Cause : RS-485 communications error comes when a communications error occurred during RS-485 communication. An ER5 RS-485 communications fault indicates a problem in the communication between the Fuji FRENIC-VG drive and a connected device using the RS-485 interface.

"er5" fault in Fuji FRENIC-VG drive indicate "RS-485 communications error". This fault means there is a problem with the RS-485 communication link, which is often used for networked communication with other devices such as PLCs, HMIs, or other drives. This fault means the drive is unable to communicate properly over the RS-485 network.

Troubleshooting Steps:

1. Check Wiring and Connections:

   • Inspect all RS-485 cables and connections for signs of damage, loose connections, or incorrect wiring.
   • Ensure that the A(+), B(-), and ground wires are correctly connected according to the RS-485 standard.

2. Verify Network Termination:

   • Make sure that termination resistors (typically 120 ohms) are installed at both ends of the RS-485 communication line. Without proper termination, signal reflections can cause communication errors.
   • If the network is long or complex, ensure that biasing resistors are also properly installed if required by your setup.

3. Check Communication Settings:

   • Verify that the drive's communication settings (baud rate, parity, data bits, stop bits, and communication protocol) match those of all other devices on the network.
   • Ensure that each device on the network has a unique address if using multi-drop configurations.

4. Test for Electrical Interference:

   • Ensure that the RS-485 cables are routed away from high-voltage lines, motors, or other sources of electrical noise.
   • Use shielded cables and ensure that they are properly grounded.

5. Test the RS-485 Port and Devices:

   • If possible, test the RS-485 communication with another known-good device or port to see if the issue is isolated to the drive's RS-485 port.
   • Alternatively, connect the drive to a different RS-485 network or test with a different cable to rule out cable issues.

6. Check Grounding:

   • Ensure that all devices on the RS-485 network share a common ground to avoid potential differences that could disrupt communication.
   • Verify that grounding is done according to best practices for RS-485 networks.