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Troubleshooting C207A0 Fieldbus Input Disconnected Fault (PolyScope 5)

Fix the C207A0 Fieldbus Input Disconnected error on your Universal Robots teach pendant. Usually caused by an enabled fieldbus protocol with no device connected, or a lost connection to your welder.

Written by Matt Bush
Updated today

This article is for robots running PolyScope 5.

If your teach pendant is showing a C207A0 Fieldbus Input Disconnected error, this article will help you fix it.

What You'll See

  • C207A0 error code on the teach pendant

  • The message Fieldbus Input Disconnected in the error details

  • The robot stops with a protective stop

  • Your program cannot start or resume

C207A0 Fieldbus Input Disconnected error displayed on the Universal Robots teach pendant

Quick Fix

Tap Enable Robot on the protective stop popup to dismiss the error. Then disable any communication protocols that are enabled but don't have a device connected — this error means a protocol is turned on with nothing responding on the other end.

Step 1. Disable Profinet

  1. On the teach pendant, tap Installation > Fieldbus.

  2. Tap the Profinet tab.

  3. If it shows a yellow dot and the adapter status says "Running," tap Disable.

Profinet tab showing yellow dot and Running status — this needs to be disabled

Profinet tab showing Disabled status — this is correct

Step 2. Check Ethernet/IP

Tap the Ethernet/IP tab, then check the table below for what to do based on your welder.

Your Welder

What to Do

Miller Deltaweld

Miller Invision

ESAB Aristo

Tap Disable if it shows "Running"

OTC Welbee

Do NOT disable. Your Welbee communicates with the robot over this connection. If it shows an error, see Troubleshooting Fieldbus Communication Error with OTC Welbee.

Ethernet/IP tab showing yellow dot and Running status

Ethernet/IP tab showing Disabled status

Step 3. Test

Try running your program again. The C207A0 error should not reappear. If it does, continue to the next section.

If That Didn't Work

Restart the Robot

If the protocols are already showing as disabled, a restart can clear the fault. For step-by-step instructions, see How to Power On, Power Off, or Restart a Robot.

After the robot boots, try running your program again.

Check for a URCap Issue

Some third-party URCaps use the robot's communication channels. If a URCap crashes or stops responding, it can trigger this error.

  1. On the teach pendant, tap Installation > URCaps.

  2. Look for any URCap besides Beacon that shows an error or warning icon.

If the error appeared after installing or updating a URCap, remove that URCap and restart the robot.

Still Need Help?

If none of the above fixed your issue, tap the chat icon in Beacon to reach our support team. It helps if you can share:

  • A photo of the error on the teach pendant

  • Which welder you have (Miller Deltaweld, OTC Welbee, ESAB Aristo, etc.)

  • Your robot's serial number (printed on a label on the robot's base)

  • Whether you recently installed or updated any URCaps

Related Articles
Installation and Setup
How to Update Universal Robot's PolyScope 5 Operating System
Troubleshooting C203A0 Safety Settings Mismatch Fault
Setting the Correct Startup Program for Beacon Welding
Troubleshooting Fieldbus Communication Error with OTC Welbee
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