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EnDat / SII / BiSS Serial Absolute Encoders

This section provides wiring instructions for motors equipped with one of the following types of serial absolute encoders:

• Heidenhain EQN1135, EnDat 2.2, 23-bits/revolution, 12-bit multiple turns counter
• Heidenhain EQI1130, EnDat 2.1, 18-bits/revolution, 12-bit multiple turns counter
• SSI with n-bit position counter (configurable resolution)
• BiSS-B/BiSS-C with n-bit position counter (configurable resolution)

These encoders transmit their position data using different specialized serial bit stream protocols (via a RS-485 pair) rather than A-B incremental quadrature pulses. Unlike other absolute encoders, these devices also require a second RS-485 pair to transmit a data clocking signal from the controller to the encoder. In general, these encoder types do not require a battery backup source to maintain their multiple turns counter.

Due to the additional capabilities needed to process the absolute encoder signal, these encoders may require the "Enhanced Encoders" license. Contact Brooks for the current hardware requirements for interfacing to these types of encoders.

For information on configuring these types of encoder, see the Software Setup section of the Controller Software section of the PreciseFlex Library.

In addition to Table 12-45, review the Installation Information for important recommendations on the use of twisted pair wires and shield grounding.