Serial Communication Transmission Error

What does CALL mean?

This minor fault indicates that serial communication has not been established between the drive and the master, or that communication was interrupted. It is often caused by faulty wiring, incorrect termination resistor settings, or programming errors on the master side. If left unresolved, the drive will not be able to receive commands or send status updates, leading to system operational failure.

• Loose, damaged, or broken communication cable (e.g., RS-422/485) between the drive's communication terminals (e.g., S+, S-, SG) and the master controller.
• Incorrect wiring polarity (e.g., A/B, Rx+/Rx-, S+/S-) at the communication terminals, preventing proper signal reception.
• Missing or incorrectly set termination resistors (e.g., internal DIP switch SW1) on the drive or other devices on the communication bus, causing signal reflections.
• Incompatible communication parameters (e.g., baud rate b5-01, data bits b5-02, parity b5-03, stop bits b5-04) between the drive and the master.
• Excessive electrical noise or ground loops on the communication bus corrupting data packets.

Click steps to track your progress.

1. 1

   Inspect the serial communication cable (e.g., shielded twisted pair) for physical damage and ensure secure connections at both the drive's communication terminals (S+, S-, SG) and the master device.

2. 2

   Verify the communication wiring for correct polarity (e.g., S+ to master Rx+/Tx+, S- to master Rx-/Tx-) according to the drive and master controller manuals.

3. 3

   Confirm the proper setting of termination resistors (e.g., internal DIP switch SW1) on the drive and external termination on the master or other bus devices.

4. 4

   Match all communication parameters (e.g., b5-01 Baud Rate, b5-02 Data Format) in the drive's settings with the configuration in the master controller.

5. 5

   Use an oscilloscope to observe signal integrity on the communication bus (e.g., across S+ and S-) to detect noise, signal drops, or improper signal levels.