Vernier Software and Technology
Vernier Software & Technology

Go Direct® Rotary Motion Sensor User Manual

Go Direct® Rotary Motion Sensor

Go Direct Rotary Motion is a bidirectional angle sensor designed to measure rotational or linear position, velocity and acceleration. It is used for a variety of applications, including

  • Determining rotational inertia
  • Investigating angular motion applications of Newton's second law
  • Investigating conservation of angular momentum
  • Verifying Malus's law
  • Studying the motion a physical pendulum
  • Measuring linear position for experiments such as the inverse square law of light

Note: Vernier products are designed for educational use. Our products are not designed nor are they recommended for any industrial, medical, or commercial process such as life support, patient diagnosis, control of a manufacturing process, or industrial testing of any kind.

What's Included

  • Go Direct Rotary Motion
  • Micro USB Cable
  • Thumb screw
  • 3-step pulley and mounting screw
  • O-ring

Compatible Software


The 3-step pulley can be mounted on the rotating shaft in either of two orientations: with the wide side of the pulley near the sensor body, or with the narrow side of the pulley near the sensor body. The easiest way to insert the 3‑step pulley on the Rotary Motion Sensor shaft is hold the shaft to prevent rotation as you turn the pulley to align the key to the slot. The O-ring can be slipped over the outer pulley to increase friction when the pulley is in contact with a surface.

The thumb screw can be threaded into the back of the sensor allowing the Rotary Motion Sensor to be attached to a ring stand.

The sensor also has a set of accessory mounting holes that allow it to connect to existing accessories such as the Polarizer Analyzer (PAK-OEK) and the Rotary Motion Motor Kit (MK-RMV).

Getting Started

Please see the following link for platform-specific connection information:

Bluetooth Connection

USB Connection

  1. Install Graphical Analysis 4 on your computer, Chromebook™, or mobile device. See for software availability.
  2. Charge your sensor for at least 2 hours before first use.
  3. Turn on your sensor by pressing the power button once. The Bluetooth® LED will blink red.
  4. Launch Graphical Analysis 4.
  5. Click or tap Sensor Data Collection.
  6. Click or tap your Go Direct sensor from the list of Discovered Wireless Devices. Your sensor's ID is located near the barcode on the sensor. The Bluetooth LED will blink green when it is successfully connected.
  7. This is a multi-channel sensor. The active channel is listed in the Connected Devices Sensor Channels list. To change channels, select the check box next to the Sensor Channel(s) you would like to activate.
  8. Click or tap Done to enter data‑collection mode.
  1. If using a computer or Chromebook, install Graphical Analysis 4. If using LabQuest 2, make sure LabQuest App is up to date. See for Graphical Analysis 4 availability or to update LabQuest App.
  2. Connect the sensor to the USB port.
  3. Launch Graphical Analysis 4 or turn on LabQuest 2. You are now ready to collect data.
  4. This is a multi-channel sensor. To change the default channel selections, see

Charging the Sensor

Connect the Go Direct Rotary Motion to the included USB Charging Cable and any USB device for two hours.

You can also charge up to eight Go Direct Rotary Motion Sensors using our Go Direct Charge Station, sold separately (order code: GDX-CRG). An LED on each Go Direct Rotary Motion indicates charging status.


Orange LED next to the battery icon is solid while the sensor is charging.

Fully charged

Green LED next to the battery icon is solid when the sensor is fully charged.

Powering the Sensor

Turning on the sensor

Press button once. Red LED indicator next to the Bluetooth icon flashes when the unit is on.

Putting the sensor in sleep mode

Press and hold button for more than three seconds to put into sleep mode. Red LED indicator next to Bluetooth icon stops flashing when sleeping.

Connecting the Sensor

See the following link for up-to-date connection information:

Connecting via Bluetooth

Ready to connect Red LED next to the Bluetooth icon flashes when sensor is awake and ready to connect.
Connected Green LED next to the Bluetooth icon flashes when sensor is connected via Bluetooth.

