TIDUF97 September 2024
This absolute encoder reference design communicates with the host controller through the RS485 interface to transmit the angle data. The communication runs at a 4M baud rate UART protocol. The host controller sends different T-format command request and the encoder responds with the corresponding field stipulated by the T-format protocol. Figure 3-14 shows an example communication. For more details on the T-format protocol, refer to TAMAGAWA Encoder Catalog.
The software is configured to respond to the ID3 command, which requires to return all of the encoder data, including command field, status field, single-turn data field, encoder ID, multi-turn field, alarm field, CRC field, total 11 bytes. The field format is listed in Table 3-2. Since the angle is calculated in IQ21 format in MCU, 3 bytes of data field are required to transmit the angle data.
Bit1 | Bit2 | Bit3 | Bit4 | Bit5 | Bit6 | Bit7 | Bit8 | Bit9 | Bit10 | |
---|---|---|---|---|---|---|---|---|---|---|
Content | Start bit, always 0 | The content depends on the specific field. These 8 bits of data are included in the CRC calculation. | Stop bit, always 1 |