In Danfoss VLT frequency converters, error code 84 (Err 84) indicates a communication issue between the frequency converter and the Local Control Panel (LCP). This means the LCP cannot communicate with the drive, preventing proper control and monitoring.

Here's a breakdown of the error and some troubleshooting steps:

Reasons for Error 84:

• Disconnected LCP: The LCP might be physically disconnected from the drive or the connection cable might be faulty.
• Incorrect LCP Settings: In some cases, if the LCP settings are not configured correctly to communicate with the specific drive model, it can lead to Error 84.
• LCP Malfunction: Less likely, but a malfunction within the LCP itself could prevent communication with the drive.
• Drive Hardware Issue: In rare instances, a hardware problem on the drive's communication interface might be causing the error.

Troubleshooting Steps:

1. Check LCP Connection: Verify that the LCP is properly plugged into the communication port on the drive. Ensure the cable is secure and there are no visible signs of damage.
2. Consult Manuals: Refer to the user manuals for both the Danfoss VLT drive model and the LCP. The manuals should provide specific instructions on the proper connection method and communication settings for your setup.
3. Verify LCP Settings: Double-check the LCP settings to ensure they are configured to match the communication protocol and baud rate required by your specific Danfoss VLT drive model.
4. Try a Different LCP (if possible): If you have another compatible LCP available, try connecting it to the drive. This can help isolate whether the issue lies with the original LCP.

Reset the Drive (if applicable): Some Danfoss VLT models might have a reset function that can clear communication errors. Consult the manual for instructions on how to reset the drive safely (if applicable).