Nikon-A Encoder Receiver

Overview

Nikon-A absolute encoder receiver implementation on the TI PRU-ICSS interfaces with the Nikon encoders either via point-to-point communication or up to 8 Nikon encoders connected on a bus. Nikon encoders use a proprietary asynchronous serial bi-directional half-duplex communication protocol compliant with the RS-485. The encoder can generate either single- or multi-turn absolute position data and can operate at a baud rate of up to 16 Mhz. Besides position data, the encoder can also send status and diagnostic information well. Reliability is ensured by using a 3-bit CRC by the controller and an 8-bit CRC by the encoder. Another interesting feature of the Nikon-A encoders is the optional battery backup circuit, which can be used in case of power failure. Nikon encoders are widely used in industrial machinery, including industrial robots in automobile production lines and machine tools, and are highly valued as the next-generation standard for sensors that can detect the absolute rotational displacement values of robot arms. 

Salient Features
  • Support for point-to-point and bus communication.
  • Support for baud rates from 2.5 MHz, 4 MHz, 6.67 MHz, 8 MHz, and 16 MHz.
  • Support for up to 40-bit absolute position (single turn + multi turn) data with additional information.
  • Support for position preset, temperature information and alarms.
  • Support for non-volatile (EEPROM) read and write access.
  • Support for identification code read and write process.
  • Support for encoder address setting.
  • Support for individual and multiple transmission mode with encoder addresses ranging between ENC1-ENC8.
  • Support for concurrent multi-channel support on a single PRU (up-to 3 channels with identical number of encoders of same frequency connected to all configured channels).
  • Support for multi-channel with different communication modes and different number of encoders connected accross channels under load share model (each of PRU, RTU-PRU, and TX-PRU from one PRU-ICSSG slice handles all 3 channels).
Testing Features
  • Tested using 17-bit/16-bit, 20-bit/16-bit, 22-bit/16-bit, 24-bit/16-bit, 26-bit/14-bit, and 27-bit/13-bit single/multi-turn Nikon-A encoders respectively.
  • Tested for baud rates 2.5 Mhz, 4 MHz, 6.67 MHz, 8 MHz, and 16 MHz.
  • Tested for all the commands as per the Nikon-A encoder specifications
  • Validated for safety and reliability with CRC checks as specified by the Standard.
  • Tested with 1 encoder connected in a point-to-point communication setup.
  • Tested with up to 3 encoders connected in a bus.
  • Tested for multi-channel communication modes by simultaneously connected encoders to different PRUs in the ICSS.
Available Platforms

TI AM243x, TI AM64x, TI AM263x

For resource requirements & other details