Modbus Poll Bytes Missing Error Fixed ●

Based on common troubleshooting for Modbus RTU communication, the "bytes missing" or "bytes not received" error in Modbus Poll

5. Silent Interval (Inter-Frame Delay) Misconfiguration

Some slow slaves need more than 3.5 characters of silence. If your master sends the next poll too quickly, the slave might still be processing, leading to a truncated response. modbus poll bytes missing error fixed

• Use a serial sniffer (like Serial Port Monitor or WireShark + modbus plugin) to capture raw hex.
• Check if Byte Count matches actual data bytes received.
• If mismatch → Slave firmware bug. Contact vendor or update firmware.

Setup → Serial Port

Background

Cable Length and Quality: Ensure you are using shielded twisted-pair (STP) cable. If your run is long (over 10m) without proper shielding, EMI from motors or VFDs can corrupt the signal. Use a serial sniffer (like Serial Port Monitor