Before we dive into specific cables… all DYNAMIXEL servos communicate via UART-based protocols (Protocol 1.0 or 2.0). However, different servos use different physical connectors:

3-Pin → for TTL communication (typically AX, MX, XL series TTL models).

4-Pin → for RS-485 half-duplex communication (typically X, P, XM, XH series).

Your controller/interface should match the communication type (TTL vs RS-485).

DYNAMIXEL Cable Types & When to Use Them

1. TTL / 3-Pin Cables — for TTL-Only Servos

Used primarily on DYNAMIXEL X servos that only support TTL/3-pin UART communication 

Connector: JST 3-pin

Signals: GND, VDD, DATA (half-duplex)

Use when: servo supports TTL logic level directly.

Models Supported: All DYNAMIXEL-X models ending in T.

? Tip: You can find JST connector information available in our e-Manual

2. RS-485 / 4-Pin Cables — for Modern RS-485 Servos

Used for advanced DYNAMIXEL servos that use half-duplex RS-485 communication (X-series, P-series, XM, XH, etc.). They provide a differential pair plus power and ground.

Connector: JST 4-pin

Signals: GND, VDD, DATA+, DATA-

Use when: servo uses RS-485 interface.

Models Supported: All DYNAMIXEL-X Series ending in R, and P-Series Actuators

Interfaces, Adapter Tools, & Older Model DYNAMIXEL

Most PCs and microcontrollers don’t have native DYNAMIXEL ports, so an interface, such as the U2D2, is often required. This is especially important if your controller does not support half-duplex communication, which DYNAMIXEL servos rely on.

When working with older DYNAMIXEL models like the AX or MX series, cable selection becomes even more important. These actuators use different connectors and communication standards than newer models, meaning the cables used for X-series or P-series servos may not be compatible.

For AX and MX series using TTL communication, the following cables are what would be needed for DYNAMIXEL to DYNAMIXEL daisychains, and for connections to older / 3rd parts hardware:

As for the RS-485 Version, you would want the following;

Mixing Old and New Tech

When it comes to DYNAMIXEL, it's certainly possible to mix the AX, MX, X, P, and Y series actuators, assuming they are all running DYNAMIXEL Protocol 2.0. You just need to make sure you set up your daisychains using the correct cables. Convertible cables allow you to connect Molex connectors to JST connectors with no adverse affects. 

TTL Verstion: 

RS-485 Version:

Same goes for pairing old DYNAMIXEL with new controllers. If you're running into isuses, the first thing to check is that you're using the correct cables!

Ultimately, choosing the correct cable for your DYNAMIXEL setup comes down to three key factors: communication type (TTL vs RS-485), connector style, and actuator generation. Whether you’re working with legacy AX and MX models or modern X- and P-series actuators, matching the cable to the servo and interface is essential for reliable communication. When mixing old and new hardware, double-check your daisy-chain layout and connector conversions, many connection issues can trace back to cable mismatches. If something isn’t working as expected, verifying that you’re using the correct cable is always the best place to start.