Enhanced communication reliability and performance for motor control encoder applications
04 March 2019
Rotary encoders are widely used in industrial automation systems. While the primary purpose of the encoder is angular position and speed measurement, additional features, such as system diagnostics and parameter configuration, are common as well.
Figure 1 shows a motor control signal chain using RS-485 transceivers and microprocessor to interface between the absolute encoder (ABS encoder) slave and industrial servo drive master for closed-loop control of an ac motor.
The RS-485 communication link between the servo drive and ABS encoder typically requires high data rates up to 16MHz and low propagation delay timing specifications. The RS-485 cabling typically extends to a maximum of 50m, but in some cases can be as long as 150m. Motor control encoder applications are challenging environments for data communications, because electrical noise and long cable lengths affect the integrity of RS-485 signaling. This article focuses on key benefits for motor control applications using Analog Devices 50Mbps (25MHz) ADM3065E RS-485 transceiver and the ADSP-CM40x mixed-signal control processor.
Read the full article in the March issue of DPA
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