Short answer

ESP32 Modbus RTU gets CRC errors. What is usually wrong?

  • Baud, parity, and stop bits must match the meter exactly. One mismatch looks like random CRC fail.
  • RS-485 needs a transceiver and correct DE/RE timing. Half-duplex collisions corrupt frames.
  • Bias and termination on long buses matter. A lab short cable can hide a field wiring problem.
  • Confirm slave ID and register map against the vendor sheet, not a generic example.

中文

短答

ESP32 Modbus RTU 总报 CRC 错，多半是什么？

  • 波特率、校验、停止位要和表计完全一致。差一项就像随机 CRC。
  • RS-485 要有收发器，DE/RE 时序要对。半双工撞车会毁掉帧。
  • 长线要考虑偏置与终端。台上短线会掩盖现场布线问题。
  • 从站地址和寄存器表按厂家手册核，不要套通用例程。