Depending on the application, a controller or variable-speed electric-motor drive may need to measure any combination of rotor speed, position, and direction. Absolute encoders are a popular motion control choice with their ability to determine rotor position immediately at power on, while also being able to keep track of position during sudden power losses. With an absolute encoder comes the choice between a variety of communication protocols used to connect to the host system, but which combination of benefits and features are ideal for your design?
SPI (Serial Peripheral Interface), RS-485 (aka TIA/EIA-485), and SSI (Synchronous Serial Interface) are several of the most common options available. When it comes to making a selection, each choice will depend on a variety of factors such as protocol latency, max data rate, connection distance, and noise immunity.
This CUI Insights blog post, “Integrating Absolute Encoders – An Overview of SPI, RS-485, and SSI Protocols” discusses the SPI, RS-485, and SSI communication protocols in further detail, equipping readers with a better understanding of their implementation and benefits.