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How to troubleshoot the USB connection for the Arc Roasters (Multi barrel) roast machine

Written by Nikolett Takacs

Updated at February 25th, 2026

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Table of Contents

Issue Solution Step 1: Identifying the Serial port Step 2: Selecting the correct Serial port

Issue

Switching the USB cable to a different port on your computer may cause the operating system to reassign the Serial Port (COM port). This change can prevent Roasting Intelligence from recognizing the machine until the new port is selected in the settings.

When a serial port is reassigned, Roasting Intelligence is unable to locate the previously saved port. This mismatch results in a 'No sources connected' error, as the software is looking for a connection that no longer exists.

Solution

You need to assign the correct Serial port to the barrel in the affected Roasting Intelligence instance:

Step 1: Identifying the Serial port

  1. Log in to Roasting Intelligence.
  2. Navigate to Preferences > Machine > Configuration.
  3. In the Machine section, identify which barrel is selected (e.g., Arc Roaster Barrel 1).
  4. Navigate to the Select the Connector setup section and click theGear icon.
  5. Click on the Serial port dropdown. Take note of the Serial port options that appear, e.g., COM3 and COM5.
  6. Switch to the Machine > Measurements tab. In the dropdown for every measurement, ensure Arc Roasters is selected.
  7. Note to the barrel selected from the Configuration tab > Machine field (e.g., Arc Roaster Barrel 1) and disconnect the USB cable corresponding to the barrel. If you are working on the Arc Roaster Barrel 1, unplug the USB cable for that specific barrel. 
  8. Once unplugged, the missing Serial port identifies your barrel. For example, if COM3 disappears from the list (Step 5), then COM3 is the Serial port for Barrel 1.
  9. Click Save to finalize the changes.
     

Step 2: Selecting the correct Serial port
 

  1. Reconnect the barrel's USB cable to the computer.
  2. Navigate to the Select the Connector setup section and click theGear icon.
  3. Click Update.
  4. Choose the Serial port that corresponds to your barrel.
  5. Click Save to confirm the changes.
  6. Restart Roasting Intelligence. 
    💡Follow these steps again to find the correct serial ports for your other barrels.
 

 If you have further questions, feedback, or concerns, please submit a support ticket directly from support.cropster.com. 

 

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