Connecting via USB

Connected and charging Orange LED next to the battery icon is solid when the sensor is connected to Graphical Analysis via USB and the unit is charging. LED next to Bluetooth icon is off.
Connected, fully charged Green LED next to the battery icon is solid when the sensor is connected to Graphical Analysis via USB and fully charged. LED next to Bluetooth icon is off.
Charging via USB,
connected via Bluetooth
Orange LED next to the battery icon is solid when the sensor is charging. Green LED next to the Bluetooth icon flashes.

Identifying the Sensor

When two or more sensors are connected, the sensors can be identified by tapping or clicking Identify in Sensor Information.

Using the Product

Connect the sensor following the steps in the Getting Started section of the user manual.


Go Direct Rotary Motion has two channels:

  • Angle
  • Angle (×4)


Angle is a default channel that is active when the sensor is connected. Angle provides precision to 1° of rotation.

Angle (×4)

Angle (x4) can be selected to take advantage of the quadrature encoder. This increases the precision to 0.25° of rotation.



1° or 0.25°

Note: High resolution mode is also known as ×4 mode. When active, the sensor has a 0.25 degree resolution and a limited maximum measurable rotational velocity.

Optical encoder

Bidirectional, quadrature encoder, 360 cycle per revolution

Maximum speed

30 rev/s at 1° resolution

7.5 rev/s at 0.25° resolution

3-step pulley

10 mm, 29 mm, and 48 mm groove diameter


300 mA Li-Poly

Battery life
(single full charge)

~24 hours

Battery life (long term)

~500 full charge cycles (several years depending on usage)

Care and Maintenance

Battery Information

The Go Direct Rotary Motion contains a small lithium-ion battery. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-300).

Storage and Maintenance

To store the Go Direct Rotary Motion for extended periods of time, put the device in sleep mode by holding the button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to go.

Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If possible, store the device in an area that is not exposed to temperature extremes.

Water Resistance

The Go Direct Rotary Motion is not water resistant and should never be immersed in water.

If water gets into the device, immediately power the unit down (press and hold the power button for more than three seconds). Disconnect the sensor and charging cable, and remove the battery. Allow the device to dry thoroughly before attempting to use the device again. Do not attempt to dry using an external heat source.

How the Sensor Works

The Go Direct Rotary Motion uses a quadrature optical (incremental type) encoder to measure the amount and direction of rotation. The encoder, which is attached to the rotating sensor shaft, consists of a coded pattern of opaque and transparent sectors. The quadrature encoder produces two pulse output patterns 90° apart in phase. The position of the shaft is determined by counting the pulses. The phase relationship between the output signals determines the direction of rotation.


For troubleshooting and FAQs, see

Repair Information

If you have watched followed the troubleshooting steps and are still having trouble with your Go Direct Rotary Motion, contact Vernier Technical Support at or call 888-837-6437. Support specialists will work with you to determine if the unit needs to be sent in for repair. At that time, a Return Merchandise Authorization (RMA) number will be issued and instructions will be communicated on how to return the unit for repair.



Vernier warrants this product to be free from defects in materials and workmanship for a period of five years from the date of shipment to the customer. This warranty does not cover damage to the product caused by abuse or improper use. This warranty covers educational institutions only.


When disposing of this electronic product, do not treat it as household waste. Its disposal is subject to regulations that vary by country and region. This item should be given to an applicable collection point for the recycling of electrical and electronic equipment. By ensuring that this product is disposed of correctly, you help prevent potential negative consequences on human health or on the environment. The recycling of materials will help to conserve natural resources. For more detailed information about recycling this product, contact your local city office or your disposal service.

Battery recycling information is available at

Do not puncture or expose the battery to excessive heat or flame.

The symbol, shown here, indicates that this product must not be disposed of in a standard waste container.

Contact Support

Fill out our online support form or call us toll-free at 1-888-837-6437.

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