If you’ve ever worked on a machine that lost its position after a power cut, you know that sinking feeling. You turn everything back on, and suddenly the system doesn’t know where it is. Operators are waiting, production halts, and you’re scrambling to get it back online. Absolute encoders exist to solve that exact problem.
Unlike incremental encoders, absolute position rotary encoders never forget their position. Power goes out? No problem. Power comes back? The system knows exactly where it left off. No homing, no guesswork, no wasted time.
But knowing the encoder itself is reliable is only half the story. That position data still has to reach the controller, and how it does so depends on the communication protocol. Picking the right one makes a huge difference in how smooth and reliable your system feels.
Why Do Communication Protocols Matter?
Think of a communication protocol as a language between the encoder and the controller. The encoder knows the position, the controller knows what to do with it, and the protocol is how they “talk” to each other.
Get the wrong one, and you’ll see lag, jittery motion, or even missed counts. Get it right, and the system just works, every axis, every time.
Protocols matter because they affect:
- How fast does the system respond?
- How smooth is the motion?
- How much wiring do you need?
- How well does the system handle electrical noise?
- How easily can multiple devices work together?
Also read from our previous blogs – Rotary Encoders: Applications, Accuracy, Microcontroller Interfacing and Troubleshooting
Common Protocols in 2026
There isn’t a single “best” protocol. It depends on your system and what it needs to do.
SSI (Synchronous Serial Interface)
SSI is simple, reliable, and still very common. The controller sends a clock signal, and the encoder responds with its position. That’s literally it.
Why engineers still use SSI:
- Easy to wire
- Strong resistance to noise
- Compatible with most PLCs
- Cost-effective
If you have a straightforward axis on a CNC machine or a servo system, SSI usually gets the job done. Sometimes, simple really is better.
CANopen
CANopen is ideal when multiple devices need to talk on the same network. Think robotic arms, AGVs, or packaging lines.
It allows devices to share the same bus and has built-in error checking. That means your robot arms, conveyors, and sensors can all talk without constant intervention.
EtherCAT
When timing is critical, EtherCAT is your friend. Multi-axis CNC machines, robotics, and high-speed production lines rely on it.
It provides:
- Extremely fast updates
- Perfectly synchronized axes
- Real-time deterministic performance
If you’ve ever seen a robot arm move smoothly while multiple axes coordinate perfectly, EtherCAT is probably behind it.
PROFINET and PROFIBUS
Common in larger factories, especially those running Siemens PLCs. PROFINET is an Ethernet-based protocol that offers high-speed communication, scalability, and diagnostics.
Usually, you choose these for compatibility. If the plant already uses Siemens systems, these protocols plug right in.
Industrial Ethernet (EtherNet/IP and others)
Ethernet-based encoders don’t just send positions. They also send device health info and diagnostics.
That means:
- You can monitor remotely
- Predictive maintenance becomes possible
- Integration with smart factory systems is easy
In a connected factory, it’s a way to spot issues before they stop production.
How is resolution defined in absolute encoders?
Resolution is how finely the encoder measures position. Higher resolution = smoother motion, better precision.
- 12-bit = 4,096 positions per rotation
- 16-bit = 65,536 positions
- 18-bit = 262,144 positions
Don’t just grab the highest resolution. Match it to your system. Too little resolution = jerky motion. Too much = unnecessary cost.
Single-Turn vs. Multi-Turn
Absolute encoders come in two flavours:
- Single-turn: Measures position within one rotation. Perfect for machines that don’t rotate continuously.
- Multi-turn: Tracks full rotations and remembers position even after power loss. Perfect for elevators, robotic arms, and rotary tables.
Picking the right one keeps things reliable and saves you time in setup and troubleshooting.
Speed and Direction
Absolute encoders measure position. Speed and direction aren’t measured directly; the controller calculates them from changes in position over time.
- Read position now
- Read it a moment later
- Difference = speed
- Increase or decrease = direction
With high-speed protocols such as EtherCAT or PROFINET, this calculation is precise enough for even the most demanding motion applications.
Power Loss, Why Absolute Encoders Shine
This is where absolute encoders really earn their keep.
When power returns:
- The system knows exactly where it is
- No homing required
- Machines start immediately
Multi-turn encoders often use gears or battery-free electronic tracking to retain position. For plants running 24/7, this saves hours of downtime over a year and prevents unnecessary wear on your equipment.
The Bottom Line
Absolute encoders provide reliable, precise feedback your system can trust. They use protocols such as SSI, CANopen, EtherCAT, PROFINET, and Industrial Ethernet to get that position data to where it needs to go. Their resolution ensures smooth motion, multi-turn models remember position through power loss, and they reduce setup time and downtime.If you want high-quality rotary encoders that just work, every time, without guesswork, buy online at Briter Encoder. Reliable, precise, and ready for the real world.
