. It indicates that certain automatic confi guration.

Parameters and Memory Areas

A separate memory area contains the parameters typical for EnDat 2.2: Status of additional information, temperature, acceleration, support of diagnostic and error messages, etc.

Monitoring and Diagnostic Functions

The encoder provides several memory areas for parameters. These can be read from by the subsequent electronics, and some can be written to by the encoder manufacturer, the OEM, or even the end user. Certain memory areas can be write-protected.The parameters, which in most cases are set by the OEM, largely defi ne the function of the encoder and the EnDat interface. When the encoder is exchanged, it is therefore essential that its parameter settings are correct. Attempts to confi gure machines without including OEM data can result in malfunctions. If there is any doubt as to the correct parameter settings, the OEM should be consulted. In this freely defi nable memory area, the OEM can store his information, e.g. the “electronic ID label” of the motor in which the encoder is integrated, indicating the motor model, maximum current rating, etc. Operating parameters Absolute encoderSubsequent electronics This area is available for a datum shift and the confi guration of diagnostics. It can be protected against overwriting. The EnDat interface enables comprehensive monitoring of the encoder without requiring an additional transmission line. The alarms and warnings supported by the respective encoder are saved in the “parameters of the encoder manufacturer” memory area. Error message malfunction of the encoder might result in incorrect position values. The exact cause of the disturbance is saved in the encoder’s “operating status” memory. Interrogation via the “Operating status error sources” additional information is also possible. Here the EnDat interface transmits the error 1 and error 2 error bits (only with EnDat 2.2 commands). These are group signals for all monitored functions and serve for failure monitoring. The two error messages are generated independently from each other. Parameters of the encoder manufacturer information specifi c to the encoder, such as encoder type (linear/angular, singleturn/multiturn, etc.), signal periods, position values per revolution, transmission format of position values, direction of rotation, maximum speed, accuracy dependent on shaft speeds, warnings and alarms, part number and serial number. This information forms the basis for An error message becomes active if a This write-protected memory area contains all write protection cannot be reversed. Operating status This memory area provides detailed alarms or warnings for diagnostic purposes. Here it is also possible to activate write protection for the OEM parameter and operating parameter memory areas, and to inter-rogate their status. Once activated, the
Incremental signals 1 V PP A *) *) *) 1 V PP B *) Absolute position valueOperating parametersOperating statusParameters of the OEMParameters of the encoder manufacturer forEnDat 2.1 EnDat 2.2 EnDat interface Depends on encoder

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